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A small AC power source? Answered

I want something to power LEDs from (I want to stop fussing about the polarity), preferably cheap and compact (I've no intention of buying a lab power source to play with it once in a fortnight, and I don't have the money). I thought about mobile phone chargers, laptop chargers and model railway power sources (I own one of these), but they are all DC. Can you think of something?
PS Is it true that a motor connected to an AC source would stay still?



The right KIND of motor will run on AC AND DC. A PM DC motor will sit on the spot and buzz on AC.

Though LEDs WILL light on AC, the reverse bias voltage can destroy them, and wiring in anti-parallel would still mean you need to know which way round they are !


And who likes 60hz flicker? nobody likes that. :)

Well, actually I thought about playing around with that sort of ON/OFF indicator LEDs that are green in one polarity, red in another and should be yellow (!) in AC.

LEDs only conduct in one direction: they are DC
 A regular unsophisticated DC motor won't turn with AC.



7 years ago

No, just use a DC power supply. If you're that worried about polarity, then get a multimeter with a diode test function. With it, you can easily test polarity without blowing up the LED.