ECN Forum Forums Photo Discussion Forums Electrical Nostalgia Vibrator Supplies??

Sorry no pics guys, but I was talking to a fellow Ham Operator today and he mentioned that when Auto radios first came about, you had to have a device called a vibrator to transform the 12VDC to 250V(AC/DC?).
Please bear in mind these would have been Valve sets.
I know nothing about these devices, but they sound great from a voltage conversion stand point.
Can anyone shed any light on this topic?
Considering the actual transformation ratio, these could have been the first inverters?.
I'm really interested in the theory behind these devices.

A vibrator power supply was a _mechanical_ DC to DC converter, where low voltage DC was pulsed into the primary of a transformer using a set of vibrating contacts (like a mechanical buzzer) and then the higher voltage output of the transformer was rectified. I would not be surprised if there were similar mechanical devices with produced AC output at a fixed frequency.
http://www.siliconchip.com.au/cms/A_30708/article.html
http://www.siliconchip.com.au/cms/A_30674/article.html

I don't know any of the details of using vibrators. I just remember seeing mention of them in some old radio book when I was a kid.

-Jon

Now that brings back memories ! When I was still at school I was always keen to acquire peoples electro-mechanical junk to play around with and to dismantle to see how it worked.
A vibrator type car radio was amongst those, and I remember cutting off the vibrator can and fiddling for hours trying to get it to operate reliably. When it ran OK the radio, which used octal base valves, did work. It was in a large metal box intended to be fitted in the engine compartment and the two controls connected by mechanical flexible cables to a small control head. Goodness knows what car it was from!
A later generation of car radios I recall used "special" valves which would operate with 12 volt ht supply. I think these were the RF valves, and those sets had solid state audio stages. I discovered that near equivalent contemporary TV valves (intended for use at conventional ht) would still operate in these sets.

Vibrator supplies were very common for car radio equipment in tube/valve days. You need to apply some good filtering though to get rid of all the spiky waveforms and harmonics generated by the vibrating contacts.

These days, there are even specialist places selling solid-state replacements for those who like to keep their old radio running in a vintage/classic car.

And don't forget that prior to the mid-1950s or thereabouts, most car electrical systems were 6 volts.

I got a circuit somewhere in my archives for a reliable 12 Volts vibrator supply with 2 TIP 3055 transistor and 2 * 1 Watt resistors.

If I can find it I will post the details.

Thanks for your insight into this topic guys.
And Jon (winnie) thanks for the links.
Older electrical stuff really intrigues me.
I actually had one of the vibrator units in my possesion a few years back and I wanted to rip it open to see what was inside it, but I gave it to the radio museum instead.
I'm told that they came in 3 and 5(?) pin versions.
Paul,
Hmm, now that I didn't know, to slide slightly off-topic here, the currents in a 12V system with headlamps and the horn are quite large as they are, a 6V system must have had huge current draw, or were the lamps of a lower rating?.

The typical headlamps weren't quite so powerful as the bulbs found in many of today's cars, but then neither were the 12-volt bulbs which were common throughout the 1960s. 45W (high beam) and 40W (low beam) wasn't unusual.

It was to keep the currents down that the auto industry made the move to 12 volts. It was a time when cars were starting to get a lot more accessories: Extra lighting, rear window defoggers, heater blowers, etc.

Remember too that in the mid-1950s cars also had dynamos rather than alternators, so there was little or no charge until the engine was revved above idle speed.

These newfangled Halongen bulbs being used in modern cars are dangerous.

When you're walking or driving around at night and there's on-coming traffic, you get blinded when these things hit your eyes. It's like they're driving with their high-beams on at all times.

I can't believe the saftey regulatory bodies allow headlamps to be so bright.

Wonder if it would be possible to put a dimmer control in series with the lamps.

We also have to remember that compression ratios climbed in the 60's placing higher demands on starters. Also, V8s were becoming more popular.
Joe

During the 6-volt era, automotive engineers went to great lengths to avoid imposing loads on the system. My dad has informed me that windshield wipers used to be powered by manifold vacuum, and that when you accelerated to pass, your wipers would stop!

The early Volkswagens had an even more questionable power source for the wipers: the spare tire. There was an air line running from the trunk to the wipers. Better hope you don't have a flat during a rainstorm!

So many other accessories we take for granted now did not exist then, such as power windows. Water and fuel pumps were engine-driven. Air conditioning was also non-existent, except on the most expensive cars.

Also, remember that many pre-war cars had two headlamps and one taillamp, period. No turn signals.

Then, those of us who came of age in the '80s or later (myself included) might have a hard time imagining just how unreliable cars used to be. Before the advent of solid-state rectifiers in the early '60s, the charging system consisted of a DC generator with brushes which would burn out at the worst possible time. To have an early warning of this, you needed an ammeter on the dash, which carried the entire charging current. If the ammeter failed, it opened the circuit, and the car would grind to a halt.

