6V tube & vibrator car radio?

[MikeMl]

A friend has restored a 51 Chevy, and in the process, converted it to a 14V alternator system. He would like to run the original gas gauge, a 6V heater blower, and the original 6.3V tube/vibrator in-dash radio. All other appliances (lamps, etc) were replaced with 14V equivalents. I am going to build him an LM317 + Power transistor on a heat-sink 14V to 7V voltage reducer for the radio. The other things he will use a wire-wound power resistor.

Any body know how much current the original radio draws? My first car was a '48 Chev, and later I had a '52. Both had a vibrator-powered B+ supply, and 7 or 8 6.3V filament tubes, but I don't remember measuring the current? I'm guessing 5 to 8A.

 

[bychon]

I think it's less because I rebuilt a tube type car radio for a '56 T-bird and only used my 3 amp power supply.

 

[MRCecil]

You might try looking online for info on antique vibrator car radios or in your local library for the Sam's package for your radio of interest. There should be a model no. on it somewhere. I can't even remember who made those old Chevy radios...Muntz? I'm pretty sure it wasn't Philco...lol!

I just now typed into Google 1951 Chevrolet radio and got lots of hits including sources for service manuals with schematic. This link might be of interest to you. It's the service manual for three different 1951 Chevy radios all 6 tube with vibrator supply:

1951 Chevy Radio

 

[MikeMl]

Thanks, according to the reference posted my MRCecil, it draws 6.5A at 6V. The fuse is 14A.

 

[crutschow]

I had a '56 Chevy and I build a transistor multivibrator from a Popular Electronics article to replace the mechanical vibrator in the radio, which normally was not very reliable. Consisted of two power transistors in a push-pull configuration, a small audio transformer used to provide feedback, and a few resistors as I recall. Mounted it on a small rectangular piece of copper for a heat-sink, placed in the an old vibrator can after I removed the guts. Worked well and eliminated the noise from the mechanical vibrator.

 

[Reloadron]

Thanks, according to the reference posted my MRCecil, it draws 6.5A at 6V. The fuse is 14A.

I can see where that makes sense. When hot most of the tubes would draw about 300 mA and radios that used the 6V6 for the audio final drew 450 mA. Thus it was easy to get over 2 Amps just to heat the filaments of the tubes. That does not take in the vibrator or other power used.

More than once I remember my father screaming at me for running down the battery in the 56 Pontiac just because I liked listening to the radio.

Ron

 

[Boncuk]

Ts, ts , ts.

I really wonder!

So many pros on the site and nobody has the idea designing a boost SMPS for lousy 125 to 250VDC (required for car radio's valve anode voltage)?

If everything else fails return to the principle of "Wagnerscher Hammer".

Boncuk

 

[Nigel Goodwin]

Ts, ts , ts.

I really wonder!

So many pros on the site and nobody has the idea designing a boost SMPS for lousy 125 to 250VDC (required for car radio's valve anode voltage)?

If everything else fails return to the principle of "Wagnerscher Hammer".

Boncuk

You're rather missing the point about 'restoring' and not 'replacing' - though personally I would chuck the old radio out, and put a decent radio/CD in it's place

I threw out all the old vibrators we had in stock many years ago now, we used to repair old car radios at one time.

 

[Reloadron]

You're rather missing the point about 'restoring' and not 'replacing' - though personally I would chuck the old radio out, and put a decent radio/CD in it's place

I threw out all the old vibrators we had in stock many years ago now, we used to repair old car radios at one time.

Now see, that is where I have issues. To me if I am "restoring" a classic car I want it to be original and original is not a transistor circuit shoved in a vibrator can. Though difficult to find many of the old original equipment parts can still be found. I would have been the guy "dumpster diving" to retrieve those old vibrators.

Ron

 

[crutschow]

So many pros on the site and nobody has the idea designing a boost SMPS for lousy 125 to 250VDC (required for car radio's valve anode voltage)?

Substituting the transistors for the vibrator does just that. The transistors drive a transformer which generates the high voltage. That's an SMPS.

 

[MikeMl]

Here is a hack at it: Using an TL431, a large TO-220 NFET, and a power resistor. Note that the total dissipation is the red trace, split between the FET dissipation (dark blue), and the power resistor dissipation (green trace). The regulation is pretty good (light blue trace). The capacitor improves transient response because part of the load is the vibrator.

I know that a switcher would be way more efficient, but the car has a 60A (800W) alternator, so loosing 50W in the regulator is no big deal.

 

[Boncuk]

You're rather missing the point about 'restoring' and not 'replacing' - though personally I would chuck the old radio out, and put a decent radio/CD in it's place

I threw out all the old vibrators we had in stock many years ago now, we used to repair old car radios at one time.

Admitted, I missed the point.

You missed another one: Sell the vibrators to farmers for cattle fences.

 

[tcmtech]

I think the old Chevy's where lucky to have a 25 - 30 amp 6 volt generator at best. I have seen a few old vehicles with 15 -20 amp 6 volt generators more often than not.

So who wants to listen to a old buzzing tube radio that only picks up moderately powerful AM stations anyway?

I would rather have the windows down and listen to the old car itself!