Magnetron Delay: Momentary Feedback Switch?

phi1

Active member
A couple options come to mind to get you started thinking. I haven't tried them myself. I sketched up quick schematics snippets.

Option 1:
Pros:
1. Soft touch SPST momentary switch
2. Simple mod to implement
Cons:
1. Feedback knob position affects oscillation amount
2. Delay Level could also be affected by the position of the Feedback knob
3. At low Feedback knob levels, the repeats could be shorted to ground entirely

Option 2:
Pros:
1. Oscillation amount is completely isolated from the Feedback knob
Cons:
1. DPDT momentary stomp switches usually feel clunkier than the SPST (at least the ones I've tried)
2. I'm not sure if there will be any click in the repeats sound when the switch is pressed


Admittedly neither of these solutions are perfectly elegant, so I assume there's a better way. (Maybe a more complex transistor switching arrangement). Option 1 should be easy to try out on your build with just alligator clips, Option 2 would require some more surgery. Keep looking around the net for PT2399 solutions like you already have been. Please report back if you find something or if you test out the above methods.
 

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Hi There, first of all sorry for the very late reply. Thanks for your answer. I did some research but unfortunately I wasn't able to finde useful information, but still want to do this mod ;) The one review for the pedal on the PedalPCB-Main site says "I added a havoc switch that sends the feedback into oscillation, which just made it perfect for my needs" so apparently there is an easy (!?) Way to do it :)
 

phi1

Active member
Jimi is describing (functionally) my option 1. He reversed pins 2&3 of the fdbk pot compared to mine, but in this case that doesn’t matter, since you’re just switching in the trimmer as a smaller resistor between pins 2&3.
 
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