is it possible to use bicolor led for clipping diodes?

Started by Moonshiner, August 27, 2017, 02:12:51 PM

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Moonshiner

I am making a distortion with the clipping diodes going to ground. I would like to use 2  red Blue bicolor diodes in the clipping section. I got the leds to work via switch off a 9v battery and a on on dpdt  up was both red down was both blue leds. When I put it in the circuit they didnt light up at all. Is this even possible if so how would I wire it up? i used common cathode on both. I am wondering if i should try  one common cathode and one common anode . Opinions ??? ThANK you


anotherjim

Data for those LED's please. What connections do they have? What Vf (Forward voltage)?

If they are 2 wire type - LEDs connected inverse parallel like this...

... then they should work. The Vf of one or both might be too high for the effect to light them enough to see, but that doesn't necessarily mean they have no effect.

Watch out for LED's that contain a current limit resistor (as the one drawn does). That can seriously limit the audible effect.


Moonshiner

the red is 1,8 forward voltage the blue is 2,8. I could try red green but not much of a difference

Moonshiner

I need to use 2 its also for the look of the pedal. these do not have a limiter .I have rgb and rg I have been using the red and blue leaving the green disconnected. I have common anode and common cathode as well. I bought several types for this experiment . THANK YOU

GGBB

Common cathode or common anode cannot be made to work as an anti-parallel pair of clipping diodes. Both terminals need to be discrete for each LED.

Note also that whether or not an LED lights up when used as a clipping diode has nothing to do with whether or not it is actually clipping the signal. It is current that determines the brightness not voltage, so often the current of the signal being clipped is too low to make the LED glow noticeably.
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Moonshiner

#6
yes I understand the current factor I made a honey bee  a long time ago and kept thinking I had an issue because the leds didnt light up but learned from it ha ha . . I can get red or blue to light up in this circuit I have plenty of current . I am Wanting to be able to use a 2   3 wire  bicolor for color choice and  have both be red or both be blue with one switch. Thanks to all. There has to be a way right ?

nocentelli

Quote from: kayceesqueeze on the back and never open it up again

GGBB

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amptramp

Remember, LED's operate very well as photodiodes so if you have them mounted where you can see them, check them out under fluorescent light.  The extra photocurrent may be modulated at line frequency for each LED and this can introduce hum.  Put them inside the case and understand that the reverse current increases with temperature.