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How to wire switch?


NuEra
08-30-2002, 04:19 PM
This is a simple question, but what kind of switch do I need to wire a LED. I went to Radioshack and they had switches with 2 or 3 prongs in the back and different amp amount allowaces. What do I need? Its just a wire coming from power to the switch to the LED, and then grounded. I got this correct?

ci5ic
08-30-2002, 04:32 PM
All you need is a SPST (Single Pole, Single Throw) switch. If you're just wiring one LED, you only need a little one.

And your wiring is correct. Wire from + battery to switch lead. Wire from other switch lead to LED anode. Wire from LED cathode to ground...

However, you should put a current limiting resistor in the circuit somewhere. A 400 ohm (or thereabouts) 1/4 Watt resistor should do the trick.

93speed
08-30-2002, 04:43 PM
What kind of LED are we talking about? Windshield washer lights or just a regular radio shack plain LED? If you're wiring a specially made vehicle accessory, you probably won't need the resistor. If you have a plain LED, you will run into the use of a resistor.

NuEra
08-30-2002, 05:20 PM
its just a plain LED, I know it matters what side of the LED but what about the switch?, Does it matter which side the powers coming from? Should I put the resistor before the switch or the LED? thanks again

PaulD
08-30-2002, 06:11 PM
it's normal procedure to wire the switch between the battery and the LED .... to guard against shorts

ci5ic
08-30-2002, 06:32 PM
Switches do not have any polarity, so you can wire it up on either side. Shouldn't matter where you put the resistor as long as it's in series with the switch and the LED. No matter where it's at in the circuit, it's function will remain the same.

Personally, I would solder the resistor to the LED's anode (+). There's not polarity on resistors either. Then, run wires from the batt. to the switch, to the other lead of the resistor, and from the cathode (-) of the LED to ground.

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