Monday, 15 September 2025

Vintage and Veteran Car dynamo power management

 Changed; 13/11/2025 - 14/10/2025

DRAFT

I discuss the development of cars from the period of time when they started to become a useful tool, giving people leisure travel rather than just toys of the rich.  Cars remain toys with the vroom-vroom noise and the gear changing to a badly matching internal combustion engine being their most attractive feature.  The noisy supercharged 1920s Bentley is preferred over the faster non-supercharged Bentley classic cars, they are heavy cars that the owner needs to manhandle rather than drive.  All this time, the bicycle was the better vehicle, public transport and walking were good common options.  My 1946 Lenton Sports bicycle was made when bicycles were refined to their best.  This blog discusses earlier car electrical systems and ways to optimise a veteran or vintage car that you wish to continue running using the original dynamo.  I have also included some other historical technical details on cars and bicycles. 

By 1890, bicycles and electric vehicles were quite good, and the horses, which suffered dreadfully at the hands of humans, as told in the story Black Beauty, started to be retired from human exploitation.

I developed three draft circuits and kept some of my earlier field-winding drive circuits, a simple regulator and cut-out circuit in AL-0060-03.  They are for 6V electrical systems, so you need to double the voltages in many cases for 12V electrics.  AL-0060-02 will start generating power from the dynamo (< 400 mV), then use all of that power to power the field windings to their maximum of 6 or 7V by boosting the dynamo output voltage to 7V.  Any surplus can then run the car's electrical systems.  This will provide some power at a lower 600 RPM, where it would have cut out.  At rated dynamo power 1,200 RPM, the system will produce the same power as the original system, but at both lower and higher RPM, the buck-boost system can produce more power than the original car electrics would have; therefore, the dynamo will charge the battery at a higher rate, if required to, when the car is moving faster as well as run all electrical systems of the car.  The unit has a switch option for a car with a magneto ignition.  When none of the electrical systems are in use, recover a deeply discharged battery with a lower current at double battery voltage, very slowly. 

I also explain some of the earlier electrical systems used prior to the battery, generator, and spark ignition systems we have now.  But please advise me by commenting below with other details. 

   
The first car is a 1897 Vallée Vis-à-Vis, which is the earliest example I've discovered of a car with magneto ignition, so the operator did not need to carry a dry or charged-up battery with him, other than for battery mode ignition for starting, which this car might have. 

The second video above is a Swallow (later Jaguar cars) body placed on an Austin 7 rolling chassis.  Holden Australia produced a body for the same Austin 7 rolling chassis.  Dixi USA made Austin 7s from kits, BMW purchased Dixi, and the Austin 7 kit was BMW's first car, which they converted and made with metric parts. 

Both cars' engines can kick back and injure the operator severely or damage the car if the timing is not set to retarded before starting the car.  From about 1930, cars incorporated centrifugal and vacuum timing advance so kick-back should not inadvertently occur but placing your thumb on the handle so it faces the same way as your fingers is still important in case kick-back happens is a good strategy. 

At this time, many car makers made rolling chassis, and carriage makers made the car bodies.  For example, at first, Rolls-Royce just made the rolling chassis; late in the car's life, the saloon car body was often replaced with, say, a fire engine body and equipment.  But whether it was Britain's best car at times, Rover at least shared that claim and probably was Queen Elizabeth II's preferred model.  Early Rolls-Royce car manufacture allowed two weeks for making and setting the rear differential gear; after that, the gears continued to get smoother over the life of the car.  Car and bicycle gears, of course, continue to get smoother during their lifetime.

Rover made some of the first safety bicycles and used the very efficient Lloyd's roller shaft drive on some of their later bicycles.  There are conflicting claims for the invention of the first safety bicycle; it could have been made in the UK or France.  Similarly, with lighting, many people were involved in the development of incandescent lighting.  The horn, bell and lighting were important for bicycles and motor vehicles, and many people were involved in improving the lighting since the 18th century incandescent lighting Incandescent light bulb - Wikipedia.  Swann's carbon filament light bulb was succeeded by the Tungsten filament lamp.  A major development was the chain drive, but there were lots of significant developments around the end of the 19th century. 

All Austin 7s had a dynamo, battery, lights and starter motor, plus a crank handle in case you need it.  But the earlier 1920s Austin 7s used magneto ignition, and the car starts well enough on magneto.  Magneto ignition has a reputation for poor ignition power at low RPM; therefore, cars using it solely suffer from poor starting.  On the other hand, you can start a small engine car with a flat battery on the starting handle.  Later, Austin 7s used the battery, dynamo, with the resistor, contacts, and capacitor Kettering ignition system.   This blog mostly covers Austin, but I mention Morris and Riley, because I also have some vintage books for 1930 to 1940 models of these cars and also Villiers motorbike engines, which used metal or a selenium rectifier (which might be one of the earliest uses of a semiconductor rectifier).  I also found information on early Ford cars on the web. 

 
The first practical electric motors and generators were developed between 1832 and the 1880s.  Two principles were demonstrated by Benjamin Franklin's electrostatic motor in 1748 and Michael Faraday's electromagnetic motor in 1821.  Practical electrostatic motors are being developed and used now; they are low-speed, high-torque, higher efficiency, lower material cost, but are 
lower density than a conventional electromagnetic motor. 

The disadvantage of the automotive dynamo electrical systems is that the battery is not charged at an optimum rate, but varies between being overcharged and having to run the car's electrical systems when idling.  Later in this blog, I discuss the use of automotive LED lighting to conserve the power used, increase the intensity of the lighting and thereby reduce the workload on the battery. 

Raleigh bicycles, the Austin 7, and Mini cars are all classless icons of British manufacturing in their time.  The Austin cars were technically ahead of many other makers. 
 

The mechanical regulator

It's like a relay, which opens a contact to switch the field winding off, although actually it is switched to a low current because of the snubber resistor across the contact.  This snubber resistor reduces the back-EMF (voltage) across the regulator contact, thereby minimising spark erosion of that contact.  The field magnetism and, therefore, the dynamo output, reduce slowly, more slowly with a semiconductor regulator which has a diode for snubbing, plus the iron will be magnetised a little

Therefore, the voltage control is slow, so the dynamo power output would be in excess or lacking periodically.  The battery has to work, absorbing these fluctuations in supply, thereby stabilising the electrical system of the car. 

The contact hovers just opening, sparking slightly and continually, but contact erosion and electrical interference are more modest, consequently.  Electrical interference needs to be minimised, but it won't be possible to eliminate it.  Fitting snubber, resistor and capacitor or capacitor units, and resistive high-tension cables helps.  

The two current sense windings cause the output voltage to increase when the battery charge rate is high to compensate for cable and battery resistance.  The output voltage increases more when the car is using a lot of power, which is faster charging, a less bad compromise than not charging faster and the battery being drained.  These dynamo and regulator systems regulate to 8V or 16V, whereas mass-produced alternators are only made for 12V or 24V systems, which regulate to a lower but more constant 14V or 28V, but do so all the time the engine is running, except after vehicle starting, when neither system can meet the battery's demand. 
 
I do not recall the regulator buzzing on my 1960s Mini or my Anglia but continually making small sparks, but I have read that some regulators do buzz. 

Car wiring diagrams (left above) are difficult to follow.  I have expanded a section so you can see how the dynamo, battery, regulator and cut-out work.  My father redrew parts of these diagrams using coloured pencils; these diagrams have details about circuits and fuses that do not seem to be in published documentation.  This 1936-39 diagram is more like a picture with smooth curves rather than a modern orthogonal diagram.  Mechanical detail drawings for servicing are better and are very good.  

The basic Austin 7 never got the regulator that the Big 7 and other Austin cars had, and manufacturing ceased of that model in 1939.  Manufacturers started including a regulator from 1934, which meant owners could add accessories, but the electrics were still not powerful enough to comfortably run a car radio at the time.  Riley made very desirable cars, but they had not introduced the regulator by 1940.  Ford UK introduced the regulator in 1939, but the earlier cars had the cut-out with the third brush, but not the different dynamo power settings coupled with the light switch, unlike Austin, Morris, Riley and other makes had.

Riley Manual, Instruction and Maintenance.  The diagrams have more black boxes and look nice, but are not so clear.  The book was published in 1952, but it includes pictures of cars as early as 1926, but not such early electrical diagrams.  The electrical section of many car maintenance books is generally the poorer chapter. 

