Popping sound when pedal is engaged

[DrAlx]

Baran, I have a solution for making the LED turn on/off while the center pin of the footswitch is permanently shorted to the bottom pin of the footswitch (ground), but it needs some extra parts.

I noticed that when the footswitch is toggled, the centre pin and the top pin of the footswitch always read the same voltage (either 0V or 3.9V).
But those two pins are NOT permanently shorted together.
I tried to measure the resistance between those 2 pins (when the effect is not in bypass, otherwise they are shorted) and I did not get a reading on my multimeter.  My multimeter can only measure up to 2 Mohm.  I don't see any other tracks leading to the footswitch, and I did not want to desolder it, so all I could guess is that there is some high value resistance between those 2 pins on the PCB and that it is larger than 2Mohm.

Now if you short out the centre pin to the bottom pin so that the effect is permanently on like you described in your last post, then the top pin of the footswitch is always going to be at 0V.  So you cannot use the voltage of that pin to set the state of the LED.
But I figured we ***might*** be able to use the fact that the resistance between the top and middle pins changes (from over 2Mohm to zero).

This put in my mind the Milennium Bypass as used in the Engineer's Thumb Compressor, where a change in resistance between the gate of a MOSFET and ground is used switch a LED on/off.  In the ET circuit, the LED is off when the resistance between the MOSFET gate and ground is less than 10k (the 10k is the resistance of the output pot in that circuit), and the LED is on when the resistance between the gate and ground is infinite (i.e. open circuit).
So I did an experiment using that Milennium Bypass but using the top pin of the footswitch to trigger the MOSFET.
And it worked !!!


First the schematic: Note I've drawn the footswitch connections to the input and output sockets on the wrong pins. They should be on the left and right pins of the middle row, not the top row.




After removing the old LED, I covered the holes with masking tape to avoid accidental shorts.



I wanted to keep the LED and holder but could not use the holes on the PCB, so I bent the legs flat and soldered wires to them, the idea being the assembly sits on top of the PCB.



Here's the bottom of the board as I have it now:



And the top:



I used masking tape to avoid accidental shorts.
I taped the wires to the LED to the sides of the footswitch to provide support to keep the LED in the enclosure hole.
Here it is screwed into the bottom half of the enclosure.



Is it worth all the effort?  Probably not.  I was happy with just the basic mod of shorting the input pins and adding 100k bleed resistor on effect output.
I only tried this for the challenge of seeing if it could be done without replacing the footswitch.

EDIT: After playing with the pedal a while I realised that it's better to have the pedal working the way it did before, with the reverb resetting when the effect is disengaged.  Having the reverb on the whole time in the background can be annoying as there is no way to reset the reverb apart from by changing the reverb type.  So I think I am going to remove the short between centre and bottom pins and have it work like before.  I will probably leave the reworked LED circuitry as it in case I change my mind in future.

EDIT 2:  Actually the reworked LED circuitry only works while the middle and bottom pins are shorted together, so I have decided to put things back as I had them before with just the fix for the switch-pop problem.

[Baran Ismen]

This

Baran, I have a solution for making the LED turn on/off while the center pin of the footswitch is permanently shorted to the bottom pin of the footswitch (ground), but it needs some extra parts.

I noticed that when the footswitch is toggled, the centre pin and the top pin of the footswitch always read the same voltage (either 0V or 3.9V).
But those two pins are NOT permanently shorted together.
I tried to measure the resistance between those 2 pins (when the effect is not in bypass, otherwise they are shorted) and I did not get a reading on my multimeter.  My multimeter can only measure up to 2 Mohm.  I don't see any other tracks leading to the footswitch, and I did not want to desolder it, so all I could guess is that there is some high value resistance between those 2 pins on the PCB and that it is larger than 2Mohm.

Now if you short out the centre pin to the bottom pin so that the effect is permanently on like you described in your last post, then the top pin of the footswitch is always going to be at 0V.  So you cannot use the voltage of that pin to set the state of the LED.
But I figured we ***might*** be able to use the fact that the resistance between the top and middle pins changes (from over 2Mohm to zero).

This put in my mind the Milennium Bypass as used in the Engineer's Thumb Compressor, where a change in resistance between the gate of a MOSFET and ground is used switch a LED on/off.  In the ET circuit, the LED is off when the resistance between the MOSFET gate and ground is less than 10k (the 10k is the resistance of the output pot in that circuit), and the LED is on when the resistance between the gate and ground is infinite (i.e. open circuit).
So I did an experiment using that Milennium Bypass but using the top pin of the footswitch to trigger the MOSFET.
And it worked !!!


First the schematic: Note I've drawn the footswitch connections to the input and output sockets on the wrong pins. They should be on the left and right pins of the middle row, not the top row.




After removing the old LED, I covered the holes with masking tape to avoid accidental shorts.



I wanted to keep the LED and holder but could not use the holes on the PCB, so I bent the legs flat and soldered wires to them, the idea being the assembly sits on top of the PCB.



Here's the bottom of the board as I have it now:



And the top:



I used masking tape to avoid accidental shorts.
I taped the wires to the LED to the sides of the footswitch to provide support to keep the LED in the enclosure hole.
Here it is screwed into the bottom half of the enclosure.



Is it worth all the effort?  Probably not.  I was happy with just the basic mod of shorting the input pins and adding 100k bleed resistor on effect output.
I only tried this for the challenge of seeing if it could be done without replacing the footswitch.

EDIT: After playing with the pedal a while I realised that it's better to have the pedal working the way it did before, with the reverb resetting when the effect is disengaged.  Having the reverb on the whole time in the background can be annoying as there is no way to reset the reverb apart from by changing the reverb type.  So I think I am going to remove the short between centre and bottom pins and have it work like before.  I will probably leave the reworked LED circuitry as it in case I change my mind in future.

EDIT 2:  Actually the reworked LED circuitry only works while the middle and bottom pins are shorted together, so I have decided to put things back as I had them before with just the fix for the switch-pop problem.

This is massive! I'll give this a try! You're a true legend, mate!

[euronymous0001]

Good day!

1) why nobody use higher resistor for the input and lower value on the output?
(e.g.1M - 220k, etc)

2) which is the better of the 3 combos: 2k2;22k ; or 220k?

Kinda got lost with the amount of info in the thread.

TIA

[Baran Ismen]

Good day!

1) why nobody use higher resistor for the input and lower value on the output?
(e.g.1M - 220k, etc)

2) which is the better of the 3 combos: 2k2;22k ; or 220k?

Kinda got lost with the amount of info in the thread.

TIA

Bigger amounts did not help in my case for some reason, i have begun trying with 1m and got lower.