Author Topic: A/B for expression pedal  (Read 480 times)

phangtonpower

A/B for expression pedal
« on: October 04, 2020, 11:26:21 PM »
Hi, I was thinking of making an A/B switcher to use one expression pedal between two effect pedals. Easy enough. Maybe this one.



Instead of 2 LEDs I was thinking of using a bi-color LED. My confusion is how to wire the Bi-color LED. In the picture you take the ground from each LED and solder them to the outside lugs of the switch, but in a bi-color there is only one ground. Can anyone fix the diagram in how to wire the led? And what value for the resistor.
 

Thanks in Advance!

stallik

Re: A/B for expression pedal
« Reply #1 on: October 05, 2020, 12:04:46 AM »
Swap the negative led supply to the switch for positive and reverse the ledís. Same value resistor goes in the positive supply to the switch.

Sorry, canít draw it at the moment
Insanity: doing the same thing over and over again and expecting different results. Albert Einstein

phangtonpower

Re: A/B for expression pedal
« Reply #2 on: October 05, 2020, 12:33:59 AM »
Swap the negative led supply to the switch for positive and reverse the ledís. Same value resistor goes in the positive supply to the switch.

Sorry, canít draw it at the moment

Sorry I really don't know too much about electronics, I can follow a diagram like the one I posted, but I thought you can't reverse the polarity of LEDs?

What I'm picturing in my head from what you said is that the two outside anodes would be soldered onto the two outside lugs of the switch where ground would go, and the cathode then would go into the positive lug of the power jack with the resistor in series?

stallik

Re: A/B for expression pedal
« Reply #3 on: October 05, 2020, 03:29:07 AM »
Resistor can go either in the positive supply to the center terminal of the switch or in the negative return. The result is the same, choose whichever gives the most stable connection (resistors dangling in the air are unreliable) The negative return can be to any ground point, again choose the most stable. For resistor value, start with the recommended on your first drawing and adjust for taste. The lower the value, the brighter the LED.
Finally, watch for shorts on the LED legs. They're close together and a bit thin. A bit of insulation on the center leg is usually enough


Insanity: doing the same thing over and over again and expecting different results. Albert Einstein

alanbarton

Re: A/B for expression pedal
« Reply #4 on: December 16, 2020, 11:19:33 PM »
Resistor can go either in the positive supply to the center terminal of the switch or in the negative return. The result is the same, choose whichever gives the most stable connection (resistors dangling in the air are unreliable) The negative return can be to any ground point, again choose the most stable. For resistor value, start with the recommended on your first drawing and adjust for taste. The lower the value, the brighter the LED.
Finally, watch for shorts on the LED legs. They're close together and a bit thin. A bit of insulation on the center leg is usually enough



Thank you for that.

stallik

Re: A/B for expression pedal
« Reply #5 on: December 17, 2020, 02:01:07 AM »
Youíre welcome.
And, welcome to the forum
Insanity: doing the same thing over and over again and expecting different results. Albert Einstein