Riley's top right circuit is an earlier magneto ignition before 1932; the other three circuits show the later coil ignition.  The last two circuits show two rather than three wires from the dynamo; therefore, two or three current settings are possible on the earlier cars, so the field current presumably is changed by introducing series resistors in the field circuit in the later cars.  F1 field wire to the selector switch in the later circuits.  No regulator is included in the change list.  All of these Riley cars are negative chassis, 12V, and they never switched to positive chassis, unlike other makers. 


The mechanical cut-out was invented in 1915, web AI tells me.

The dynamo became available in 1832; public mains electricity was first demonstrated in 1864 in the UK, the web tells me, and public corporations started supplying DC electricity from 1879.  The lead-acid battery became available in 1859.  Ignition systems moved to electrical with a battery and a trembler coil, which works like a buzzer, generating a continuous spark for running or just starting.  A French car that used the magneto in 1897, generating a single spark per combustion cycle.  1907 Delage Type F, the car had a starter motor as original equipment.  In 1911, Cadillac developed and fitted the Kettering ignition system.  The cut-out made automotive battery charging systems possible in 1915.  From 1930, the selenium rectifier was used on Villiers motorbike engines for battery charging, the battery for the parking lights and used in battery chargers.  In 1920, starter motor, dynamo and batteries had become common in cars, and the internal combustion engine started to overtake other forms of motive power, but the bicycle was established, straightforward, and a supreme people's vehicle.  It was possible to park your car outside the shop you were visiting, and places visited were different until 1970, when that romantic era for the car came to an end.

I don't know how ignition adjustment was achieved in trembler coil ignition.  Perhaps, by moving the distributor so that the continuous spark does not go to a spark plug, but to somewhere else or is the trembler coil turned off and on during the cycle by another means?  Please comment below if you can tell me? 

Steam cars were very quiet; some were modest speed, others were very fast, but like petrol cars, they needed a lot of maintenance, although the starting was safer than hand cranking an ICE.


 
The very wealthy's most desirable car might be Howard Hughes' 1925 Doble steam car, which uses a steam generator, but unlike the flash boiler always contains a little water, and similarly only boils enough water to use imminently, unlike a kettle that boils a lot of water.  The difference is that it makes super-heated steam and runs at higher temperatures and pressures, more efficiently than the earlier flash boiler type car.  Nearly turn on and go, continues to build up pressure whilst approaching its top speed silently of 133MPH and out-accelerating most cars of its time.  But this was the last of the steam cars; noise and gear changing, which the steam car had neither of, were more popular. 

Whites, similarly, used super-heated steam, a steam generator and had a better condenser, so they used less water, and were an earlier and much more successful maker of probably better steam cars. 

Steam cars, Jay explains, could be damaged by steam hammering due to water in the steam circuits.   But steam cars that required hours to boil a lot of water had mostly ceased to be made by 1890.  But I suspect scalded by steam or a hot part of an ICE was less likely or such a severe issue as starting handle kickback of an ICE?  Similarly, people became wary of being run over by a car, and the fatalities dropped due to crashes and rose due to air quality as more cars were made. 


Electric cars were the first powered vehicles to be turn on and go. 

Like most technology at the time, it would be very expensive. 

  
Early cars required a lot of work getting ready to go, then cleaning up, and oiling after using a motor vehicle.  Steam vehicles were better, being much safer to start, and after 1890, when out for a ride, could go after 90 seconds or straight away if the pilot was lit. An electric vehicle has always been fairly straightforward: unplug and go.  Bicycles were at their best between 1930 and 1960. 

Victorian electric cars, the Volks Electric Railway, Brighton, England, have been running since 1883.  I do not have a picture of the rail, but the picture shows where the rail runs in Brighton. 

Milk floats and forklift electric vehicles like this one, which I found on the web, were everywhere when I was a boy in the 1960s and 70s. 

Regenerative braking is simple with a shunt-wound motor; the speed is set by the ratio of the armature voltage and the field voltage(current).  If the field current is increased, the motor slows, thereby applying braking that causes power to be generated.  If there is also a series winding to boost the torque when going up hill, it will need to be bypassed in the over-run condition, or it will reduce the regenerative braking.  There are two types of compound brush motor, one in which the series winding improves the torque under increased load and the anti-series type, which improves the speed regulation and, as a generator, would increase the braking and power generation even more on a steeper downhill run, which is unlikely to be comfortable. 

Of all the types of vehicles above, the electric milk floats were very well used, and peak production was in 1970.  Electric vehicles and bicycles were the first to be usable by anyone, though they did need to know how to connect and manage the battery charger, and oil them. 


The cut-out and current selector switch

Earlier cars, AL-0055-01Bdid not have a voltage regulator, but one, two or three current settings, high, medium, and low switch and the cut-out relay.  The cut-out is a rough approximation to the diode rectifiers used in a modern alternator.  Circuit diagram created using OrCAD Capture 17, limited trial version.  The generator starts because of the little remnant magnetism in the iron of the field electromagnets.  The dynamo also had the third brush adjustment of the power produced.

The three-brush dynamo with a simple cut-out only system.  A third brush was used to trim the charge rate and was set differently between summer and winter. 
  • The system is not accurate, and it has a lot of positive feedback, so when the dynamo voltage rises, the field winding voltage rises, and the dynamo would generate even more power when the electrical systems need less power.  The battery plays an important part in stabilising the voltage, preventing the voltage from rising.
    • The dynamo iron may be sized so that the field winding saturates at, say, 6V, thereby limiting the dynamo's maximum output current, but the voltage can still increase as the engine speed increases.  The current limiting I described is true of all dynamos and alternators; it is part of their magnetic design. 
    • The field winding fuse protects against voltage from running away at the lower current setting.  In this case, a 1.5A fuse is probably about right, not the higher values I have found recommended on the internet. 
    • I have guessed the switch connection between D, F1 and F2.  By comparison, Ford did not include a dynamo power setting switch prior to introducing the regulator, but the third brush was also used to change the dynamo power output for summer and winter use.  Probably the best strategy is to always run an earlier Ford Model Y car with the headlights on, using the winter setting except when you need to fast charge the battery after starting the car. 
    • Voltage runaway could occur if the battery has become high impedance and so it is unable to regulate the voltage very well.  This occurs if the battery is worn out or the acid level has been allowed to drop too much.  But I have also found that if the acid level drops, and has been topped up with water, the battery's impedance is low and its voltage is very low, until it is charged up, which the car dynamo would struggle slowly to do because the field windings would hardly be driven with any power, consequently. 
  • Some control boxes have a third relay for current limiting; I have not seen one of those, and many car makers never included a third current regulator coil.  In any case, lead-acid batteries are best charged with a constant voltage, which is increased slightly when the charge rate is high.  That is what the current compensation windings on the voltage relay do. 
    Austin Cars - guessing the switch's
    internal connection.  There are two
    or three current rate settings. 
  • Austin 7's later wiring diagram differs in the power setting for the side lights. 
    • When lights and fast charging are required, the side lights are evidently designed to be used instead of the headlights.  Otherwise, the headlights should be used. 
    • Side lights are very dim and best only used when parked, as required on a fast road.  That is, it is a bad but necessary compromise to drive on sidelights when the higher rate of charge is required.
    • Earlier Austin 7s, other cars and makes, side lights use the medium current setting.  A wire shown dotted is connected between the F1 terminals.  So, there was no high charge rate when the lighting was switched on, and there was no power to spare anyway. 
  • The driver monitors the ammeter and reduces the charge rate when the battery has recovered from starting the car and the charge rate has died back.  The electrical system has no protection if the charge rate is left set high for too long.
    • The driver needs to move the charge rate switch according to the ammeter, and what inspecting the battery electrolyte tells him.  Use a hydrometer, or if the battery needs topping up more often than once every two weeks, or if bubbles form after a long drive, you need to reduce the charging rate.  But if there were just one bubble in each cell after a long drive, the charging is about right.  [if I remember correctly].  It is necessary to adjust the third brush on the dynamo periodically. 
    • The manual says the ammeter reading should come down to +2A to +4A trickle charge, which is a necessary high rate to compensate for when the electrics are running on battery whilst idling.  Therefore, a car, as I said, was only suitable for a hands-on person. 
  • The Austin 7 electrics total was up to 70W; the dynamo was rated at 6V, 11A, but most other models and makes were rated higher than this, and earlier Austin 7s may have had a lower dynamo rating.  The battery was 50AH, probably 300A maximum?  Austin car club say 300-400A was the initial current of the starter.  This would be the short-circuit current of the battery, cables, and motor before the crank has movement.  100A, used to be said for starting, it could not be higher for maximum power transfer, allowing for battery wear, when cranking.  The spark voltage was about 25,000V, but the Austin Manual says 6,000V, no doubt, when the spark plug was connected. 
  

