Madbean Zero Point Mini Modulation Daughterboard

[Sensei Tim]

Schematic:



layout



I extracted the modulation portion of the Zero Point Mini delay pedal from Madbean.  I really love the sound of this modulation!

The only part I'm not sure about is Vc in the schematic.  Do i need that 47R resistor between the 9V and Vc?

The switch can be:
SPST if you only want to turn the modulation on and off (I think the LED keeps flashing even if the modulation is turned off.
DPDT if you want to turn the LED off when the modulation is off (toggle or stomp (or 3PDT stomp and don't use one pole))

Pretty sure this should work. If I have time i'm going to give it a try this weekend.

[Sensei Tim]

Tag it as verified. ;)

I had to get some "close enough" parts for the 680k and 1M5 resistors
And used a 4558 op amp but it works really well.

[Sensei Tim]

i was playing around with this some more tonight:

replace the 470k resistor with a 500k trimmer or external pot and let the funky sounds commence!

one thing that i found but i'm not sure what's causing it:

there's an audible tick that you can head that changes speed with the daughterboard rate knob, but the tick is also there (and can have the speed changed) even when the modulation is disconnected from the circuit via the toggle switch.

could this be the pt2399 picking up the modulation clock frequency from the modulation daughterboard from wires running too close to the pt2399 or something else?

[Sensei Tim]

Issues fixed. Everything cool.

[KT]

what was your fix? For me, using a TL062 instead of TL072 or 4558 reduces LFO ticking.

[Sensei Tim]

For my case it was wire routing.  When the rate wires went too close to the main board I would hear ticking.