Did you ever wonder how the mechanical voltage regulator — that big black box wired up to the generator on a car from the ’60s or before — worked? [Jonelsonster] has some answers.
For most people in 2026 an old car perhaps means one from the 20th century, now that vehicles from the 1990s and 2000s have become the beloved jalopies of sallow youths with a liking for older cars and a low budget. But even a 1990s vehicle is modern in terms of its technology, because a computer controls the show. It has electronic fuel injection (EFI), anti-lock braking system (ABS), closed loop emissions control, and the like.
Go back in time to the 1970s, and you’ll find minimal electronics in the average car. The ABS is gone, and the closest thing you might find to EFI is an electronic ignition where the points in the distributor have been replaced with a simple transistor. Perhaps an electronic voltage regulator on the alternator. Much earlier than that and everything was mechanical, be that the ignition, or that regulator.
The video below the break has a pair of units, it seems from 1940s tractors. They would have had a DC generator, a spinning coil with a commutator and brushes, in a magnetic field provided by another coil. These things weren’t particularly powerful by today’s standards and sometimes their charging could be a little lackluster, but they did work. We get to see how, as he lifts the lid off to reveal what look like a set of relays.
We’re shown the functions of each of the three coils with the aid of a lab power supply; we have a reverse current relay that disconnects the generator if the battery tries to power it, an over-current relay that disconnects the field coil if the current is too high, and an over-voltage relay that does the same for voltage. The regulating comes down to the magnetic characteristics, and while it’s crude, it does the job.
We remember European devices with two coils and no field terminal, but the principle is the same. There is never a dull moment when you own an all mechanical car.
inb4 old farts come complaining about how modern cars all suck and fully analog 1970s station wagon with a 5L V8 engine developing 100 HP is the peak motoring because it has the ability to turn something that in a modern car would just be a minor incident into a major accident with injuries and possibly fatalities.
This comment is a linguistic treasure trove. You could write dissertations on the various things going on here. It reminds me of Japanese grammar in the way that half the clauses are just left off and the meaning is implied. Come in mid conversation and you have no idea what’s going on.
To which the 1970s Volvo says, oh did I make contact? Sorry, and drives on like nothing happened.
My farts are so old they smell of formaldehyde, but you’ll never catch me gazing lovingly through my rose-colored driving goggles at the automobile designs of (holy hell) more than half a century ago.
Do I think it’s unfortunate that modern cars are so complex and nigh-impossible to user-service and -maintain? Yes, in the same way I think it’s unfortunate that modern computing devices have lost nearly all of their modularity and reconfigurability.
But at the same time, in both instances, I also UNDERSTAND why those changes were made. (And, contrary to the prevailing conspiracy theories of the nostalgia-blinded set, it has nothing to do with intentionally making things harder on the enduser.)
Modern cars achieve power and efficiency levels never dreamed possible in Henry Ford’s day. The same way that, if your smartphone were a modular system with external removable battery, it wouldn’t be a 6-8 oz supercomputing platform with integrated HD display and all-day battery life — plus, if it’s less than 5-6 years old, all housed in a SHOCKINGLY* water-resistant package. (At least until you, the user, break the factory seals by opening it up.)
— (I’m taking “survive a drop in the bathtub with no repercussions whatsoever” levels of water resistance. And to think we used to keep bags of rice around as emergency dessicant!)
It´s not because something got more complex (and performant) that it reaches beyond your comprehension capabilities that everybody else is stuck. If you don´t upgrade your knowledge, you´ll end up stuck.
Rice is a very poor dessicant.
“But at the same time, in both instances, I also UNDERSTAND why those changes were made. (And, contrary to the prevailing conspiracy theories of the nostalgia-blinded set, it has nothing to do with intentionally making things harder on the enduser.)”
And yet, we catch cell manufacturers utilizing software “updates” to retard phone performance, or glue in batteries that, by definition are “consumable” items, so as to force people who are otherwise happy with an older phone into perpetual subscription slavery.
You mention cars… bought my last pickup new. I ran it for 25 years until the transmission went out. I could have fixed it, but all the plastic stuff was dry-rotting and even things like connector shells were starting to disintegrate, so I decided I’d earned something new.