When I was very young, from 1959 to 1963, I was taken on holiday 250 miles a few times, to Devon and Cornwall, from Kent in an about 1935 Austin 7 and each of two Morris 8s.  Mum complained that she had to keep kicking in the foot well of the passenger side to keep the electric fuel pump running on one of the Morris 8s.  Later, we went further, but in bigger cars.  My father also drove his small Ford Anglia to Paris, a similar distance, with his mates.  Most cars had worm and wheel, or worm and pin steering box; some had rack and pinion steering and less well-developed damping and suspension, though sport bicycles, of the time, had much better active damping due to their apparent tuning with the cyclist, regardless of his weight, but sensitivity to placement of weight on a cycle rack.  Otherwise, the cars have a tendency to wander about on the road like the Austin 7 in this video.  The ignition timing adjustment placed on the steering wheel was replaced by about 1930 with the centrifugal advance and vacuum advance mechanisms within the distributor.  The second video features a much smarter car, a Riley, but it could be an MG or one of the less basic Morris or Austin cars. 

Most parts for cars were made by Lucas Industries - Wikipedia.  Ford used their own branding, though they would have bought in parts made by other suppliers, like all makers do. 

 
The mechanical cut-out does not turn on or off precisely, so when the engine slows down, the dynamo will start drawing current from the battery, but when the current drawn increases enough, the cut-out will disconnect.  By comparison, an alternator provides power even when the engine is idling and the rectifier diodes switch precisely.  It is also likely that the early 4-pole type dynamo produced power even when the engine was idling, so that the inefficient cut-out only needed to operate when the engine was running and open when it is stopped. 

The regulator and cut-out;

The regulator, a higher-rated dynamo with forced air cooling and hydraulic brakes, started to be fitted from about 1935.  These reduce the frequency of maintenance and improve those systems.  Battery life increased from 1-2 years to 5-7 years (web search).  In modern cars, the battery lasts as long as the car and requires no maintenance, which can be over 20 years.  The earliest regulator was used on a car in about 1929, and hydraulic brakes started to be introduced in 1921.  In about 1935, both Austin and Morris switched the battery polarity to positive earth; this probably reduced cathodic corrosion slightly of the car's chassis.  Riley never introduced hydraulic brakes, switched the battery to positive chassis or introduced the regulator until after 1940; eventually, Riley became a badge used on some BMC car models. 

AL-0055-02B veteran car regulator and cut-out, wiring diagram.  The three-phase alternator, electronic regulator and rectifiers replaced the dynamo, the electromagnetic regulator and the cut-out by 1970.  Many more circuits were fused, and relays were added for the high-power headlight circuits.  The component and circuit values differ depending on the car. 

The addition of the regulator improves the battery charging management.  The reduction of four to a two-pole dynamo, which probably occurred in the late 1920s, no doubt meant that there would be more periods when the battery is doing work running the electrical systems and the cut-out, which is not efficient, needs to operate more often.  I don't know how common the four-pole dynamo was in earlier cars, but it ceased being made for later cars.

The mechanical voltage regulator is quite good, and the driver did not need or have the option to manage the battery by watching the ammeter and switch charge rate, but the driver still needs to keep his tow on the throttle when idling in a queue in winter with the lights on.  No doubt the newer 2-pole dynamo was cheaper to make, using fewer assembly operations than the early 4-pole dynamo.  But the alternator has 12 to 16 poles, and a smaller, faster pulley sweeps about 6 to 16 times more poles per engine revolution and runs all the electrics even when the engine is idling by comparison.  The lead-acid battery has been very suitable for vehicles and electric vehicles for over 165 years. 
  • Auxiliary equipment became more viable, and A valve car radio of the time may require 6V, 5A (guess), which is more than the ignition system, so by adding accessories, the electrical system current balance could easily be very wrong, particularly if the car's electrics did not include a regulator. 
      • Some cars were negative earth, some were positive earth, a valve radio probably could cope with either, but other cars were 12V, and this sort of radio would not accommodate different battery voltage cars.  Heaters in the valves have different current ratings and usually run from 6.3V, but this issue could be resolved. 
      • Car radios could be made of high-quality cast aluminium with compartmentalised sections, a vibratory inverter for the high voltage section, radio and audio sections, and all had 0V bonding to the case by the shortest path at many points.  The valve base connectors had clips.  It would therefore be very expensive. 
      • The electrical system of modern cars has a high degree of interference screening and prevention, but at the sources of interference, such as the ignition, motors, and electronics.  So that the electrical systems of the car do not interfere with the in-car entertainment systems. 
    • The voltage regulator regulates over a range of current loading and allows the battery to charge as fast as the dynamo can deliver current.  But the battery is still used when the engine is idling.  The current winding in the regulator applies compensations;  A small increase in voltage when the charge current is higher,  A further increase when a lot of electricity is being used, as a compromise to somewhat compensate for when the battery is being run down faster when the car is idling. 
    Alternator supplies all the power all the time that the engine is running, including when the engine is idling.  Consequently, now car batteries rarely need topping up and can last at least a few decades, but they still provide voltage stabilisation and some over-voltage protection.  The electrical system must work from 5V to double 12V battery voltage, therefore 24V, withstand 60V and very fast high voltage spikes of around 500-800V. 

    The alternator has no brushes but uses slip rings that allow it to rotate twice as fast as a dynamo.  When introduced, they were rated at ~30A, but the Lucas ones, like so many things then, were not well-made at first.  They used less material than a comparable but slower-spinning dynamo.  By comparison, a dynamo is an alternator combined with a synchronous rectifier, formed by the commutator and brushes.

    Control box with voltage regulating, current compensation windings, a cut-out and fuses;

    Dynamo information UK company

    Post World War II cars also included an instrument regulator which used a hot wire and a bimetallic strip to open a contact when it gets hotter, thereby delivering a regulated mean voltage.  It powered the hot wire, fuel and temperature gauges. 

    Dynamo replacement - flash the field winding, to ensure that the field is magnetised a little and with the correct polarity.  That is with only the battery chassis cable connected, and the dynamo field wire F disconnected.  Connect a wire to the battery live terminal and touch it to the field winding F connection for say a minute.  This will create a big spark when you disconnect, which will hurt you if you are touching the dynamo field winding F contact; you have no reason to do that.  Finally, disconnect the battery, then complete connecting the wiring, then lastly reconnect the battery, chassis cable last.  You can prevent the big spark by connecting something resistive, such as a headlamp or stop lamp bulb, across the field winding first; this will prevent compromising the field winding insulation with back EMF generated. 

    The regulator's voltage can be adjusted by moving a screw or bending metal.  This wiring diagram/circuit with two fuses, but 12V instead of 6V before the War, is about what Lucas Industries made for British car makers after World War Two, but before the alternator system replaced them. 

    Coil winding insulation; pre-war, the enamel insulation gets brittle, cracks and falls off if the wire is moved.  Sometime post-war, probably in the 1950's the enamel was replaced with a type of plastic that does not become brittle.  That modern enamel insulated wire enamel melts and smokes off, so the wire does not need to be scrapped to remove some insulation to make a termination.  A soldering Iron may just about be hot enough to melt the insulation of a thin wire. 

    Replacing electrical systems with electronics to improve a vintage or veteran car's electrical systems. 
    Three brush dynamo - The third brush should be disconnected, and the field winding third brush wire connected to the chassis, thereby setting the power to its maximum and removing one brush from the system.  Take care of what the brush mounting spring does without a brush fitted.  I think the spring without a brush might touch the commutator, which would be a bad thing.  Alternatively, set the third brush to its maximum setting. 

    The electrical system then needs to be switched to negative chassis if it is not already.  That is the battery turned around; any electrical systems that are polarity sensitive, the ammeter and the ignition coil should be turned around.  Circuit AL-0060-04 will then reverse the dynamo and start generating.  But the other two circuits require the dynamo to be flashed.  Circuit 01 must not be connected, but circuit 02 can or should be connected to the Chassis and Field.  It will then stop a high voltage spark from occurring when you disconnect the battery from the field contact of the dynamo. 

