J.R.:
JQ> I have a halogen floor lamp in which the switch has melted and needs JQ> to be replaced. It's a 3-way rotary switch (off,low,high), but it JQ> only has 2 leads coming out (it looks like there was a resistor or JQ> something inside which was used for the "low" setting and was what JQ> melted). The only 3-way switches I've seen at the hardware store all JQ> have 3 leads. Is there a way to use one of these switches to replace JQ> mine, or am I stuck with replacing it with just a regular on-off JQ> switch?
I'm thinking the 'resistor' is a diode (rectifier) -- does it have a single coloured band at one and, or perhaps one end is bevelled? You can get replacements at many sources including Radio Shack. If your lamp is rated 300W (watts) you'll need to get a replaced rated 6A (amps); if the lamp is rated 150W get the 3A version (the 6A version will also work; using an over-rated device in this situation won't cause any harm). ...A common number for the device is the 1N4001 family -- I think the 1N4007 is the 6A version (it's been a while and I'm too lazy to check - these numbers will get you to the right section, narrow it down to the three or four items R/S sells, and the ratings are printed on the packaging).
You also need to get a double throw, center off switch. (Radio Shack sells these also.) Which ever one fits and has the appropriate ratings. IIRC they don't have 3A contacts so go with contacts rated
6A (again, overrating here won't cause problems).
Wiring:
Black Diode Line--------|