hey, I have build the handclap part of this link.
This is the simplest diagram I could find on the internet
The sound is really satisfactory for such this simple circuit. I think that the result is sufficient for my drum machine.
It is even better with a slight reverb on ass !!
try it and have fun !
here just a little extract (bad quality):
Nice one! The 909 board I’ve been working on has full a/d envelopes rather than little gates, but I think yours sounds great too. Did you make any mods to make it use eurorack power, or did you build it as is? Might also be nice with a switched/jack for external noise sources, to see what other sounds could be made by putting other stuff through it.
If I’m not mistaken, there is only a white noise input jack (“WN”), and not an internally one, so you can try others source 
A cleaner link: https://synthr.fr/wp-content/uploads/2020/03/Modular-Mini-Drums-schema-B.pdf
It connects directly to an internal white noise, excuse me, white noĂŻse, circuit:
thank you !
guys, It is a really nice idea to add an external noise input !! I never thought about it but it could indeed be super fun for a lot of Drums modules ! 
yes I built it as is for use with a + -12v power supply
I also used the lm339 like on the schematic using as a trigger conditioner
(look at “HC trig part” in schematic);
if you want to use a “gate to trigger” circuit with a classical opamp, you must to search the good values for an adequate time triggering…
I too amplify the output signal with replacing R509 (10k) with a 100k resistor. (gain x10)
Maybe more later, I would to post sound-extracts from the final module, directly recorded from my sound-card
I just found which site the schematic comes from…
https://synthr.fr/faites-le-vous-meme/modules/
OMG 
this page look fu**ing so good !!
Yes sorry I had not looked at the rest of the pdf, I thought there was only the part posted above 
If you changed R502 to a variable resistor, would that give you control over the clap space timing?
wow I suppose but I’m not sure, I will take time to test it later,
good idea man !! 
Hi! I’ve tried assembling the handclap setup, but I can’t seem to get a proper sound output. The 40106 seems to oscillate on its own without even needing the trigger. I’m probably missing something in the schematic. For instance, I don’t understand the Handclap input in sheet 2. Could you help clarify that for me?
Welcome @Hugo_o!
Take a search on the forum for tips on diagnosing issues with your modules.
A 40106 is pretty forgiving, as long as any unused pins are wired to ground or +ve.
Im not sure which schematic you are working from, the HC link you highlighted must have a counterpart elsewhere on the schematic.
At this point I’ll wave at the rest of the forum to jump in.
… Any moment now…
Schematic is linked above.
HC is a handclap trigger from a drum sequencer. Handclap can be triggered with that, or with the push button SW304, or with a signal coming in to jack J304. Vswitch is +15 V through a 1k resistor, but probably the HC trigger or the signal at the jack will be lower voltage than that so might not be critical. C307 and R322 shorten the trigger to something like a millisecond so the width of the input trigger shouldn’t matter. After the trigger shortener is a comparator with a threshold around 1.5 V so that’s what is needed going into pin 9.
None of which seems relevant to the 40106 self oscillating.
Thanks Rich, would you ground the unconnected pins?
Thank you for your response. Indeed, right after posting, I understood the benefit of the HC trigger. This is the second time I’ve restarted the setup on my breadboard and I can’t seem to get it to work. I must be making a mistake somewhere. I’m having difficulty understanding why, in the case of the metallic noise, the 40106 oscillates on its own and not in the hand clap circuit (highlighted here in yellow). If someone could shed some light on this, I would greatly appreciate it!
I don’t think that the circuit that you circled is the one producing the handclap sound. What you circled is part of, I assume, a trigger circuit that triggers the handclap (or something like that). The actual handclap is made by white noise produced by the transistor and filtered by the T filter of that op amp that follows the transistor (shown in the schematic posted by @BlackDeath above).
