Boss DF-2, how to remove the footswitch

[Dimitree]

hello

in this pedal (my is a clone, not the original pedal) the footswitch is used for the bypass and also for the feedback function.

I'd like to add another footswitch only for the feedback function, so one is used for bypass (true bypass, already did) and the other for the feedback function.
Can anyone help me understand how to wire this new switch (either momentary or latching, still I haven't decided)

schematic:

[thehallofshields]

Are you going to re-house it?

I guess you could drill a momentary/non-latching switch into the battery compartment, so it would be like;

Light press: Feedback
Hard press: Bypass

[Dimitree]

As I said, mine is a clone so it is not a matter of where to put the switch. I will use two switches, but I need to understand how to wire them

[ElectricDruid]

If you've made it true bypass already, what modifications have you done to the schematic you posted?

The switching in that pedal is a complicated mess by the looks of it! What does it do when you step on the pedal? What's the standard action of the single Boss switch? I'm trying to get a grip on what does what.

Thanks,
Tom

[Dimitree]

I just wired a true bypass switch around the input and the output, the existing bypass circuitry is still there and unmodified. What I want is indeed remove the un necessary circuitry but keep the switch for the feedback function

[thehallofshields]

What's the standard action of the single Boss switch? I'm trying to get a grip on what does what.

This one is a little different.
Press and Release is Engage/Bypass. This will turn on the DS-1 like distortion circuit.
Press and Hold makes the PLL 'lock' the frequency coming from the fundamental detector, and the starts envelope generator.

The combined effect a frequency slowly swelling with distortion and a little vibrato, which sounds a bit like guitar amp feedback.

[Dimitree]

after a bit more of study of the circuit, I guess the only part necessary is the 8a switch (4066) and the signal that triggers the envelope generators.
The rest of 4066 is used to make the led blink at the LFO frequency.
is that right?

[slacker]

The easiest thing to do is probably to remove Q4 and replace Q5 with a jumper from source to drain. That will make the effect permanently on so you can use what ever true bypass wiring you want. A foot switch connected to "Foot SW" on the schematic will then control just the feedback effect.
Yeah it looks like 8c and 8d control the LED.

[Dimitree]

thank you,
what is the purpose of R78, R88, Q14? they are right below the NAND gate near the foot switch.
I understand that the NAND (used as inverter) togheter with R76, R77 and C58 form a debouncing circuit, but I don't understand why that other parts.

Also, is Q8 used to mute the feedback sound when you de-engage it?
if so, does it act as on/off gate, or as a sort of VCA (to slow fade out the feedback sound)?

[DiscoVlad]

thank you,
what is the purpose of R78, R88, Q14? they are right below the NAND gate near the foot switch.
I understand that the NAND (used as inverter) togheter with R76, R77 and C58 form a debouncing circuit, but I don't understand why that other parts.

Also, is Q8 used to mute the feedback sound when you de-engage it?
if so, does it act as on/off gate, or as a sort of VCA (to slow fade out the feedback sound)?

Q14 looks like it's used with the 4066 (and Q15) to toggle the state of the LED.

Being in a feedback loop with the inverter (9a) makes the output at the collector oscillate, and that gets mixed with the LFO to make the LED flash when the footswitch is held down. (I think, might be wrong here)

Q8, I guess so?
From the demo videos on youtube the feedback sound cuts off when you disengage the switch. so it's either silencing the PLL output, or letting it pass through to the output depending on he state of the switch

[duck_arse]

Q14 appears to be inverting the output of the nand gate, so the "8c" "8d" gates are one on/one off. when c is on, it allows the square wave to the base of that transistor, to do - whatever, but on/off/on/off, like. indicates the lfo rate?

[Dimitree]

thanks again
and what's the purpose of D8, R45 and C29 (they are connected to the control pin of 4066 '8a') ?

[duck_arse]

when that pin 12 goes high, the diode is backwards, the 470k(?) passes charge to the cap, so it rises slowly, turns on that gate late. when the pin 12 is low, the diode is forwards, so the cap will be discharged via the diode (no resistor to slow it) all the way over at Q14, which will be on. gate opens quick.

I think.

[Dimitree]

ok, if so, then is used to modulate the feedback with the LFO but after a little while, not as soon as you activate the feedback

[wordstep]

This is not a easy clone.
Each 4046 IC has different characters.

To taste the circuit, forget (remove) the IC8 (4066) , the flashing led and all the switching circuit.
Replace 8a with a push OFF button. If the circuit works,when you disconnect Pin9 and Pin13 of IC7 with the push button,
you can get a sound from R67/R68  (when you put 9V to  R72/R73 to turn on the Q11 & Q12)

Begin with that.