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I need help selecting a high voltage relay Answered

I'm trying to build a circuit that will allow me to use one inverter to alternately light 2 CCFL tubes (a blacklight tube and a white tube) with a single microcontroller pin via a HV relay -- that is, if it is cost effective to do so. I'm hoping someone could help me figure out something.


I noticed that your inverter
is intended to run from a 12V supply, which led me to guess you might be intending to run everything from a 12V supply. 

I imagine a 12VDC supply.  It could be a sealed lead-acid battery.  It could be a wall wart, or an old computer power supply.  I also imagine that the microcontroller will be running on a small 5V supply, like the ubiquitous 7805 regulator, which draws power from the 12V supply.  Moreover I imagine 12-volt relays, at least one, that you want to switch on and off via the microcontroller and its 5V=high, 0V=low, outputs, that are likely very limited in the amount of current they can source or sink.    So I also imagine one small NPN transistor per relay, to help drive it.  It is all a lot to imagine, so that's why I drew a diagram of it.

I have not drawn the high voltage part of the circuit, because I have not decided what is the best way to do that part,  but I wanted to show you the usual trick for driving 12V relays with a 5V microprocessor with wimpy 5V (current limited) outputs.


Based on mousers prices and a general lack of info, I think 2 inverters and a 12v supply relay would be the most cost effective route. Thanks for the diagram, it'll help.

Check out the relays available at sparkfun.com. I know they have one there that is capable of switching mains voltage using logic level signal.

How high voltage? I'd switch at the 110V/220V level, which is easy, and just plug the two lamp sockets into that, rather than trying to switch the high voltage output of the CFL driver circuit.

Relays which can switch house current are widely available and cheap.