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More fun with LEDs..


Stalefish
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I'm cooking up a new circuit and I realised that I've got a 2 pole switch, of which only 1 pole is being used.. Sooo, with the recent interest in LEDs, I was thinking of using the remaining pole as an on off switch for an LED.. That should make it function as an on/off indicator..

Question: Quite straight forward, really.. Can I just put an LED directly in series with the switch and a 9v battery or is a 9v too much? Also, do I need a resistor somewhere?

Thanks!! :D

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Yes, you really need a series current limiting resistor to run an LED from a 9 volt battery - either check out one of the online calculators (here's one) and calculate for 15 mA or so, or just do what I do and use a 560 ohm for reds and yellows or a 390 ohm for blues and whites. :D

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