I've also read someplace that the current practice of running the voltage regulator at about 14V dates from the '80s, when engineers were trying to find a way to accommodate ever-growing loads without an extremely expensive upgrade to a new battery voltage. I don't know what the charging voltage was before that.

I seem to recall reading around the turn of the millenium that within five years, all cars would have 42V electrical systems, with a DC/DC converter to supply lights, radio, etc. Anybody ever see one of these? Just imagine: electric A/C compressor! No more expensive refrigerant charges from leaky seals. You could have an electrically-driven camshaft, for infinitely-variable valve timing. I can't remember all the other advances that were supposed to result.

Is the future here yet?

All-Electric cars might do that, perhaps hybrids do. I have seen 8-cell lead acid batteries installed in customs

Talking 6 Volts systems.

In the Netherlands my mum had a Renault 4 with a 6 Volts generator and accumulator. ( 70Ah)
I rememberr quite well the Ammeter on the dash was which was a VDO -50_0_+50 Amp meter. I drove the car around our farmhouse in the weekend while I was about 14 Years young.
After starting, especially in winter at -15°C. The starter motor, (demarreur) turned over so slow that it ground to a halt before every compression stroke of the engine. After say like 10 seconds very slow cranking the engine jumped into life. Ammeter off the scale for about 2 minutes and feeling warm to the touch when the load settled down to 30 Amps and tapering off to about 10 Amps in 5 minutes.

Silicon Chip had a very interesting article re the 42 systems in the cars of the future.
July 2000 issue, probably still copies available from the editor. Worth while reading.
a 36 Volts battery system is proposed with a DC - DC converter to provide 12 Volts for lamps and low power devices while electrically steppermotor driven camshafts and electrically driven turbochargers can be run from the 36 Volts supply.
12 Volts is still preferred for lamps because the filament is thicker and will generally last longer with vibrations from the vehicle in motion than a 36 Volts lamp.

The problem was also adressed with high tech cars like BMW 750iL series which use a 12 Volts 150 Amps watercooled alternator. to furnish the high loads from elecrically heated catalic converters etc.

Interesting times ahead for future cars

I _think_ one of the two German upper class manufacturers (either BMW or Mercedes) already has cars with a 42V system, but I'm not sure.

6V always reminds me of the Trabant (yes, I read the Trabant BB a lot... )... they had 6V electrics until 1983! Made for very thick starter cables and frequent failures due to bad/high resistance connections. On the other hand... that car didn't _have_ anything electric! The windscreen cleaner was operated by a hand pump... you simply pulled the handle out of the dashboard...

The later models did have some funky features... the one I drove myself when I was about 14 had a "momentary fuel consumption indicator" - a flow meter in the fuel line from the tank to the carb with a set of LEDs that light up indicating the consumption.

As a sideline to this thread,
we were talking about this topic at a recent Ham club meeting and somebody mentioned that Valve (or Tube, depending on which side of the Atlantic you're on) technology is on it's way back.
Experimenters and Hobbyists, frustrated by the lack of new things in Kit building and the like are going back to basics.
Point to Point wiring is the norm and the use of newly manufactured valves are adding to the steady flow of people making thier own chassis'.
To a degree, Valve technology was a lot easier to repair as well, you didn't need a magnifying glass to identify components and the architecture of equipment was more "repairer-friendly", not the throw-away junk we have today.
All I can say is, it's about time.
So bring your 12AT7's and your 6L6's out of the cupboard!.
Some of us never stopped playing with valves.

Those new headlights which are very small with a very intense blue-ish beam are awful. I remember first seeing them on German cars in France some years ago, now they're becoming more common here as well. They might be great for seeing with, but as you say, they blind everybody else.


Vacuum-operated wipers were still being used on some British cars into the early 1960s, several years after the switch to 12-volt systems.

You bet! And that reminds me of a joke:

Famous last words #23408:

"Of course the top cap is the grid!"

I think vacuum-operated wipers are still used on buses.

I remember that the French always had traditional yellow lights in their cars up to mid, late 1980's.
Somehow that tradition has gone now. I was back in France in 1999 and most vehicles have now white lights instead of yellow.
If I could buy yellow headlight bulbs here in NZ I would fit them tomorrow.
I used them in The Netherlands in my cars I drove there and think they are great. The human eye is more sensitive to yellow anyway.
Also a lot easier in misty conditions too.
While travelling in Europe in "the old days" 9 out of 10 cars with yellow lights were French cars, as young kids on holidays we always counted them and looked at their numberplates

Yeah Ray,
These days kids need a Playstation in the back of a car to keep themselves amused.
Unreal eh?!.

Not only on their own cars, but they expected visitors to France to change their headlights to yellow as well! Along with the beam deflectors/masks for right-side driving, British car accessory shops used to sell small bottles of some kind of (cellulose?) paint for tourists to color their headlights yellow.

I think France finally had to conceded defeat and change to normal white headlights under one of the common European standards directives -- Maybe around 1992/93?

I know a young guy that makes tube guitar amplifiers.

