Dual LEDs wired to both be on or both be off.

Started by coffee-sipper, September 09, 2004, 10:40:21 AM

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coffee-sipper

I know this is simple but I can't think of another way to do this.  Would this work or do I need to seperte the LEDs.  This is for pure fun and there really isn't any practical reason for 2 LEDs on at once beyond cosmetic coolness - the LEDs will be part of a graphic printed on to the top of the pedal.  Do I want the LEDs in series instead? ie. resistor to -led+ to -led+ into sleeve of the input (I think this is what I'd try first).  I think I would probably use a 1 or 2K resistor to cut down on power drain as well.

Thanks,
Charles

Noisician for hire.

Fp-www.Tonepad.com

That's the way to do it.

If you have LEDs in parallel they will draw the same current, so rise the resistor to 2.2k (if you're using high brigthness LEDs, rise it to around 4.7k).

If you wanted them in series you'd need to half the resistor value in order to let more current thru.

Go with what you've drawn, just use a 2k-4.7k resistor.

Fp
www.tonepad.com : Effect PCB Layout artwork classics and originals : www.tonepad.com

Paul Perry (Frostwave)

I think they should be in series, not parallel. Because, since the foward voltage of two leds can be different (even if they are both red!) then, the one with the lower voltage sucks most of the current when they are in parallel. There is even a name for this (at least for the same phenomenon with paralleled transistors) "current hogging".

zachary vex

paul's right.  use them in series or give each one its own limiting resistor to match brightness (and put the two res/led combos in parallel.)