An old timey radio

I've never had a chance to do much experimenting with tubes and RF, and I never got to build a regenerative receiver as a kid, so I thought I'd take a break from messing with headphone amps and try to design one using 12 volt tubes:

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I think I may put a tap on the coil to switch between the AM broadcast band and the lower end of the SW band; I don't really want to get into using plug-in coil forms. The values of turns for the coil are to be determined when I decide what I'm going to use for the form. These low voltage tubes have a very aesthetically appealing heater glow, and are extremely cheap!

Reply to
Bitrex
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Hi Bitrex, You might be interested in looking at this forum,

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in particular the section under Homemade Receivers--- Tube Radios. Several regen threads there. Mikek

Reply to
amdx

Where do you buy those tubes? A guy on Ebay wants 15 bucks for a 12AL8, not exactly cheap.

Over 6W for the 12AL8 filament alone won't get you an energy start rating on the radio :-)

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Reply to
Joerg

12V Plate supply hardly qualifies as "An old timey radio"

I can remember 90V BATTERIES ;-)

And I've owned several cars with vibrator generation of the plate supply. ...Jim Thompson

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| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
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Reply to
Jim Thompson

But I just remembered that my 1961 Renault Dauphine had an AM radio with 12V plate supply... made by Automatic Radio (Boston, MA)...

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...Jim Thompson

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| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
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Reply to
Jim Thompson

I have one of these radios:

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See? There were actually integrated circuits before you were born :-)

Oh yeah, those vibrator cartridges you had to replace once in a while.

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Reply to
Joerg

The schematic won't open. What's that transistor doing on its side?

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Reply to
Joerg

I never had to replace one. The nicest was in a 1950 Nash (I bought it in 1956). The radio was mounted in the trunk with a big woofer on the rear window deck. The vibrator supply used the field coil of the speaker as the power supply choke ;-) ...Jim Thompson

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| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
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Reply to
Jim Thompson

It's a PNG, but impossible to blow up to readable size.

That's the audio output device... 2N176... class-A :-) ...Jim Thompson

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| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
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Reply to
Jim Thompson

That car must have been a chick magnet back then :-)

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Regards, Joerg

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Reply to
Joerg

The front seats would fold back flat to make a bed ;-)

But that radio would kill battery in about an hour. I always parked on a downhill slope (*), so I could coast and pop the clutch ;-)

(*) Easy to do in WV (8-) ...Jim Thompson

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| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
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Reply to
Jim Thompson

Search for "subminiature tubes". Not exactly 12 volt tubes but most work with 40-60 volts.

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Reply to
asdf

They were pretty robust-- I remember wiring one up in series with the

120VAC outdoor Xmas lights- the strings of big 'C9' ones you could burn your hand on (7W per bulb), not the candy-a** ones you see nowadays. It created a beat frequency with the 60Hz mains so the brightness slowly varied.. no (then) expensive triacs or SCRs required.

Best regards, Spehro Pefhany

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Reply to
Spehro Pefhany

Yikes, what is that, an untuned RF amp and a regenerative detector?

That is very weird in several places.

John

Reply to
John Larkin

Sure, submins you can get. They must have opened lots of bunkers in Russia because things like nuvistors show up by the boxload on auction sites. But they won't be very good with a 12V plate voltage either.

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Reply to
Joerg

When I rented my first car in America (Chevy Nova, the small model) and the seat would not do that I asked the car rental guy. Because EU cars could nearly always do that back then. He said it was purposely not done, to discourage people from camping in their cars.

Most of the time I didn't even have a battery in my Citroen. It was either downhill or muscleing the crank. Thumb always _over_, else ...

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Reply to
Joerg

Guessing the filament needs current regulation. A 1.5V battery, fresh, might yield a short, bright flash instead. And with only 5 wires to it, I'm guessing these 'pentodes' are usually used the easy way out and wired up as triodes?

Jon

Reply to
Jon Kirwan

There were quite a few car radios using 12v ht around the crossover period from tubes to transistors. The ones i've seen (Motorola, Radiomobile ?) used transistors for the audio stages, but the performance was never as good as tubes with real ht. they were the last gasp of tubes in mobile equipment before the great wave drowned them all.

Fond memories of one or two valve trf sets with reaction control. Age

11, I used to get 120v batteries given at end of life for their application, but plenty for a one or two valve radio. They were huge, encased in pitch, built up from aa sized cells, with a brass tap socket at every 22.5 volts or thereabouts. Not very helpfull if you connected the ht to the filament, which I remember happening at least once :-)...

Regards,

Chris

Reply to
ChrisQ

They weren't cheap in the '60s or '70s, either.

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Reply to
Michael A. Terrell

Thirty-nine pounds? Wasn't that like a king's ransom in 1926? Like, equivalent to about three grand today? ;-)

Thanks, Rich

Reply to
Rich Grise

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