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using a RS wall wart for power

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MrDEB

Well-Known Member
going to etch some boards for my PWM LED candles and am worried or concerned about using a RS 273-1767 wall wart.
Should I add any caps or ?
Also is it better to turn the PIC "off" (LEDs off) using a phototranistor then when light hits the phototransistor the RB3 goes LOW as pictured
OR
take RB3 high on the presence of light thus turning off the LEDs
The pot R5 is adjusted so the LEDs just glow very softly.
Don't want full on bright or maybe I do.
Won't be able to tell until I get the board and leDs lit up.
the LEDs are surface mount from China so will measure current etc. before deciding on resistor values R2,3,4,6,7,10
any suggestions on the power supply or ??
 

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KMoffett

Well-Known Member
The RS 273-1757 should work fine. C3, placed close to the PIC's power pins, should be all you need. The voltage drop across R5 (dimming) will vary depending whether 1, 2, or 3 pairs of of LEDs are light at a given moment.

Ken
 
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MrDEB

Well-Known Member
Using a PWM prg.

the LEDs are lit most of the time anyway.
Just wanted to be able to adjust brightness if needed.
 
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