The new truck has some nice “modern” features, BUT… it cost twice as much, it will NEVER last as long or be as repairable as the old truck (because of the electronics and plastic) and how nice its tech gizmos are, it doesn’t do anything the last truck couldn’t do.
Is it newer? Yes. Is it better? Not sure.
I’ve been saying this for years. I love old cars for their looks and home repair ability. But new cars are better in safety[1] (yes I said it) and performance and efficiency and reliability[2] (yes I said it) and features and price[3] (yes I said it) and noise and comfort and on and on.
I sure do love that old style tho.
[1] IIHS crash-tested a heavy 1959 Chevy against a lighter 2009 Chevy. The dummy in the new car suffered a leg injury, the dummy in the old car was nearly decapitated.
[2] Old cars were clapped out at 100k miles. But I often start my search of new cars at 100k, for maximum value.
[3] Adjusted for inflation, old cars cost more than new ones.
The first electronics in cars were radios. Lee de Forest demonstrated a car radio in 1904. Chevrolet offered a factory-installed Westinghouse radio in 1922, a Philco radio in 1927. Motorola started producing the first widely popular U.S. radio in 1930. In the 1920s there were also developments in England and Australia.
Not counting the ignition spark system, of course.
Do points count as “electronics”?
My ’53 Willys Jeep had a voltage regulator like the one featured here, and not a single semiconductor in the whole vehicle. Not so much as a diode. The ignition was the usual points, coil and distributor. I would have said that vehicle had no electronics.
The ammeter was especially funny: it had just the high current batter cable running through the body of the ammeter. No shunt, no connections, just the cable passing through the meter: Essentially a clamp-on meter. The needle was moved by the magnetic field of the wire directly.
That truck lasted until ’77, but I wouldn’t say it was long-lived. It was held together by baling wire and Bondo near the end. It should have seen the junkyard a decade prior, but it still ran and it could still haul wood and trash and still plow snow, so had its use.
And that relay-based voltage regulator lasted until the very end.
Previously reported on: https://hackaday.com/2024/04/08/1950s-switching-power-supply-does-it-mechanically/
And again, this time automotive: https://hackaday.com/2016/07/04/retrotechtacular-dc-to-dc-conversion-by-vibrator/
Oh don’t be such a cumshot in a tub of yoghurt. At least new writers have it easier by just re-posting articles from a previous decade.
It would take a just a glance at what was posted to recognize it’s not remotely the same thing.
If you find this post interesting, may I suggest you look into the carbon pile regulators found in vintage aircraft?
This design starts with a stack of carbon disks, pressed together with a spring. The electrical resistance across the stack varies with pressure. Wired in series with a generator’s exciter (field), the output of the generator therefore varies as a function of the pressure in the carbon stack.
Now you add a solenoid, mechanically linked to the stack in such a way that it tends to work against the action of the spring. This solenoid becomes the “sense” part of the regulator.
If the generator voltage is low, the solenoid is weak, the spring force dominates, the carbon pile is compressed, resistance goes down, and excitation to the generator increases. The generator voltage will creep up, as a result.
If line voltage is high, the solenoid is strong and its force dominates the spring. The pressure on the carbon pile is relaxed, the resistance rises, causing the excitation to the generator to fall. The generator output voltage falls.
This serves the same basic function as the mechanical automotive regulator described in the OP, except that while the car version is a bang-bang type regulator, the carbon pile is a proportional regulator with much more civilized output. In fact, it doesn’t require the presence of a battery to “smooth” things out, and so it can be applied to AC output generators, as well.
Engineers created astonishing and elegant machinery long before it became possible to put a microcontroller into everything, (whether it needed it or not.)
Very cool. I had not heard of those types of regulators, despite flying in a plane that probably used one (late ’50s Cessna 150). Thanks for sharing.
Pile regulators are nice for the avionics but, the most reliable and simplist ignition system in aircraft is the magneto. No battery to worry about once the engine is started.
Another related, outdated classic tech would be the regulators for AC. Mechanically and magnetically controlled automatic tap switchers/autotransformers, saturation regulating transformers, and the like.
I was literally just looking into this last week, asking Gemini about EMP-hardening automobiles. Cool topic.
My first car, a 1959 Dodge, used this regulator. Expensive and crude, but easy to figure out. One could tweak the relay to adjust the current and voltage.