    A college tutor would say, "If all else fails, read the instructions" 04 is a little less complicated and could start generating even if not all the installation steps have been carried out.  04 does not switch over from battery and dynamo power so precisely as circuit 02, but as far as protection against incomplete installation, the unit need not start up until a sequence of LED flashes and illuminations are acknowledged by button pushes.  Otherwise, circuit 02 is probably best because it won't start generating unless the instructions have been carried out, unless the car is already negative chassis, but in any case, the voltage must be correctly set. 

    Switch from a 6V to a 12V electrical system.

    Circuits -02 and -04 have settings to accommodate all four combinations of 6V and 12V dynamo and battery voltage.  

    Dynamo and battery charging;  The first set of diagrams, boost regulator with switch mode voltage clamp, in the PDF AL-0060-01? uses electronic components rather than a microcontroller, which shows the software functions that need to be re-created.  The second and fourth sets of circuit diagrams, PDF AL-0060-02 and -04, I have not chosen a microcontroller, or not chosen a suitable microcontroller, but many modest speed 48-pin types will work well.  It is best to avoid using a multitasking operating system, but write software and interrupt handlers.  The second circuit, the buck-boost regulator, is the best option, but making PCBs with provision for a small number of different components for either 02 and 04 circuits could be included on the PCB, but not fitted, which of those different components, depending on which circuit you choose to make. 

    The final version AL-0060-04 is almost identical, but for some unintended differences in where the Vboot+ net is either rectified dynamo after the buck-boost or from the battery rectified.  That is, after splitting -04 away, they then became more similar as I continued to develop both, plus I discovered the better SPV1040 start-up boost IC. 

    AL-0060-01A dynamo managerBoost Regulator to extended low RPM operation, this is a 6V analogue partial solution.  The current sensor at the dynamo is used for maximum power transfer optimisation.  In this circuit, the setting has to be found by trial, measurement and adjustment.  That current sensor is also used to provide battery cable resistance compensation and switch-mode power supply current feedback.  The boost circuit requires a little higher RPM in order to start up, then it will operate at a lower RPM than the dynamo system would normally.  CADSTAR 18 used.  The circuits are draft, and some of the component values are incorrect.

    The circuits have screening and overvoltage protection measures.  With or without these circuits, the car should not be run without the battery connected; the battery stabilised the voltage in both cases.  The changeover relay selects between the field winding power source, the PWM regulator or direct connection to the dynamo for starting power generation.  This will start without the battery, such as with magneto-electrics and would introduce a more certain power generation start-up because there is no semiconductor voltage step to overcome before the field winding is powered. 

    Electronics mostly start up above 3.5V, but the dynamo may produce less than 1 or 2V from the residual magnetism, so the field winding is connected by a relay to the dynamo initially.  When the dynamo is generating more than about 3.5V, the Field winding current is controlled by a pulse width modulator (PWM) to regulate the dynamo output voltage. 

    Field winding power and dynamo regulator.  The dynamo clamped and boost transistor is turned off for 10-100uS every 10mS or turned on for 10-100uS every 10mS in order to charge the synchronous rectifier ICs' power holding capacitor. 

    This does not provide all the power for the car's electrical systems.  At low RPM, the dynamo will stop producing power, but as long as the engine has been running at a moderate RPM and the dynamo has started up, it will continue to produce a little power at a lower RPM with this circuit.  In addition, this circuit clamps the dynamo voltage using 10mS PWM so that the battery is also not severely overcharged.  This still does not resolve all issues, and using LED lighting should help. 

    Because of the relay, the dynamo will start up even with a flat battery in a car with a magneto.  In case of a faulty wiring, the fuse should blow before any semiconductors are broken.  The field should be flashed with the cable from the unit disconnected, this is different to circuit 02 and 04 but the same as the original electromechanical system.

    But because the battery is connected to the output, if it were to become flat and low impedance rather than high impedance, this will stop this unit from starting up; this could be a safety feature or a disadvantage depending on the reason.  This is the same for all these designs, but differs from how a car with an electromechanical cut-out would behave. 

    Summary of this circuit version 01

    This circuit does not start generating at a lower RPM, the extra power region I describe in the graph further below, but it will continue to generate power in this extra power region once it has started generating at a higher RPM and continue to generate until the RPM drops to such a low RPM that not enough power is produced to over come all losses and deliver 7V to the field windings, with the boost SMP running. 

    There are, of course, losses in the system, so the charging system will stop producing enough power for itself when the RPM has dropped to where the dynamo cannot produce more than 100% of what the field requires.  This is better than the original system, where the field only ever got 20% perhaps more of the total power generated, so the dynamo would have stopped generating at a higher speed. 

    This circuit does not have the buck converter that recovers more of the power that is normally returned to the dynamo at higher RPM.  So, with all electrical systems running, the battery would be trickle-charged, not the usual fast charge that occurs after starting up without the lights on and high charge selected or what the regulator does.  Changing the lighting to LED lighting may reduce the power used and resolve this issue with this circuit. 
    ----------------------------------------------------------------------------

    Replacing filament bulb lighting with LEDs;

    Using LED lighting will boost the light level and reduce the current taken, but an automotive unit can include a power-wasting load, so that the unit matches the load of a filament lamp unit. 

    • You may be able to remove the dummy load, which is a bank of resistors.  The electronics should still operate properly.  That is, if one LED fails by breaking the open circuit, then all the LEDs of that circuit are turned off, which would, on a modern car, illuminate a dashboard warning light.  But you may need extra electronics to pulse-width-modulate drive the red stop/tail light function.  The PWM is either 100% for the stop light function or 5% for the taillight function running at 100Hz. 

    • The tail light function can not be created using a series resistor; even if the LEDs were to illuminate, their colour may not be legally correct.  On the other hand, all 12V car systems, including the lighting, should work down to 5V but not at their correct intensity. 

    • A 5W LED can be equivalent to a 50W filament bulb.  An Austin 7 was fitted with 18W headlamp bulbs.  Other bulbs are 3W but would be 5W or 20W for indicator lights now; these probably would not reduce as much as 90% using cheap LED units, and less wasteful units are probably not available. 
      • The LED drive may be by resistive drop (current source), therefore the efficiency could be reduced to 25% or perhaps or by switch mode power supply, in which case the efficiency may be 80%.  Either way, LED lighting is beneficial for saving power. 

    --------------------------------------------

    Buck Boost Switch-mode power supply to give more of the available power when required;

    The Dynamo's power output can be at least tripled at high RPM and start producing power at a lower RPM without having to have been running at a higher RPM first, unlike circuit 01.  As in the previous circuit, the power remains the same at the stated dynamo rating and RPM. 
    • This is not more power from the dynamo, but instead of returning potential extra power back as motive force, so that the dynamo motors a little.  That is ordinarily, the turning force to the dynamo would have dropped with increased RPM, and the power taken remains unchanged.  If all the unused power were used, then the turning force required would not drop but stay the same. 
    • Whether a unit is home-made or manufactured, this would be an after-market product, so it does not need to comply with each of the different manufacturers' own standards they impose on their suppliers, but it does need to work with double battery voltage, 12V on a 6V or 24V,  on a 12V car electrical system. 
    • The voltage control response time is slower because of the diode across the field winding, so the output crowbar will necessarily do more work, consequently.  That is, the crowbar will operate normally when driving the car, and auxiliary circuits are turned off. 
    • But the average field voltage must be limited to the original rating of the dynamo, 7V.  Therefore, the dynamo voltage could rise to at least 21V as long as the output current is limited to 13.5A (actually ~13A = 11A + 2A, the field current).  ~13.5A is the rating of an D45D dynamo, 11A is the figure given by Austin.  0.5A for the third brush adjustment range, perhaps.  The original system probably delivered 8V to the battery, but what I propose is 7V to the battery but for more of the running time during a journey. 
    • That is, at 3600 RPM, 3x the specified RPM and outputs, the dynamo's output voltage can be allowed to rise threefold above the specified output voltage, at least 21V, probably 30V.   But clamped to 12V in this case rather than ever reaching 30V or so. 
    Other models and car makes used up to about a 125W dynamo; some were 12V.  Post-war, 1945, dynamos increased to 400W, and bigger cars or higher wattage dynamos. Subsequently, alternator power and more electrically driven systems have caused the power budget to increase.

