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Dumb electronics question (long)?

5/24/2000 1:43 PM
jon	Dumb electronics question (long)? So much to learn...... This one's got me stumped. I've got a few surplus lighted panel switches; I'd like to use one in a tube amp project. I guess it's neon, it's a push-on, push off unit where there's plus and minus markings at the base for the lamp. Between these contacts is a symbol -X- with the X inside a circle. Reads 42V, 1.2W. Looks like the manufacturer is Rafi 1.15108 (contacts rated 300V AC 4A SD). No problem with hooking up the switch contacts, the lamp's the problem. If I apply around 35-42V DC from a regulated power supply, works great. If I apply 35-42V AC from a variac, works great. I can use 120V AC thru a 5W 3.3K dropping resistor to get to around 38V AC or so, and she's good. (fried a few smaller wattage resistors.) This seemed kinda wasteful to me so I tried using a positive low voltage DC supply (like a bias-rail type setup) with a diode off one leg of the PT secondary thru a voltage divider with a big cap. No light, seems like the supply can't keep up with the amount of current draw the lamp wants (I had a similiar problem trying to feed 175V screens for 6AV5's a while back....solved that one with a second transformer) Sooo....is there a simple way around this,(am I overlooking the obvious) should I just use the big resistor with AC, or should I sh..can it and go out and get a rotten Radio Shack switch that I'll need to replace in a month? Thanx, Jon

5/24/2000 1:43 PM

jon

Dumb electronics question (long)?

So much to learn......

This one's got me stumped. I've got a few surplus lighted panel switches; I'd like to use one in a tube amp project. I guess it's neon, it's a push-on, push off unit where there's plus and minus markings at the base for the lamp. Between these contacts is a symbol -X- with the X inside a circle. Reads 42V, 1.2W. Looks like the manufacturer is Rafi 1.15108 (contacts rated 300V AC 4A SD). No problem with hooking up the switch contacts, the lamp's the problem.

If I apply around 35-42V DC from a regulated power supply, works great. If I apply 35-42V AC from a variac, works great. I can use 120V AC thru a 5W 3.3K dropping resistor to get to around 38V AC or so, and she's good. (fried a few smaller wattage resistors.) This seemed kinda wasteful to me so I tried using a positive low voltage DC supply (like a bias-rail type setup) with a diode off one leg of the PT secondary thru a voltage divider with a big cap. No light, seems like the supply can't keep up with the amount of current draw the lamp wants (I had a similiar problem trying to feed 175V screens for 6AV5's a while back....solved that one with a second transformer)

Sooo....is there a simple way around this,(am I overlooking the obvious) should I just use the big resistor with AC, or should I sh..can it and go out and get a rotten Radio Shack switch that I'll need to replace in a month?

Thanx, Jon

Replies:

ken gilbert jon,take the value ... -- 5/24/2000 2:12 PM