Working.
Handy for getting guitars and line level signals up to Eurorack level.
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At some point I’d like to add a piezo disc to the rear of the panel like the real Mikrophone.
As I understand it, all I’ll need to do is solder the the red wire on the piezo disc to the switch on the input socket, solder the black wire to ground, then glue the piezo to the panel’s back.
I’ve left plenty room under the circuit board. Anybody know if I’ll need to add a little square of copper to the back of the panel first as as shielding for the piezo?
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No need to add shielding. As long as you can attach it, it will amplify whatever is going on around it.
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Thanks. Hopefully the postie will deliver the piezo discs soon
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Or you can do what I did: Fail to find the piezos you bought several years ago, order new ones, receive new ones, lose new ones, find old ones, use old one, find new ones.
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Ha. I was sure I had one on the end pin of an acoustic guitar - couldn’t find it. Ordered some off ebay…
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I guess for piezo’s you don’t need the gain factor (max 5 * 26 according to the text in the diagram) the circuit provides, or do you?
That’s what’s in the original Music Thing Modular Mikrophonie design.
Nice! i think i have pretty much everything i need to make one of these minus a couple things… 50k pot and 56k res. Guess this goes on the list too now =P
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You can use a 100k pot no problem.
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You might want to sub 4.7k for the 2.2k resistors if you use a 100k pot, to keep the gain about the same. For the 56k you could probably use a 47k.
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That doesn’t answer my question.
It tells you who has the answer to it.
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Now all of that I do have! Thanks for the info and conversion =)
Ill gather the bits after I get the lfo finished tomorrow.
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Brill. Remember the track cuts - I forgot one first time round 
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Ive got most of the bits together and ready, just short the 100 C-cap and a socket for the TL072.
only thing is, what way do the schottkies go? which did you use? ive got 1N4001 and 1N4002
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See the stripboard layout, the grey stripe corresponds to the stripe on the diode. Either of your diodes should work — one with a smaller forward voltage such as a 1n5817 might be preferable in principle, but in practice it shouldn’t matter much. (They’re just there to protect against inputs outside the expected range, 1n4001/2 would block anything outside -1.1V to +13.1V, 1n5817 would go -0.45V to +12.45V. power reversal. 1n4001/2 will drop your ±12V rails to ±10.9V, which still should work. 1n5817 would drop them to ±11.55V.)
The 100 nF caps aren’t critical, you could leave them out for now or possibly forever. They’re to block high frequency noise at the IC.
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Ive got the two 1n4148 (d1,d2) its D3 and D4 i cant see the orientation of (i would assume they go outward from the 10 pin connecter, but not 100%)
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Gotcha, I got the diodes mixed up. See corrected response above. It’s the 1n4148s that protect the CV, the Schottkys protect against power reversal. D3 connects to +12V so you want the stripe away from the power connector — at the top. D4 connects to -12V, stripe goes on the side toward the power connector, also at the top. The diodes will drop your ±12V rails by the forward voltage, so to ±10.9V using 1n4001/2, or ±11.55V using 1n5817. Either should work okay. Or you could replace them with 10R resistors or even wire jumpers, just make sure you never apply power backwards.
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Awesome! My assumption was at least half right =D
I’m also using keyed 10 pin connecters where i can rather than headers (i dont trust myself to remember that red stripe is actually blue (-12v) on the cables haha.)
Thanks for the speedy responses, you’re legit a champ’ =)
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