switching a 120 v AC fixture with a vintage knife switch (low voltage?)

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Old 04-01-11, 04:31 PM
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switching a 120 v AC fixture with a vintage knife switch (low voltage?)

I need help with a project I am planning. I collect many things, among them, vintage electrical stuff. I have some old knife switches that I would like to use to turn on a standard 120 voltage lamp. Of course the knife switch has exposed contacts so I can't just use straight 120 volt power through it. I want the knife switch to be safe to the touch even with the lamp being powered on. I thought I could somehow use low voltage through the knife switch to power the 120 v lamp but I don't know what parts to use to accomplish this. I don't know any of the electriocal jargon that I read on some of the threads on this forum so I need a "for dummies" instruction. I am anxious to get going so I hope I can get some help here. Thanks in advance.
 
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Old 04-01-11, 04:36 PM
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Simplest is to use a 12v DC Edison base incandescent light bulb. It will fit in a standard lamp and can be run from a car battery. It will look like a 120v bulb but won't be.

The other way is to use a relay.
 
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Old 04-01-11, 04:42 PM
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Thanks for the speedy reply Ray. I already have a bulb which uses 120 volts. I plan to build a Steampunk lamp and bought some bulbs with funky filaments.

How could I build the switching mechanism with relays?
 
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Old 04-01-11, 05:15 PM
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You just need one relay. Common low voltages for relay coils are 5v, 12v, and 24v. 12v would be my choice bacuse it should be easy to find a wall wart that puts out that voltage.

The relay would need to be rated for 10a at 125 volts assuming you have no more then 15 60 watt lite bulbs.

The relay would need to be NO, normally open. It only needs to be single pole but if double ple you just wouldn't use 1 pole.

You would use the knife switch to turn t

P.S. Yes guys, I know that isn't a coil symbol but if you saw how bad my coil is you will know why I drew it as a resistor.
 

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Old 04-01-11, 06:30 PM
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Wow, thanks Ray. Is it safe to have the knife switch exposed and will it be safe to the touch when bulb is powered on?
 
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Old 04-01-11, 06:33 PM
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More safe then if you had higher voltage.
 
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Old 04-02-11, 04:11 PM
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Thanks again, it's a start.
 
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Old 04-07-11, 06:58 PM
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What is a "steampunk" lamp?
Andy
 
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Old 04-07-11, 07:09 PM
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Google images of Steampunk. It's an art form reflecting on industial/victorian/funky. When you see pictures of steampunk objects you will understand. I think it's pretty cool.
 
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