I some old wall warts . When y test with a multi meter a 12 volt puts out 15 volts. I also have a computer supply with a listed output of 30 volts comes up at 39 volts. Are any of these usable for low voltage leds for street lights or building lights? Thanks tstark
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Those are unregulated supplies. I would only recommend regulated supplies so you don't have to worry about balancing the load.
You could put about 3 LEDs in series with a 270 resistor with the 12/15 volt wart, and see how the brightness suits you. Then put several of those strings in parallel. Just give it a try.
You could use the wall warts to power these DC-DC Adjustable Voltage Output Regulated Buck Converters with LED Displays.
@Gary P posted:You could use the wall warts to power these DC-DC Adjustable Voltage Output Regulated Buck Converters with LED Displays.
One needs to take care with some of those "regulators" as their output voltage can still fluctuate with the input voltage. The reviews for that specific one indicate that this is the case.
LEDs are current devices. Most common ones can handle up to 20ma. You can use any DC supply if you calculate what resistor will limit current to 20 ma, preferably a bit less than 20 like 16ma. Example using a 15v supply would require a 750 ohm resistor for 20ma.
Pete
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