      Option (2) Nexperia - simplified buck-boost converter, this circuit is duplicated, running in parallel, multi-phase, to minimise the electrical noise generated.  This diagram is a general buck-boost converter, so it does not show the field winding management

      Suggested control strategy;
      • Run the field winding so that the Dynamo produces the correct voltage, but then use the buck converter to reduce the voltage to 7V if there is excess voltage. 
      • If overvoltage is being generated, use clamp mode to reduce the dynamo voltage.  That is the low-frequency chopper clamps the dynamo voltage whereas the high frequency drive boosts the dynamo voltage and an MPPT strategy for optimum power transfer needs to be used with either buck or boost mode operation. 
      • To start up use the SPV1040 boost regualtor to run the field as far as possible then divert the power to the gate drivers and use the buck-boost, boost regualtor to to power the field and at some point start taking work away from the battery, eventually charging instead. 
      The buck-boost circuit version 2 can.
      1. Reduce a 12V dynamo to 6V car electrics, but the unit can not provide extra power below the original dynamo start-up region.   This combination is not supported. 
      2. Increase the 6V dynamo to 12V electrics, and it can provide extra power at lower RPM.
      3. Run an all 12V system or an all 6V system, and also has all the features.
      Likely buck-boost modules or ICs that may suit with some additional circuitry
                                                                Vin        Iout           Note                                                                1 off
      ISL81401/ISL81601/ISL81801   4.5V  40V/60V/80V   controller                                                        £3.60/£6.50/£9.70 
      LM5118                                        3V    75V                     "                                                                    £4.70
      MAX25431/MAX20048              2V    36V                     "      initial start 4.5V                                    £4.25/£7.20
      LTC3789                                      4V     38V                    "                                                                    £10
      TPS55288                                    2.7V  36V   <16A   Internal o/p transistors external i/p transistors.  £7.35
      LTM4712                                     5V     36V   6A(6Vin)  12A(12-36Vin)                                             £44
      Microcontroller   Is cheap and has plenty of flexibility, but software needs to be developed. 
      • Input crowbar over-voltage protection across the dynamo is required, such as a transistor or gating to turn on the two input transistors. 
      • Power the field winding and the power supply from the battery, but ensure that the dynamo is generating enough power to power the field winding. 
      • Use at least two modules or ICs running multi-phase to minimise switching noise. 
      Evaluation boards that will take the Field Winding current from the battery;
      EVAL-LTM4712-A2Z will provide 24A at 5V-12V input and up to 48A for £160,
      Or, DEMO DC3189A for LTM4712 36VIN, 6-12A Buck-Boost for £54
      Evaluation boards that won't take the Field Winding current from the battery;
      Or, TPS55288EVM-045 or TPS552882EVM-400kHz, 3-5A maximum output may be enough £94 

                                                                  
      Plus, in addition, veroboard to add fuses, an input over-voltage clamp circuit Field Winding drive by pulse width modulator (PWM) circuit and a low-voltage field start-up circuit.   The circuit below is the most refined, although there is work to do resolving issues and replacing parts that are placeholders with more suitable parts. 


      AL-0060-02A dynamo manager, Buck-Boost Regulator to extend the low RPM operation - 6V or 12V or combination solution and fast charging with lights on, if necessary, at higher RPM.  CADSTAR 18 used.  Some of the components and their values are not resolved yet. 

      This is not quite an interleaved dual-phase, but it is dual-phase, and it shares some of the reduced EMC benefits.  Another sheet has the second phase; it is a partial duplication of this sheet.  A better EMC profile may be achieved by using one of the Buck-Boost ICs with extra features for EMC and efficiency.  The microcontroller is still used to optimise the power transfer and the field PWM control.  There would be benefits in changing to GAN MOSFETs in higher operating frequency and reduced gate switching noise, and reduced PCB size.

      Parts of the Field drive circuit sheet are similar for both the boost-only and the buck-boost circuit. 

      It took a while for me to work out this function, for which I have a few good, simple solutions.
      • The Bipolar Junction Transistor (BJT) solutions have less protection, but it should be enough normally.  A variant need not require a battery, but won't start up unless the remnant magnetism is enough for the dynamo to produce 1V. 
      • The electromechanical relay will blow fuses if badly wired, but it is a better solution, starting up from a fraction of a volt out of the dynamo.
      • Two MOSFETs back-to-back resolve most protection issues.  It may run from Dynamo power or battery power via the ignition circuit, but in any case, the field winding power comes from the dynamo's remnant magnetism in the field iron. 
      • Boost regulator is good because a few solutions will start up from about 1V and then power the main buck-boost boost regulator.  But the best is SPV1040 solves most issues because it will operate from 300mV to 5V, and will power the microcontroller and will start up from <400mV from dynamo remnant magnetism.  That is, it should work reliably with a lower voltage 6V system.
      That is, if the battery is flat, the dynamo should start generating if the car uses magneto ignition.  Consequently, the dynamo will start up and run somewhere in what I describe as the extra power region of the graph, further below. 

      This circuit 02 has now been developed and is probably the best of the three circuits.
      • The cut-out function is more precise using a rectifier diode than circuit 04, which uses more parts and needs a lot of software development to do similar. 
      • It will start generating power at a lower RPM or start up more quickly. 
      • This circuit, by default, does not remagnetise the field negative chassis, unlike circuit 04. 
      • If it is necessary to reverse the car's electrics, including the field windings, the unit should be connected to the chassis and the field first, at least so that the snubber diode protects the field winding and the installer from high voltage spark when the field is disconnected from the battery. 
      This circuit is better than circuit 01, and circuit 01 should be put aside. 

      There is now just one field 
      driver; it runs from the power produced by remnant magnetism in the dynamo's field iron, which is boosted to a usable voltage.  Startup is different to the first circuit, and it has other protection.  It starts up in the extra power region if there is adequate power available in the dynamo.  At high RPM region, the dynamo can provide more of the power it is generating rather than returning that power by causing the turning force to drop because the dynamo is also motoring, unlike the original car system. 

      This circuit is reasonably well protected and should stand flashing the dynamo and prevent arcing that would compromise the winding insulation slightly.  The 5V0start net powers the uP and is monitored, so that no more than what is available is taken to drive the Field winding by setting the PWM.  The dynamo is monitored so that no more power is taken than is available unless the overvoltage clamping function is being used. 


      st.com community advise me that I can reduce R1 and R56 to 2K I have reduced those resistors to 2K2, which improves the gate drive over using higher value resistors surrounding the SPV1040 boosted supply.  I have also added a diode between Vdynamo+ and Vboot+ nets so that the dynamo output can continue to increase, but without using the start-up boost supply or needing to supply the car electrical system at the same time; this diode is not beneficial (this came from circuit -04) when the battery is in good order. 

      No power is taken from the ignition circuit other than to run the status LEDs.  The Red/Amber/Green LED will flash slowly as a warning, not a fault, if the battery deep discharge recovery feature is turned on, but that feature only doubles the battery voltage does not go any higher, but at a very low current <0.5A.  So that normally the battery and other circuits, if used, take more power, and the voltage drops to 7V or less if that is as much as the dynamo can deliver optimally. 

      It took me a while to develop the Field Drive function.  Here are some alternatives that may have weaknesses, AL-0060-03A.  A problem arises that the dynamo will not generate unless D and F are connected together at start-up, but there is little voltage generated by the dynamo for the electronics to start up and turn on the connection.  The relay in AL-0060-01? resolves this issue, though it will build up power slowly, just like a car's standard system would anyway.  The electronic boost regulator increases the voltage to 7V, drives the field winding with up to 100% of the dynamo output.  The voltage therefore builds up more quickly if the dynamo is rotating fast enough, but that is it will start generating at a lower RPM than the original system could.  This is the extra power in the graph below: the anticipated advantage of AL-0060-02a, or AL-0060-04a.  When the dynamo is running in its extra power region, and generates a surplus that is delivered to the car's electrical systems sooner and at a lower RPM. 

