Dumb ?? on basic wiring

[gotbass]

got a rocker switch with led light inside, want to use it to control back light on my compass. Switch has 3 posts, number 1 and 2 are silver and number 3 is brass colored. I assume that number 3 is negative and would go to negative off battery. 1 and 2 would be hot and have battery positive to 1 and 2 to compass or vise versa. Am also wiring Eagle 250, but will wire it direct and not through switch. Your wisdom please. Thanks. Mike

[gotbass]

got a rocker switch with led light inside, want to use it to control back light on my compass. Switch has 3 posts, number 1 and 2 are silver and number 3 is brass colored. I assume that number 3 is negative and would go to negative off battery. 1 and 2 would be hot and have battery positive to 1 and 2 to compass or vise versa. Am also wiring Eagle 250, but will wire it direct and not through switch. Your wisdom please. Thanks. Mike

[Dsorgnzd]

Get yourself a multimeter and check the switch to see which terminal is connected to which other terminal at each switch position. Unless I misunderstood what you wrote, I seriously doubt that you would have both the positive and negative terminal of the battery connected to the same switch - doing so might give you the opportunity to create a short circuit, and that's never a good thing. If you have a single pole, double throw switch, then in one position the brass terminal may be connected to one of the silver ones, and in the other position, to the other one. If you don't know what a single pole, double throw switch is, then get somebody else to wire the circuit for you. And don't forget a fuse.

[aweiss44]

gotbass-there should be a sticker on teh switch, or a diagram on the box, showing which terminal is which. I THINK it's usually, positive line is cut and each end goes on teh outer terminals, then your ground goes in the middle term. BUT I will try and find a switch in the basement somehwere first to verify. P.S. migh thelp to just wire in a small bulb instead of the compass, so if you wire something wrong, you won't blow the compass up.

[mrsinbad]

OK, let me take a crack at this... First look at the switch to see if there are any marking for each terminal (like C for Common). If not, look for some wiring diagram on the side of the switch. Next, consider looking up the mfg site for the wiring diagram of the switch, assuming you have the mfg name and model number on the switch. That would be the easy answer.

Now, for some detective work. You will need a multi-meter for this. First try to locate the ohm (resistance setting) on the MM. Now, hook up one lead to #3 the brass colored (I'm guessing this is the common or (-) on the switch. Next, connect the other lead to #1. Look at the resistance measurement. If it reads out of range, good (meaning too high or no connection). Now flip the switch. If the resistance goes to 0, then you have just found the switch terminals. If this does nothing, then try connecting terminals #3 and #2 and do the same again. If the resistance goes to 0 or out of range (or vice versa), you have found the switch.

To test the positive or negative of the LED, you must set your MM to Diode testing. I would hook up the black lead to #3 (assuming it is the common (-) and touch either #1 or #2 looking to see if the LED lights up. If not, try hooking up the red wire to #3 and touch the other 2 terminals with the black lead. See if it lights up... If still not successful, you will need to try other combinations and do the above procedure. Now, if the LED glows brightly, it means it does not have anything to reduce the voltage from 12V. If you connect this directly to anything more than 3v, you will burn it out. So, you will need to get a resistor to reduce the voltage (subject of another post).

Give the above a try and let me know how you do.

[linstad]

If it is a lighted switch then it DOES need a ground. My guess is the brass is ground, the other 2 can be hooked up either way (power or load), it depends if you want the LED to light up with the switch "ON" or "OFF"

[snakehead]

Hello gotbass,
Post 1 goes to any unit you want to use.Post 2 goes to the red wire from your battery and post 3 is the negative of the battery.
Regards

[gotbass]

Snakehead - thank you. Had a friend over last night and his solution was the same as yours, works like a charm. Thanks also to all of you who have taken the time to help the electronically challanged. What a great forum. Yours in sport. Mike