Electronic Drums: TwinT around CMOS inverter?

[PHOBoS]

soundust

I see that cheshire Spock has already given some logic answers. As for the diodes, if they aren't marked
you can just use some general purpose diodes (no zeners).

[soundust]

Thanks for your replies guys!

I was hoping to experiment with the circuits virtually before I start assembling them, but I reckon I will have to embrace the breadboard. wish I had a scope though..

[gasboss775]

I had another idea for a gate to trigger circuit here

[gasboss775]

I've been experimenting with that Elektor Drum circuit that YuSynth posted on: Wed Aug 27, 2008 11:57 pm

Have made some improvements.

1. Have increased the resonance of the twin T circuit which subsequently overdrives the amplification stage that follows. The resonance pot effectively determines the level of overdrive in the next stage.

2. Have created a second path for the impact part of the sound, the level of which can be adjusted by a pot

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[gasboss775]

Have made further improvements to the Elektor bass drum. I'd hoped to build a VCA with one of the 4069 gates, tried using a vactrol to make a variable gain amplifier with the 4069, but attack time was just a bit too slow. In the end I conceded and used the trusty Roland VCA with npn transistor and an opamp.

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[gabbagabi]

from the archive

edit
better scan quality in the attached pdf

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[gasboss775]

@g.gabba

4011 doesn't seem like the obvious choice. I wonder if there's any sonic difference when using a 4011 rather than an inverter like 4049 / 4069. Will probably try both and see if there is a difference.

What book did you get these from?

[gabbagabi]

hi gasboss775,
its was german book from the library about repairing elektronic instruments, think it was from "FRANZIS",

may the 4011 was more common (= cheaper) in the time the book was written ?

cheers
gabbagabi

[gasboss775]

This is the latest version of a Twin T / Vactrol based Bass Drum that I have developed with Muff Wiggler user PWM.

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[LFLab]

No more CMOS?

Must give that vactrol vca a try, I wonder about the response.

Edit: o wait, that vactrol influences the resonant frequency, interesting, sound samples?
Any who, great work!