indicator light for stand-by status?

[rp]

I got you on this one: you want to copy the Thomas Vox Cambridge Rev or Berkeley Super Rev light set up. Hoffman has the schematics, I've attached the detail. One problem is there is a very special bulb involved, iirc the other is just a #47 but I could be wrong and it's 2 special bulbs.

Here's an explanation I found off google, w/ thanks to the orig poster:

The second end of the "on" lamp does go to ground. The two lamps are wired in series, and each lamp has a different current draw. The theory is that when the two lamps are wired in series, the "on" lamp will light up brighter than the "standby" light. When the switch is set to standby, the "on" lamp is out of circuit, so the "standby" lamp lights up. Each of the two lamps is a different number... http://music-electronics-forum.com/t10123/

I once owned a BSR and had to buy a ten pack of the bulbs as they are so rare, I still have the pack and so know the #. But it's packed up and going overseas, it could be many months before I get around to unpacking that. I'll try and revive this post or post new someday. Maybe someone here knows or has a Thomas amp on hand and can post sooner. I also recall having the orig BOM on this amp so I know the Thomas BOMs are out there. Maybe a more intensive google effort will unearth it.

The Thomas Vox set up worked very nicely, with green and red jewels.

[rfgordon]

I worked on an old Teisco amp that had two pilots. One (white) came on for power up, then went off when flipped to standby, when a second, red one came on.

When I first rebuilt this amp a couple of years ago, I found a rotary switch that allowed the original functionality. Turns out it just wasn't mechanically tough enough, and it eventually fell apart.

So I replaced the rotary switch with the of-stby-play toggle. The white 120 VAC pilot was wired to the power circuit.

To get a red pilot (the white one has to stay on now) I used a red LED as the cathode resistor for the tremolo oscillator and put it in the original bezel on the face plate.

So now the red light comes on when the amp is switched off standby to play, and, as a cool bonus, the red light flashes in time with the tremolo when it's activated.

Red LEDs drop about 1.5 volts, so they can go in just about any cathode spot for 12AX7s.