Power a ceramic heat emitter on 12V?

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Old 08-17-09, 10:47 AM
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Red face Power a ceramic heat emitter on 12V?

Hello guys, thanks in advance for your time & help. Situation is: I have a 150W ceramic heat emitter that screws into a ceramic light bulb fixture. This means that it requires 120V, alternating current (AC), and 1.25 Amps (W = V x A). Can I power this heat emitter from a switching power supply that provides a maximum of 20 Amps on 12V (240W) in direct current (DC)? Basically, the wattage is supported, but the voltage and amperage are all different... I've read that AC or DC should not matter for incandescent light bulbs. Can I assume the same for this heat emitter? Thanks again!
 
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Old 08-17-09, 11:56 AM
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You can power it from a 12V source, however it will only output 1.5W of heat. The resistance (ohms) of the heating element is constant, so when you reduce the voltage by 10x, the power (watts) is reduced by 10 squared (100x).

To get the effect you want, you'll need to buy a heat emitter which is designed for use with 12V so it will have the proper resistance. Or you could just find a way to power it with 120V.
 
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Old 08-18-09, 05:15 AM
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Welcome to the forums.

Have you considered a power inverter? Inverters convert 12vdc to 120vac.
 
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Old 08-18-09, 07:58 AM
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Alright, thanks ibpooks! This explains things well. Ohms come in the equation as well...

The purpose was to power a few 5V fans from a PC switching power supply and I was wondering if I couldn't use the 12V rail to also power my heat source, but you clearly explains that I can't.

I'll just route power separately to the power supply and to the ceramic light fixture. Thank you very much for your time!
 
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Old 08-18-09, 08:00 AM
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Trying to do this as cheaply as possible... Won't need an inverter if I use power directly from household outlet. Thanks!
 
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