And here's a guy who built a ***DIGITAL CLOCK*** with them....
http://www.eldocountry.com/projects/tubeclock.html

Wow! Now that is a project built for sheer love of doing it. I guess a lot of people would say "Why bother?" when you could just buy a quartz LCD clock module for less than $10, but that would miss the whole point of the exercise!

And I love Nixie tubes. I have an old Solartron digital meter with them sitting in a cupboard -- one of those projects I'm going to "get around to" eventually.

Nixie clock!! Too cool!!

Kind of like this homebrew computer keyboard.

I have a lot of projects, but I couldn't ever imagine having enough time on my hands for either of these!

"I think vacuum-operated wipers are still used on buses."

Generally, busses are diesel powered. diesel engines lack a throttle plate, and therefore have no manifold vacuum. to make up for this, they have a vacuum pump which is driven by the accessory belt. the vacuum pump is able to generate vacuum at any RPM, so if some buses do indeed use vacuum operated wipers, they should work just as good as their electric counterparts and not have the issue of not working when during acceleration like what happens vacuum operated accessories on a gas engine.

Not only were cars equipped with 6-volt systems, many, especially British cars, had positive grounds. I used to do car stereo installs, back when 8-tracks (and even 4-tracks) were king.

There were converters that could convert 6 volts to 12 volts, and even positive ground to negative ground. Some brave people got around this by isolating the stereo chassis from the car body metal.

The reason they switched to negative ground systems is that the ignition spark is more efficient than with a positive ground system, because the spark jumps the other way.

Yep, the positive-chassis survived into the 12-volt era of the early/mid-1960s on many British models. Remember this was still very much the age of the dynamo too; alternators didn't become common on cars until a few years later.


I knew a guy in a village where I lived once who changed his car about as often as other people change their socks! Every time he had problems with moving all his radio/tape/CB gear across, just on negative-chassis versions.

Then came the day that I opened the door to find him standing there with a CB set in his hand, the "aroma" of burned-out circuit-board tracks being obvious even without removing the covers. He'd just acquired an old early-1960s Ford Anglia and hadn't realized that it was positive ground. (Nor did he realize that a CB set doesn't need a 35A fuse inline!)


I think I did that with one transceiver. I ended up spending a lot of time playing with capacitors to get the live chassis at "RF ground."

In addition to vibrator supplies, another method of getting plate voltage for tubes in mobile applications was a device called a dynamotor.

Looked like a small electric motor, with no external shaft. Inside, it consisted of a low voltage DC motor and a high voltage DC generator on a common shaft. Almost as noisy as a vibrator supply electrically (and mechanically they sounded like a jet engine winding up !), but they did away with the need for rectifying the output voltage.

Some SSB ham transcievers (Heathkit and Collins for sure, probably others) of the late tube era had transistorized mobile power supplies available as options. A separate box that would convert 12VDC into 800VDC for the final tubes, as well as various bias voltages, etc.

That reminds me: If you're interested in this older stuff, keep a look out for the "Basic Electricity" and "Basic Electronics" series of books which were published by Van Valkenburgh, Nooger & Neville Inc. in the 1950s/60s.

They were written originally as instructional materials for the U.S. forces, and include operational descriptions of vibrators and dynamotors, as well as many other topics. There were editions re-written into "British Commonwealth" English and terminology as well, which may well have found their way to Australia and New Zealand. Public libraries might be able to get hold of them. Well worth a read.

I love tubes for amps. I have so bought so many non-functioning tube amps over the past 5 years. Most just had a bad capacitor, bad transformer (which I would usually replace with several transformers for the different voltages), or were just junk in the basement. I have an old Bogen challenger 60W PA amp I use for my bass. It uses 807's as the output stage tubes. It was $5, plus $10 to repair, and $30 for a speaker cab, and I spent $25 more for various parts to make it a 120W amplifier. It sounds a whole lot nicer than my $300 solid state amp head. I have also built some nice marshall clones, about $100 to build, sold all 5 of them for about $300 each.

The only bad thing is since I use solid state diodes for the power supply, I have to integrate a delay in it so the tubes don't get hit with power until the filaments warm up. I enjoy putting old-tech things to new uses. I have a cap/resistor meter with the old cat's eye tube (dont remember the tube number right off) that my grandfather gave me. It's pretty accurate.

I've never really found a solid state amp that I like. I only use them for vocal amps and PA amps for live gigs.

I just wish I had some original 12AX7s. The ones I have are Svetlana's, and they don't sound all that great. Used USA brand/European tubes usually sound better than new svetlanas.

You probably know this already, but keep a look out for an ECC83. That was the British/Mullard code for the 12AX7.

I still use a Vibrator transformer, most for fun, but I have an old electromechanical telephone exchange in working order. It has 2 set of vibrators for ringing current approx 25Hz 70V and a sound generator making a buzzing dial tone. In case of problems it has a reduendancy vibrator for each.

dsk

I haven't seen one of them since I played with car radios that had tubes in them. It was really just a Fred Flintstone switcher power supply.