GP-10 DIY Mod - Ctl3/Ctl4

Started by MrKleinCZ, February 14, 2016, 09:05:30 AM

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MrKleinCZ

Because I don't use footswitches on GP to change patches I'v look for some "usefull" usage of those two  footswitches... By looking on board I found that those two switches isn't in "matrix" but just connecting wire from mainboard to ground.. I just cut apropiate wires, add DPDT switch to be able to set it to normal function and attach 3,5mm jack... now those switches operate as "external" footswitch :-)
(I'll provide wiring diagram later)
Now by connecting new 3,5mm jack with CTL3/CTL4 input I can use "down"/"up" footswitches as CTL3/CTL4...


sixeight

Great mod. I have been thinking about it, but decided not to. At least not for now...

Do the switches not work the wrong way around? Switches to ctrl 3/4 should be normally closed.

with a resistor and a transistor you can reverse the working of a switch. I can post the schematic if you are interested...

MrKleinCZ

#2
Maybe I'll add an invertor to work "correctly" (Thank You for info about that). But I planing to use it with my "controller" as external footswitch to operate more versatily ;-)

But I'll add this little logic to be compatabille with other devices...

whippinpost91850

Cool 8), That is simular to what I did to my GR55 to use extrnal expression and control switch.

MrKleinCZ

#4
Here is schematics (with included convertor to work as "normally closed" switches as mentioned above) ....

... modified ... seems to need "external" power to drive transistors ....

gumbo

Well done!    ...and thank you!  +1

Cheers,
Peter
Read slower!!!   ....I'm typing as fast as I can...

whippinpost91850


MrKleinCZ

hmm  >:( but seem that it causes some problems ... inverter doesn't work allways corectly  :-\

sixeight

Quote from: MrKleinCZ on February 15, 2016, 10:31:48 AM
hmm  >:( but seem that it causes some problems ... inverter doesn't work allways corectly  :-\

Is the problem with low state or high state of the switch?

I have used a similar design with the GR30 when I had that unit. Never gave me any trouble. I think the resistor was 22k and the transistor a BC550. But it shouldn't make a whole lot of difference...

MrKleinCZ

problem is that ctl3 input have big internal impedance, so it goes to low state by ~8k load - it cannot feed NPN trasistor and ctl4 triger bellow 0,5V - and this is also problem for classic transistors  :(, both inputs are totally diferent.... I'll try FET to handle this  ???

or use it without "inverting" but it could be problem in some situation when state of controls are switched...



sixeight

Quoteboth inputs are totally diferent....

Interesting. It reveals a little about how Boss implemented the use of an expression pedal and switches on the same input.

MrKleinCZ

Yes, seem that one input is strong to drive EXP potentiometer....

But fortunatelly this works now!!! I just added one wire with power to feed transistors /its avaiable on same connector as buttons/ ... now the added jack works as standard open colector output...

I also added sketch of possible PCB to use when You wont wire it in nest  ;)

sixeight

Excellent. Great you got it sorted.