220 to 110 to 24 volts DC

[Ron Marcus]

Good Morning!
Here's an interesting one. A client needs a PIR unit to be used on 110 or 220 volts. We have a 220 to 110 Triac converter (standard wall wart circuit) to lower the voltage to run the 110 volt lights. Here's the problem...The PIR unit itself uses a resistor and capacitor to lower the 110 volts to 24 volts to power the circuitry. When the unit operates on 110 volt mains, it works fine. When the 220 volt mains are used with the converter, the resistor heats quickly to popcorn making temperatures! It is a 560 ohm resistor and obviously is disipating peak voltage across it, instead of the 110 volt average.I'd prefer to not have another switch to double the resistance in series with the PIR. Is there another way?

[sayzer]

Hi Ron,

Did you check the table in the following post?

http://www.picbasic.co.uk/forum/showthread.php?t=3265

Post Number #26.

The table provides the values for correct Capacitor range both for 110V @60Hz and 220V @50Hz.


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