      A 6V dynamo, based on what the web tells me, a 6V dynamo will produce about 1V from the remnant magnetism in the iron of the field magnets.  This start-up circuit powers the microprocessor and the status LEDs; then surplus becomes part of the Vboost+ net that also supplies the buck-boost regulator MOSFET gates and the field current.  Only the SPV1040 boost regulators listed below will start up at a low enough voltage to be relied on to start up on a car with a magneto and a flat 6V battery.  The complication, though, is that these ICs only produce 5V, so I have included a circuit that only takes pulses of current on the forward conversion cycle of the IC using a voltage multiplier diode-capacitor network, but with an output resistor.

      A flat battery can be high impedance and can be recovered by the deep discharge recovery method by charging it from a high voltage, say 5 times the battery rating, until it starts to draw current, which may happen after a number of hours.  Otherwise, it may recover after a number of weeks of charging normally.  Such a feature, if included, would require that it be switched off whilst any electrical system of the car is required, and may be of negligible value to the car user.

      If a flat battery is low impedance, which can also occur if the acid level has dropped a lot, then it's been topped up.  Then, putting some current into it will restore it again.  But if a plate has buckled and shorted, then the other cells will produce a lot of hydrogen, which is dangerous. 
      • Boost regulators that start up from a lower voltage but only work to the lower 5V.  That may have other features, such as MPPT managers.
        • LTC3105 0.4V to 5.5V. may start at (225mV) 1.1V due to #shutdown threshold
        • SPV1040 0.34V to 5.5V may start at 300mV (increase 270mV decrease to 140mV)
        • SPV1050 0.58V to 5.5V <70mA or buck-boost from 2.8V to 18V <30mA has many other features. Boost works down to 150mV after starting.
        • bq25570 0.6V to 5.1V works to 100mV 110mA includes a battery charger.
        • bq25505 similarly 600mV start-up, 230mA.
      The MPPT function ensures the boost regulator starts up without stalling, trying with a very low start-up voltage.  st.com calls the MPPT strategy "The perturb and observe algorithm is based on monitoring either the voltage or the current supplied by the DC power source unit so that the PWM signal duty cycle is increased or decreased step-by-step according to the input power trend."  Similarly, I propose for the dynamo management, trial and error, similarly, but also storing the optimum power characteristic and using a combination and introducing a slow ripple, to improve the characterisation and use the characterisation to correct for noise in the electrical system.



      Permanent magnets to replace the field windings. 

      The field could be continually magnetised using modern high-power permanent magnets.  The over-voltage clamp function will then regulate the output voltage using PWM running at 100Hz.   These circuits accommodate this option.  You leave the field winding's output disconnected.   The status LEDs will not indicate correctly, because there will appear to be a fault at times, causing a flashing green LED.


      Final circuit -

      The field windings can be powered from the battery, which will reverse the dynamo polarity as part of how it works.  Withstand flashing the field, although that is not required, will start the dynamo if the car has magneto ignition and the battery is flat; the dynamo should start generating power.   A deeply discharged high impedance state battery should be recoverable on a magneto ignition car, but there is a risk of the unit if used in this mode, the unit may damage other components in the electrical system, so the mode is only available by switch option, maybe using the low charge setting? 

      The design AL-0060-04A encompasses AL-0060-02A, but with footprints for parts that can be added or removed to try features.  That is, the unit will start up anyway, reverse polarity or remagnetise, dynamo,  on battery power, flat battery on an early type magneto car.  Also has an ammeter display via USB charging port, because of the battery power option, which would have otherwise caused a bad cut-out operation.   This solution requires more software development, which could be avoided by adding more parts.

       AL-0060-04A This diagram shows the input and output power and switch options.  It is similar to all three draft circuits. 

      Power for the field windings is now taken from the dynamo, but can, by fitting components differently, be taken from the battery.  Therefore, the low-voltage boost start-up function has become an optional feature rather than a necessary circuit.  Otherwise, the circuit is similar to -02. 

      The connectors should differ, and the power connectors should be pluggable and screw in types.  The LED should be an assembly with a dashboard-mounted unit, cable and connector.  A junction box should also be offered that will replace the unit with the old cut-out regulator and fuse box units, accepting the same connectors, but for the generator lamp, which could be left in place regardless of which new or original system is used.  The junction box should also drive the Red LED, as the filament lamp would have worked, that is, have an anti-parallel diode and series resistor to make it compatible, provided the system is not switched to a positive chassis. 

      PCB switches;
      • The switches set -
        • 6V Dynamo, 6V Battery
        • 12V Dynamo, 6V Battery - This is a poorer option because there is not always 12V for the field winding at low RPM. 
        • 6V Dynamo, 12V Battery 
        • 12V Dynamo, 12V Battery.
      • The up and down buttons set the battery terminal voltage to compensate for the cable resistance.  So that the battery terminals' voltage is 7V when the dynamo meets the battery's need, when the generator light is green is on. 
      • The last switch could be used to offer a simple RED generator light.  Except under a fault condition. 
      Dashboard;
      • The High charge (F2) or Medium charge (F1) Contact and pulled up to B+, then the low charge is not selected.   Low charge could be used to turn on flat battery recovery mode for a low or high impedance battery fault.   Otherwise, wire one of the unit's connector terminals to the ignition, and the feature will be turned on.   That is to bypass the warning and force battery recovery mode. 
      • The dashboard generator LED.  Flashing slowly indicates set to flat battery recovery mode is running. 
      • RED - Not charging, 
      • AMBER (GREEN and RED) - charging but not meeting the need. 
      • GREEN - Meeting the needed, and the battery voltage is correct. 

      • White or Blue LED - Extra power, buck mode, or extra power at low RPM, boost mode, is being generated.  If an LED is fitted. 
      I have not included another status LED, but a white or blue LED could be added to the dashboard to tell the driver that extra power is being generated.  I am not recommending this option; it adds clutter, but the light could be put on the unit, although the ammeter advises the driver anyway. 

      Error conditons displayed by fast flashing LED colours;
      1. Dynamo has not started up, so maybe the Field needs to be flashed to reverse or magnetise it. - Fast red LED flashing.

      2. No battery detected,  fuse or wiring fault. - Fast Green LED flashing.

      3. Open or shorted field winding, fuse or wiring fault. - Fast amber LED flashing. 

      4. GREEN and RED - Flashing alternately and slowly, Fault, wrong or low battery voltage setting.  Such as set to 6V, but a 12V battery was found.  But the cause may be that the battery voltage is very low, and in that case you can use the Low Charge setting to recover the battery, by in this case using the battery voltage setting and continuing to run. 

      AL-0060-04A - Three options for the bootstrap power supply.  Option B works the same as a modern alternator system and is the same as circuit -02.  Option C has been added to circuit -02. 

      The options for the bootstrap power supply are: -

      A - Uses the battery or dynamo to power the field winding.  The disadvantage is that the current cut-off is not precise, so at times battery power will be taken or running current not delivered when it could be.  The inaccurate cut-out function was resolved by adding a battery current sensor, which gives a USB power and ammeter display option as well.  By turning the field off for 10mS, say every second and seeing if the battery charge rate increases, you can determine if the field drive is taking more power than the dynamo is delivering.

      B - Only use the dynamo to start generating.  The same as circuit 02 is a safe option; the ammeter function is not required. 

      C (not shown) - In addition uses dynamo power when it is higher than the battery terminal voltage to start up.  This works like the electromechanical cutout and will deliver a much higher current into the electrical system with no voltage, such as a flat battery and all the lights turned on, or a shorted electrical system.  That is, it could be harmful, but it need not be used other than to ensure that there is power for the status LED so they can flash at a fast rate to show a fault.  The output current could be sensed by adding INA745x, INA780x, or INA740x integrated current sensor.

      It turns out that the boost regulator from <400mV resolves many issues and should allow the dynamo to build up to full power more quickly than it would have originally.  So there is little benefit in using battery power to improve the start-up time.  Because this design flashes the field by default anyway that it might be thought better that circuit 02 be finalised instead.  The Vboot net is a common power supply with the main output OR with the battery OR dynamo start-up boost, but -02 does not include the battery; the ignition circuit in that case was only used to drive the LED status lights. 
      • The microprocessor placed is not the optimal choice, but it shows that a 48-pin microcontroller should fit. 
      • The unit should withstand starting with jump leads, an inappropriate connection to the field or the dynamo without blowing the fuses. 
      • The unit starts up with < 0.4V generated from remnant magnetism in the dynamo if the battery is flat, such as starting on the crank, in a car with a magneto. 
      • The field is powered from the battery when there is ignition power or the dynamo is generating.  This is what is different to circuit 02; it means that the dynamo will start producing power more quickly and that the unit will also correctly magnetise the negative chassis of the dynamo if that has been changed or become demagnetised.
      • If the dynamo is not generating, then the field is pulsed on from the battery periodically to magnetise and start up the generation of power.   This is almost certainly not necessary hence option A requires more circuit and software complexity.
      The original unregulated power system was likely to overvoltage if the battery is deeply discharged, which will cause the battery to recover more quickly.  The electronic controller could recover a flat battery by operating at high voltage if the current taken is low, say <0.5A, say 200mA, but it is liable to cause lamps and non-automotive parts to break in the transition from high voltage battery recovery to normal voltage or break them anyway.  The battery voltage would drop back to normal 7V when any auxiliary is turned on.  Therefore, the option can be enabled by, say, setting the high charge switch on the dashboard, if the wiring allows this. 

