electro-music.com -> Developers' Corner

battery powered mini-mini-minimalist op amp sample & hold

Adolf Christus — Thu, 23 May 2013 16:25:53 -0600

It's alive <3

It works. My very first hardware sample&hold. my reaction
when I got it working was very emotional.

sample&hold is my all-time favourite part of a synth,
cause it creates a very musical "controlled chaos"
from something si ...

Using very thin wire?

rogerlatur — Thu, 23 May 2013 12:18:45 -0600

I ordered the wrong wire at mouser and I have a question:
Is there a risk/disadvantage to use 30AWG wire for analog circuitry instead of 22 or 24? I mean is it too thin to wire pots, jacks, bananas... in term of conduction?
Can I wire also to a powe ...

How to add control voltage to a circuit?

analog_backlash — Thu, 23 May 2013 05:48:06 -0600

I've attached an old Elektor circuit diagram for a switched capacitor VCF. I haven't tried it out yet, so I'd be interested if anyone builds it. I also believe that Ken Stone's Bi-N-Tic Filter (CGS57) has switched capacitors in it.

Gary

Simple CV sequencer with external clock control

rogerlatur — Wed, 22 May 2013 12:15:07 -0600

Your 2 answers are very helpful!
Thank you very much. I will then check the "baby seq" schematics and adapt. Nice!

2k Tempco advice

rogerlatur — Wed, 22 May 2013 11:53:38 -0600

Check especially the 2nd link halfway down, it´s there!
54k:1k at 1% tolerance! :oops:
I see.
This page is very instructive, and I will check also the other links. Thank you very much!

9v single supply Simple LM741 Triangle LFO: CV possible??

Adolf Christus — Tue, 21 May 2013 15:33:50 -0600

updated schematic with 100u cap, 5k pot and 100R resistor in series to the pot

Voltage controlled counter or 1-to-8-multiplexer?

L´Andratté — Tue, 21 May 2013 02:12:34 -0600

Reminds me of the Doepfer A152 Addressed Switch, which I couldn´t do without... It uses some chips called DG408DJ which seems to be some kind of dedicated 8-stage multiplexer.
http://www.digchip.com/datasheets/parts/dg/parts_dg06.php
Quote from d ...

The Jerkster -

elmegil — Mon, 20 May 2013 21:47:17 -0600

nice...

Sallen Key vactrol filter values

Rolbista — Mon, 20 May 2013 13:32:38 -0600

yes, the schematic from your link is what I used, first I had a 100k in the place you mention, but after it didn't react much i soldered a 10k resistor in parallel to the 100k, still, the response didn't change. Maybe it's the LFO's fault? Or a faulty ...

CMOS synth etc problem with heterodyne mixed output-probably

new voodoo — Mon, 20 May 2013 09:18:08 -0600

So i came up with this synth and it works fine but I figured since I had enough pins in the 40106 ic I was using-why not double it up?
So I did and used Beavis Audio's Heterodyne mixer section to combine the output into one..but im getting this high- ...

How to Choose the right Capacitor

Adolf Christus — