I got ahold of a few NOS 12au7 real cheap, that were manufactured for GM in the "AUTRONIC EYE" auto headlight dimming circuits.
I doubt that they are stellar for audio, but I couldn't pass up the price. Does anyone know who made them or what flavor of 12au7 they really are? They have a strange little flange toward the bottom of the glass.
I doubt that they are stellar for audio, but I couldn't pass up the price. Does anyone know who made them or what flavor of 12au7 they really are? They have a strange little flange toward the bottom of the glass.
aletheian said:
Picture Would Be Nice, I have GM/Delco 12AU7's here also, But they were a mixed batch of both GE & RCA's. I think It was a source price/supply thing like lots of companies.
Honestly, I am Finding some of those old GE long plates to be especially nice sounding. My Seymour Duncan 100W convertable amp loves them as phase inverters.
Trout
SHiFTY said:
There's really nothing to it. If this is typical, a photocell trips the
12AU7 which in turn trips the headlight-dimmer relay. 12AU7's can
power relays (they do so in Leslie speakers).
The only real headache here is that the power supply in something
this old would've used an electrical device called a "vibrator"
(no, not that kind of vibrator! Although I suppose you could
use one that way...It's about the right girth) to convert 12 or 6VDC
to the plate voltage. These devices were a nuisance and had to be
frequently replaced.
If this was an AC circuit the relay voltage would have been switched
by a thyratron tube like a 2D21 or 2050, eg, like a photoelectric
door-closer interruptor circuit on an elevator or garage door.
That's a Tungsol tube, the EIA code for Tungsol (322) is visible
on the tube. That's one nice 12AU7 you got there.
Tungsol also made auto headlamps and turn-signal flashers,
so it makes sense that auto-parts companies might buy
tubes from them as well.
funky flared 'AU7
My god it sure is!
I've got 5 RCA long plate 12AU7A's w/side getters! And I'm keeping them for something...
I've got some oldies but goodies tubes but I need a good digital camera with optical zoom so I can get some good close-up shots, to share with you guys. I'm thinking of my own web-site to share my diy audio and stuff so I won't clog up the forum. So wife if you're reading this (she occasionally does, aren't I lucky or what?) camera, camera!
Cheers you guys
Wayne
My god it sure is!
I've got 5 RCA long plate 12AU7A's w/side getters! And I'm keeping them for something...
I've got some oldies but goodies tubes but I need a good digital camera with optical zoom so I can get some good close-up shots, to share with you guys. I'm thinking of my own web-site to share my diy audio and stuff so I won't clog up the forum. So wife if you're reading this (she occasionally does, aren't I lucky or what?) camera, camera!
Cheers you guys
Wayne
Aletheian,
I think it's safe to say that those TungSol 'U7s will either make or play music.
Ned mentioned the vibrators in automotive tube electronics. Those NASTY things along with 0Z4 rectifiers went into the B+ circuitry. They were definitely UNRELIABLE. An early good use for SS was to replace the vibrators as the means of generating the low voltage AC that was stepped up.
If you build the headlight dimmer, use something nasty sounding and perhaps a charge pump for the B+.
I think it's safe to say that those TungSol 'U7s will either make or play music.
Ned mentioned the vibrators in automotive tube electronics. Those NASTY things along with 0Z4 rectifiers went into the B+ circuitry. They were definitely UNRELIABLE. An early good use for SS was to replace the vibrators as the means of generating the low voltage AC that was stepped up.
If you build the headlight dimmer, use something nasty sounding and perhaps a charge pump for the B+.
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