      Circuit -02 is a good option, but Options B and C, but not A, are probably the best option if the full dynamo power is not delivered to an electrical system showing shorted, no voltage.  Therefore, the status LEDs can be powered and flash at a fast rate to indicate the fault.  The circuit is adaptable because components can be fitted and removed to try options, then the final version is made with a few parts fitted with just changes to the bill of materials.  


      Conclusion.

      The circuit has been developed in stages; I have explained some of the improvements with each stage.  There are still PCB footprints and refinements to do.


      Graph showing expected benefits for each of the circuits AL-0060-??? is not to scale, and curves may be the wrong shape. 

         - Standard dynamo electrics, electronic or electromechanical AL-0055-02?  The exponential line shows what could happen without the battery, and the voltage runs away in the earlier car electrics, AL-0055-01? Beyond 6 or 7V, the runaway would be limited to just voltage with no further current increase.

          01 - Boost mode benefit.  Once the dynamo has started generating will continue to produce reduced power at a lower RPM, the Boosted region and in this case, takes more of the output to drive the field, thereby producing a little power in the Extra region marked where there would have been no power originally. 

      The simpler boost mode circuit switch-mode power supply provides, to increase the output voltage to 7V or at least as much as the maximum power transfer from the dynamo will provide, 13.5A or less in this case.  This will also deliver reduced current at low engine RPM, such as when idling, rather than cutting off and stopping the generation of any power as it would have.  Could be as high as 5A = 13.5A / 2 - 2A, @ 50% specified 1200 RPM, maybe not enough to run the ignition (2A Morris), ~1A = 13.5A / 4 - 2A, at 600RPM.  That is what the first circuit AL-0060-01? provides, plus overvoltage clamping by 100Hz PWM. 

          02 - Buck mode benefit.  It will produce more power or can take less current at higher RPM. 

      A buck-boost in buck mode switch-mode power supply in buck mode to reduce 21V but take less than the maximum available at 30 to 40V at the dynamo to 7V will increase the available current more than threefold, 40A, limited by transistors and other parts used.  This is the additional benefit that the second circuit AL0060-02? provides. 

      Both circuits also provide a PWM over-voltage clamp that perhaps would be used when the output voltage continues to increase past, say, 8V.  This should lighten the workload on the battery a little. 

          03 - These are field drives and startup power supplies that I have worked on but put aside.  I may come back to them if what I have chosen is not working out.

      I have also included a transistorised regulator and diode as a replacement for a mechanical cut-out and regulator.  The significant point is that the snubber (transistor protection diode) slows the response time of the control loop.  So there will be longer periods of overvoltage generation before the loop has responded than the electromechanical regulator performs.  This could be resolved, but it is an accepted limitation of a car's electrical system, lost in the other compromises in car electrical systems. 

          04 - Extra power due to the dynamo staying in this region because the battery accommodates fluctuations.  At lower RPM, the Dynamo will produce or start to produce power even in the extra power region, using battery power to start up in that case.    
       
      The third circuit, AL-0060-04A, the separate field power is removed and connections made to the battery, thereby using the feature of the battery to stabilise all the power systems of the car.  That is the field winding being driven from the battery, but only when the dynamo is generating enough power to power the field.  If the dynamo is not providing enough power to supply the field, then keep trying periodically until it does.  This should prevent the dynamo from ceasing to provide power at its extended lower range because the battery will smooth out power fluctuations that could bring that about.  That is, the circuit now does not have the latched-on can-unlatch issue that may arise at low RPM in the other two circuits.

      Overall, the more of the dynamos available power is available; consequently, the battery's workload is reduced.  The stability that the battery provides makes the whole electrical system work better.  That is when the software is working well and the components, primarily the dynamo, have been characterised by the microprocessor.  The flat battery and, magneto startup feature need not be fitted, but may not work in the last circuit AL-0060-04*, which has a greater voltage drop between D and F connections, but is shown anyway. 

      Completing and sending this design for manufacture would be expensive, 

      Costing thousands of pounds. A workaround would be to use an Infineon or other maker's board, say 12-60V 10A or 18A single-phase solar panel power supply board and adapt it.  It need not be the newest CoolGAN evaluation board because old technologies are still very efficient.  Then adapt it, which Infinon say can be done using different magnetics and transistors, but I guess two or three sets of boards would do the job with fewer changes to the board?  
      Use manufacturer's evaluation boards for microcontroller, SPV1040 regulator, plus veroboard for the field driver and other functions.

      A cheaper and easier option use already available evaluation boards, such as;

      Infineon solar panel optimiser
      OR
      • 15 to 60V needs to be adapted to optimise over; 2V to 8V or 4V to 16V
      • An internal power supply of 12V needs to be generated by a small buck boost regulator to 12V
      • Infineon advise that the wound components also need to be revised.  Though I think you can get by with what is fitted.
      • Other evaluation boards for SPV1040 or SPV1050 in boost mode need to be used.



      --------------------------------------------------

      Magneto for ignition, plus lights, plus battery charging;


      Villiers motorbike engines, magneto's - publications ~1950;

      1. Magneto with two lighting winding types and the ignition pair of windings at the top of the picture.  Pictured is the four-pole type, but a 6-pole with 6 lighting windings was also made. 
      2. Diagram the ignition coil with low voltage and high voltage windings, contact breaker points, and the capacitor.  Plus two coils for lighting, see top and bottom, 
      3. Diagram showing the working of the ignition magnetism, but the HT winding and the capacitor are not shown;  My text, a b c,  explains different aspects of the spark generation cycle.
      a) Contact open, is closing, poles are aligned, so the magnetism is at its maximum, 

      b) Contact is closed, magnetic polarity is changing, which causes a high current in the low voltage winding, and that current tends to resist the magnetism from changing. 

      c) Contact opens, magnetism rapidly changes, the capacitor slows the rapid rate of voltage rise, so that the spark occurs in the spark plug but not the contact breaker points. 

      I do not have experience with a 1920s car, but my 1970s motorbike, which used a selenium bridge rectifier, had no regulator but a switch to connect higher current windings into the circuit when the headlights were turned on, but it ran the battery down if ridden using the parking lights.  The battery was then used in the conventional Kettering ignition system, which also includes a current-limiting series resistor.  That is, it was different to a Villiers motorbike engine.

      Some Villiers engines had a selenium rectifier and a battery for the parking lights from 1930.  Riley was still using a magneto on a few of their cars until 1932.  Austin stopped using a magneto sometime in the late 1920s.  Cars with a starter motor, a battery that required charging, also had a dynamo and a cut-out. 


      The simplest spark ignition uses a moving fixed magnet and a stationary high voltage coil wound on soft iron.  A blunt wedge edge rotating magnet, and a stationary blunt wedge edge iron with the high voltage coil.  Parts pass each other closely, generating a high voltage spark.  The engine, such as a lawnmower, has to be cranked quickly in order to start. 

       
      Two videos;
      1. This large, low-revving veteran engine had a sprung-loaded magnet which was released on a trigger, moved the magnet rapidly passed the coil.  You might be able to see operating in this video at 6.50 minutes.
      2. Earlier spark ignition describes the contact break inside each cylinder method. In the video description of modern capacitor discharge ignition, I have put a better explanation below.  
      After-market electronic ignition units made by Jermyn Industries in the 1970s, also known as capacitor discharge ignition, because energy was stored in a capacitor, and the coil was used as a transformer, its inductance was not used to store energy for the spark.  I don't think car makers ever used this system, but they did use the magnetic contactless points system.
      • A magnetic sensor instead of the contact breaker points - this could be unreliable,
      • A two-transistor saturated core high frequency oscillator and transformer to step the voltage up to about 300V - this circuit could be slow to restart, preventing the unit from working at a higher RPM.
      • A capacitor was charged and then discharged into the coil, which was now used as a step-up transformer - the discharge was by an SCR, which was reliable.
      • Because the coil used as a transformer has leakage inductance, some of the potentially greater electrical interference would be limited. 

