Guitar pedal modification - Page 1
Forum section: electronics / projects

author: Guitar760
author_rank: Newbie
timestamp: July 14, 2015, 01:44:06 pm
content: Hey guys, first time posting so I'll try to be good.I'm trying to modify a Mooer Pitch Shifter pedal to use a quiet SPST switch (or proximity switch but that's another tangent)It currently has a 3PDT switch that connects to a 6 pin header (two pins of the switch Aren't used and one pic is joined with another before the header.)I checked continuity on the switch - it seems that the pins are paired and each pair is NC - when the switch is depressed all connections are open. So it lifts the connection of each of the three pairs on header pins momentarily ( I'm assuming it activates a flip flop)So my knee jerk reaction was to throw in a 4 channel optocoupler and control all the channels with a single switch - the problem being, this is a true bypass switch so at least one of those pairs is running audio and I would be clipping half the waveform.So now I'm resorting to two DPST relays and I'm not sure if that will work.Does anyone know a good way I can emulate the existing switch?

author: John Coloccia
author_rank: Super Contributor
timestamp: July 14, 2015, 01:48:48 pm
content: What are you trying to do exactly? Are you getting a pop when you switch, or do you just not like the mechanical click from the switch? Do you have a schematic for the pedal? I don't know that particular one off the top of my head. Is it true bypass?Are you talking about the Pitch Box? I'd be surprised if there's any room in there to add anything at all.

author: Guitar760
author_rank: Newbie
timestamp: July 14, 2015, 02:02:23 pm
content: It's the mechanical click that's an issue. This is being used in a radio studio on a desk and activated by hand.I don't have a schematic, I'm just trying to emulate what the switch is doing. I'm pretty sure it's true bypass and it is the Pitch Box...and yes there's hardly any room.I attached pictures, one of which is my original idea that won't work

author: John Coloccia
author_rank: Super Contributor
timestamp: July 14, 2015, 02:45:00 pm
content: Well, pedals is something I happen to know something about... (look me up)My suggestion would be to just forget the idea. Spend a few bucks and buy or make a True Bypass looper pedal with soft touch switches. I think American Loopers makes one. There are probably others. If you don't care about True Bypass, you have even more options. You're going to have a hell of a time, and you'll make a big mess, adding the circuitry necessary to do the switching. That pedal is a true bypass pedal. If you want to use a soft switch, you need to add a good bit of circuitry to do it.

author: Guitar760
author_rank: Newbie
timestamp: July 15, 2015, 12:54:23 am
content: I'm opting for electronics - perhaps to my own detriment. I noticed after work that the switch is designed to make a connection between what I've labeled pins 1 and 5. I ordered some TLP222A-2 photo-mosfets and an omron relay - looking to hook things up so that a SPST flips the relay and powers the part of the photo mosfet that will connect 1-5, while opening the paired connections of 1-2, 3-4, and 5-6.If this looks like the workings of a misguided 30 year old child....yes...yes it is.

author: john_p_wi
author_rank: Regular Contributor
timestamp: July 15, 2015, 02:15:54 am
content: A lot of guys use H11F1 mosfet optocouplers in this position. Do a search on the pedal forums for H11F1 and noiseless....

author: RobertHolcombe
author_rank: Frequent Contributor
timestamp: July 15, 2015, 07:04:20 am
content: Can you leave the pedal footswitch engaged permanently and modify the power supply to have a soft switch, or is it running from a battery?

author: Guitar760
author_rank: Newbie
timestamp: July 24, 2015, 03:18:12 pm
content: Well...after building my first attempt and having limited success (I realized the 3PDT WAS toggle, not momentary) I've sketched out another circuit that uses a solid state relay and also adds a D-Type flip flop so I can use a momentary SPST as my switch. I also added a decoupling cap and a pull down resistor on the output...I think. Please feel free to recommend any other components I may need to add...I'm pretty new at this.