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#152941 - 03/12/06 01:37 AM Vibrator Supplies??
Trumpy Offline

Member

Registered: 07/05/02
Posts: 8540
Loc: SI,New Zealand
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.
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#152942 - 03/12/06 05:54 AM Re: Vibrator Supplies??
winnie Offline
Member

Registered: 09/15/03
Posts: 652
Loc: boston, ma
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

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#152943 - 03/12/06 07:22 AM Re: Vibrator Supplies??
geoff in UK Offline
Member

Registered: 12/30/02
Posts: 172
Loc: UK
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.

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#152944 - 03/12/06 08:38 AM Re: Vibrator Supplies??
pauluk Offline
Member

Registered: 08/11/01
Posts: 7693
Loc: Norfolk, England
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.

 Quote:
to transform the 12VDC to 250V

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

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#152945 - 03/14/06 12:15 PM Re: Vibrator Supplies??
RODALCO Offline
Member

Registered: 12/08/05
Posts: 863
Loc: Titirangi, Akld, New Zealand
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.
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#152946 - 03/15/06 08:39 AM Re: Vibrator Supplies??
Electricmanscott Offline
Member

Registered: 01/12/02
Posts: 1478
Loc: Holden, MA USA

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#152947 - 03/15/06 03:41 PM Re: Vibrator Supplies??
Trumpy Offline

Member

Registered: 07/05/02
Posts: 8540
Loc: SI,New Zealand
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,
 Quote:
And don't forget that prior to the mid-1950s or thereabouts, most car electrical systems were 6 volts.

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?.
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#152948 - 03/16/06 05:02 AM Re: Vibrator Supplies??
pauluk Offline
Member

Registered: 08/11/01
Posts: 7693
Loc: Norfolk, England
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.

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#152949 - 03/16/06 08:23 AM Re: Vibrator Supplies??
SvenNYC Offline
Member

Registered: 08/19/02
Posts: 1685
Loc: New York City
 Quote:
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.


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.

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#152950 - 03/16/06 01:30 PM Re: Vibrator Supplies??
JoeTestingEngr Offline
Member

Registered: 11/04/05
Posts: 786
Loc: Chicago, Il.
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

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