      Modern ignition systems probably do not use the inductive discharge Kettering system but have an oscillator circuit driving a small step-up transformer to produce a very short burst of high voltage sparks.  Or it could be a very high current, low voltage pulse and a step-up transformer?  Placed on top of each sparking plug, thereby containing the spark current pulses' path more closely with the spark plug and thereby reducing electromagnetic interference. 

      Non-electric spark ignition; using compression ignition (diesel) and a glow plug, before that, hot tube ignition. 

      Hand cranked starting;  You did not always need to crank a veteran car to start it.  It might start when the trembler coil (spark box) was turned on, but they did break a lot of people's thumbs or arms, hand-cranking them.  One car in the Beaulieu motor museum had injured 10 or so people in over a century of the car's existence.
      AL-0060-03A Electronic Dynamo regulator and rectifier. This does the same as a simple electromechanical regulator and cut-out, but without the two current compensation windings. The circuit is similar to an alternator regulator.  

      An alternator has three-phase windings, A 6-diode rectifier stack for the main power, plus another 3 diodes for the field control and driver circuit, so there would be no output rectifier diode.  But the voltage sense circuit uses a zenner diode and does not have a voltage sense wire to the battery.

      The Mini Metro was launched in 1980.  Cars had now become what the Lenton sport bicycle already was in 1946, a vehicle you could use with just some minor servicing points to observe and deliver when new without faults. 


      In the 1970s, people bought European car makes because of the better quality, but even though those were not delivered fault-free, the 1975 New Audi 80 now had front wheel drive, dual circuit brakes, and road handling like a Mini.  But my father's car had a temperature gauge that indicated too hot, like others the dealer had, a not worked out two-button control of the two sets of headlights, so off was with one button in and the other out, and both on could be another or the same combination of buttons in and out.  Lovely car, though similar to the BL Allegro, both delivered new with wiring faults.

      ------------

      Earlier steps towards easier travel

      After Richard Trevithick's high-pressure steam, coach of 1801 and his steam train, came velopede an early type of bicycle.

      The Karl von Drais of Karlsruhe, the human-powered bicycle, was an early step forward, being a two-wheeled velocipede of 1817 rather than his earlier 4-wheeled, or many subsequent developments that failed until about 1860.  The German eurocoin minted in 2017 to mark this inventor's significant development.  But the Veteran Cycle Club magazine's spring 2025 article does not believe the motivation for the invention was a shortage of horses around the time of the Tambora volcano or a concern over climate change. 



      Steam Coach services started being developed.  The picture is one of Goldsworth Gurney's steam road coaches from 1827, long before pedalled or motorised private vehicles The first vehicle was Richard Trevithick's high-pressure steam coach of 1801 Mercedes Jellinek, whose name was used by Benz for his brand of car, to improve its sales in the USA, according to J Leno's TV show, if I understand correctly.  Pictures from the book ISBN 0-9510625-0-6.  The first steam car was made in the UK and another in the USA between 1800 and 1810

      De Dion, Panhard, and Daimler were also early car makers.  The steam train services started in 1825 in the UK.  The hot air balloon travel goes back to the 18th century. 

      18th-century steam engines were made by heating, hammering metal and using a stuffing box filled with cloth and graphite to somewhat seal between moving parts.  These engines were used for pumping water often, but very inefficiently.  By comparison, a bicycle's frame and transmission efficiency had to be and it is very high.  James Watt developed standardisation and methods of accurately making things, such as making three flat surfaces by grinding the three surfaces against each other in turns, from my school metalwork classes.  That is the wealth that the European nations had accumulated by conflict and exploration allowed wealthy of us to finance or develop technology, inefficiently though, found all over the world.  That is enabling the capabilities humans always had. 

      Steam engines date back to about Hero's engine, with a history spanning over 2,000 years.  An 18th-century French vehicle and a 17th-century Chinese toy are steps toward the first vehicles. 

      ---------------------------------------------------------------------

      Other developments

       
      An owner's manual shows you
      how to service nearly every-
      thing on the car.  Car makers
      stopped publishing these, but
      The Haynes Manual replaced
      them also show you how
      to fix everything on the car.

      After 1945, car engines got the improvements that had started in the 1930s, first in Jaguar Cars, the Rolls-Royce Merlin engine, then the designer went to Austin and other makers.  The swirling, turbulent gas chamber design, OHV, better fuels, and higher compression doubled the output power.  Companies merged, got big, and management lost connection with the workers; bad industrial relations resulted, and a few companies made a lot of bad headline news.   
       
      Up until 1979, car ignition contact breaker points would need to have the high point (spike) filed down, then the gap set every 3,000 miles.  Better oils that need less frequent changing, but brake hydraulic parts and fluid are rarely replaced as frequently as recommended, which is 20,000 to 40,000 miles or every two or three years.  Otherwise, cars needed much less owner maintenance and only required management of the gears, which people liked.  Hybrid cars manage the transmission more efficiently.  Now self self-driving cars are starting to do everything in 2025.
       
      When the Mini car became available, it soon became a people's car like quality bicycles made by Raleigh.  Its 850cc engine was still 3-bearing but now OHV, SU carburettor, forged crankshaft, and double the power output at 34BHP to the Austin 7.  Owned by ordinary people as well as the very rich.  Nations used to pride themselves on having good services, people took pride in working for a government service, and everything well made for their people.  Many manufacturers, including big companies, still pride themselves on making good quality things, but talking about profits is not vulgar any more.  The Austin 7 cars were well known in sports, and the Mini cars were exceptional in rallying.  And very good sports bicycles used to be made to be used on ordinary roads, whereas they are now uncomfortable on ordinary roads.  One of the differences between a Raleigh Record Ace used in competition and the Lenton Sports is that the crank height is set 1" higher off the ground in the RRA.  Both bikes should be good enough to cover 1 km in a minute. 

      --------------

      Oil companies would send anyone who wrote, asked, booklets and lubricating charts in the 1950's such as the one pictured right.  Here are some more: FordMorrisRiley, and Rolls-Royce.  Most things used to be made to be repairable, and ordinary people would be more empowered by having repaired things. 

      Note: * The Car's life was improved by adding oil and air filters to reduce engine wear. Later improvements to oils also meant thinner engine oil with both better longer longer-lasting lubrication and better engine efficiency.  In the 1950s? CC Wakefield Ltd.'s  Castrol brand multi-grade oil became available, so summer and winter oil changes became unnecessary and over subsequent decades, car servicing frequency was reduced to once a year.  The number of types of oil was greatly rationalised at this time, and booklets like these had amendments reflecting the changes.  Many types of vegetable oil had stopped being used early in the 20th century. In the 1970s, improvements to carburation were made using a bimetallic mechanism to redirect air intake from the hot air flowing over the exhaust manifold to get the engine running at optimum temperature quickly, thereby improving efficiency and reducing cold engine wear.  Consequently, a small car's engine would last 15,000 to 25,000 miles, increased to 100,000 miles and now even longer, and engine, de-coking, and reconditioning are not so common. 

      Modern thin engine oil is very good for veteran and modern bicycles, so that you don't need to oil the bike so frequently, as once every 100 miles or every week.  Use grease on the bicycle's cables and slides, and levers rather than oil. 

       
      Riley 9 was a very desirable car with its pre-selector gearbox plus automatic overdrive, so you can accelerate from stationary going through three or four gears before touching the pre-selector lever, just the selector pedal once.  The car has an automatic clutch, so you only need to use the selector pedal gearbox clutch for hill starting.  The wiring diagrams look nice, but are difficult to follow.  The designer must push the draftsman to make the circuit clear.  That is, avoid 4-wire junctions, lots of wires crammed together rather than grouped by function or labelled at the points they join and leave a bus. 

      My father's opinion of driving a pre-war car with synchromesh was that, as long as you waited for it, it was slow in operation but nicely paced and easy.   Imposing an un-paced, calm driving style, unlike modern life which those cars were not designed for.