Pilot LIght Question

[thebes]

I find that the pilot light on one of my tube amps is a bit bright when the lights are turned down low. This one is connected up from the 6.3v secondary heater tap.

I'm wondering if I could just use a different bulb to knock down the brightness? Most of these bulbs have numbers like 47. To go dimmer do I use say a 50 or drop to a 40? And does this cause problems in the power supply.

While I'm at it, how about LED's. I want to add one to a tube amp, hopefuly pruchased from Radio Shack. What should I be looking for that can handle the tube amp voltages as opposed to the small voltage requirements of typical low power SS gear, consumer electronics etc. Oh, and where would I hook it up? DC? AC?

[mikebse2a3]

I find that the pilot light on one of my tube amps is a bit bright when the lights are turned down low. This one is connected up from the 6.3v secondary heater tap.

I'm wondering if I could just use a different bulb to knock down the brightness? Most of these bulbs have numbers like 47. To go dimmer do I use say a 50 or drop to a 40? And does this cause problems in the power supply.

You could try some different resistor values (I know you have plenty to try[] ) in series with the bulb until you find the value that gave you the brightness you desire.

While I'm at it, how about LED's. I want to add one to a tube amp, hopefuly pruchased from Radio Shack. What should I be looking for that can handle the tube amp voltages as opposed to the small voltage requirements of typical low power SS gear, consumer electronics etc. Oh, and where would I hook it up? DC? AC?

What do you want the LED for (ie: just to light up when the amp is on or)? I believe you might check radio shack for some that already come setup to run of the AC line voltage if your just looking to light up when the amplifier is on.

mike tn

[Marvel]

An LED is a diode (duh!), so connecting to DC must be done the correct way. They have about a 1.2 volt drop across them. You need a resistor in series with them, as a current limiting device. You can put one on the 6.3 volt AC if you want, and put about a 300 ohm resistor in along with it. It will only be on half the time, since it is a diode. That also means it won't be as bright. Without the resistor, it won't come on. If you could keep upping the voltage, it would finally come on, but only long enough to explode. Don't ask how I know this...[*-)]

The caveat is that you may get noise in the amp from it constantly turning on and off. I put one on as a pilot lamp and couldn't hear any noise. They are really cheap, so it's easy to try. You don't need a high wattage resistor, either.

Bruce

[Arkytype]

There are three lamps which might float your boat: 1893, 1889 or 1816. These are rated to operate between 13-14 volts and might be dim enough.

OTOH, if your pilot light is behind a frosted or jeweled panel-mounted assembly, you might try using some theatrical lighting gel (or colored cellophane) between the lamp and panel.

Here's a link to a Mouser catalog page. Scroll down to the T-3 1/4 Miniature Bayonet Base Lamps to see your choices. Just click on any lamp to see the price.

http://www.mouser.com/catalog/637/103.pdf

Here's a link to an old GE lamp catalog that will no doubt provide hours of amusement.

http://www.stevenjohnson.com/ads/ge-ml-catalogo01.htm

Lee

[thebes]

Thanks guys. Mike, the LED would be used as interior lighting on that ultra secret project underway deep in the bowels of the Thebes Audiophile Laboratories. I may also try a light bulb in there, but also wanted to consider LED's.

Lee, great link to that GE light bulb sight. I've earmarked that one.