Hello everyone !
Since I have some free times this weeks, it’s time to finish a lot of ongoing project …
I need a kind of “slicer pedal” to get a very harsh tremolo effect on my guitar (like a square LFO driving the tremolo). But I really need it to be super sync with all my gears.
I already achieved it by building it with a DSP (an electro smith daisy). When it receives a MIDI signal with the note on 60, signal is open. When this note is off, signal is off. This is really simple.
But using a full DSP for this kind of FX sounds a bit too much for me. So I looked for a super simple VCA to drive with an arduino nano.
This is a bit dirty, but it works. When the arduino send 5V signal from its pin, signal is cut. I will just have to program to Nano and add the MIDI stuff to get it ready.
So my question is about this simple circuit with a transistor (BC547), and the RC filter (10k + 470nF) … What do you think? How could it be improved to sounds maybe better?
My electronic skills right now is just putting things together
The RC Filter is here to get rid of “clicks” sounds when the state at the transistor base change!
Thank you for your help !
I will share the final schematic & code when everything will be ready.
Are you interested in an On/Off situation only? If so, using an analog switch IC will give you much better sound quality. If you use a CD4066, DG442 or similar and control that using PWM you can even make the analog switch attenuate the signal. I did an experiment a while ago which worked quite well using PWM. You can find is described and demo-ed here: PWM fader experiment
Oh ! that’s really interesting !
I didn’t know about those chips !
Yes, what I need is a basic ON/OFF, so it might do the job.
I noticed there are some CD4066 on musikding.de ! I will order some and run the test.
Before you do, have a look at the DG442 and other DG configurations. They are more versatile because they allow negative input voltages (you can bias the CD4066 to accomplish the same) and a larger power range. But all depends on what you need and how muh you want to spend on them.
I have found that the negative part of a signal is distorted if the CD4066 has only a positive power supply. This is contrary to what I understand the datasheet suggests. In my designs therefore I used an opamp to bias the signal (lift it above GND level), send it through the CD4066 and then ‘unbias’ the signal again (lower it to be around GND level). I have loads of CD4066s, that’s why I used them, a DG442 would have made things more simple I believe.
Have a look here for my eurorack analog switch:
Oh okay I understand now …
Yes this could be an issue but I don’t want to sound it perfect cause everything goes in loads of FXs after that …
I might give a try with the CD4066
I rework a bit my schematic with the transistor and here is a new version who sounds less clicky
Just using my ears, not any electronic skills.
This is used in a MultiFX pedal send loop and it works as expected. Sounds not good with clean sound but I will always use it with distortion
