# Magnetron Delay w/ Momentary Switch (demo vid)



## Danbieranowski (Aug 7, 2020)

Here’s a quick demo vid of the Magnetron Delay with an added momentary switch to make it oscillate (thanks @Mcknib). This was handled by putting a 20k trim pot into the feedback part of the circuit. When the momentary switch is pressed it overrides wherever the feedback knob is set to whatever the internal trim pot is set to, so if you max it it’ll self oscillate (you can hear that in the vid). 

This was a relatively difficult build for me because I had to stand up my resistors so they would fit on the board. I’ve never done that before so it was a little challenging to do for the first time. I also wired the LEDs backwards so I have to resolve that (easy fix). Otherwise, it’s a great sounding delay and a lot of fun to play with. No pics of the inside this time, but if I remember to I’ll upload them when I fix the LED wiring.


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## Cucurbitam0schata (Aug 7, 2020)

excellent vid, great description (holding out for gut shots! )

might have to make another magnetron if I get up the nerve. 

slick work, keep it up - appreciate your write ups


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## Jbanks (Aug 7, 2020)

Danbieranowski said:


> Here’s a quick demo vid of the Magnetron Delay with an added momentary switch to make it oscillate (thanks @Mcknib). This was handled by putting a 20k trim pot into the feedback part of the circuit. When the momentary switch is pressed it overrides wherever the feedback knob is set to whatever the internal trim pot is set to, so if you max it it’ll self oscillate (you can hear that in the vid).
> 
> This was a relatively difficult build for me because I had to stand up my resistors so they would fit on the board. I’ve never done that before so it was a little challenging to do for the first time. I also wired the LEDs backwards so I have to resolve that (easy fix). Otherwise, it’s a great sounding delay and a lot of fun to play with. No pics of the inside this time, but if I remember to I’ll upload them when I fix the LED wiring.


Would love to see how you wired the trim pot up to do the feedback. I have a little PCB that I can never get to work that is supposed to do that as a “secondary” function type button.


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## Danbieranowski (Aug 7, 2020)

Jbanks said:


> Would love to see how you wired the trim pot up to do the feedback. I have a little PCB that I can never get to work that is supposed to do that as a “secondary” function type button.


You can see more of how it’s done here: https://forum.pedalpcb.com/threads/magnetron-delay-momentary-feedback-switch.855/

You’ll see pictures from @jjjimi84 and @Mcknib that explained it more in full. That should help!


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## Danbieranowski (Aug 7, 2020)

Jbanks said:


> Would love to see how you wired the trim pot up to do the feedback. I have a little PCB that I can never get to work that is supposed to do that as a “secondary” function type button.


Here’s a messy photo of the insides. As stated the LEDs are wired backwards.

The yellow wire from the momentary switch is soldered to the middle leg of the feedback pot (leg 2). The middle leg of the trim pot is soldered to leg 3. Either of the outer legs of the trim pot gets wired back to the momentary switch. I’d reference the photo and the previous linked post for more detail as I was really just following their instructions and I used alligator clips to start with and test.


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## Danbieranowski (Aug 7, 2020)

Cucurbitam0schata said:


> excellent vid, great description (holding out for gut shots! )
> 
> might have to make another magnetron if I get up the nerve.
> 
> slick work, keep it up - appreciate your write ups


Posted a gut shot in the thread.


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## Danbieranowski (Aug 7, 2020)

Here’s more demonstrations of the sustain functionality (also fixed the LEDs).


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## Many__Of__Horror (Aug 7, 2020)

In regards to the resisitors standing up. Looks like this board uses 1/8W resisitors. Should usually state it in the BOM


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## Danbieranowski (Aug 7, 2020)

Many__Of__Horror said:


> In regards to the resisitors standing up. Looks like this board uses 1/8W resisitors. Should usually state it in the BOM


I just double checked and you’re right. #detailfail


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## Danbieranowski (Aug 9, 2020)

Nicer quality demo using my head’s emulated out into an irig into my iPhone. Works great if any of you are looking for a lazy way to capture nicer audio using your phone. I just plug it in and pull up my video app and record a standard video and it pulls the audio from the line in.


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