homemade dimmer switch?

Greetings, This question has probably been asked and answered already but I cannot locate it. Here goes.. I own an RV. It has 12 volt lights located all around inside of the living space. The ones in the bedroom are too bright. How do I make a homemade 12 volt dimmer switch?? I have heard some talk of a potentiometer or maybe just splicing in an automobile dimmer switch. I was thinking about hooking up a 3 or 4 pole switch with a different resistor going to two of the legs. I have a bunch of resistor lying around but I am not sure if I am on the right track (e.g. will I burn something up)....any ideas..

It would all depend on the current. As you add resistance your changing the current and voltage. A 6 watt bulb at 12v needs 0.5amps, e/i=r says 6ohms. If you add 6ohms to the 6ohms, then the 12ohm total changes it to 1 amp and the circuit has 12 watts. I believe the resistor would do 6 watts of work. It's been a while since I've learned this, but at my figure you would need a good resistor to not burn up.

Yep, I multiplied the 1/2 instead of divided like I should have. I guess I can't reload ammo and do Ohms at the same time.

twentybelow wrote: Greetings, This question has probably been asked and answered already but I cannot locate it. Here goes.. I own an RV. It has 12 volt lights located all around inside of the living space. The ones in the bedroom are too bright. How do I make a homemade 12 volt dimmer switch?? I have heard some talk of a potentiometer or maybe just splicing in an automobile dimmer switch. I was thinking about hooking up a 3 or 4 pole switch with a different resistor going to two of the legs. I have a bunch of resistor lying around but I am not sure if I am on the right track (e.g. will I burn something up)....any ideas..

CARQUEST part number HS-92 is all you need.

A better solution which should also work on 12V fluoros is a PWM (pulse width modulated) circuit driving a FET or transistor. See "Silicon Chip" Nov 2008 pp30-34 "12V Speed Controller OR 12V Lamp Dimmer" (for 5A motors or 50W lighting). (siliconchip.com.au) I am building a similar circuit but tuned for 400Hz and driving the MTP3055 FET direct.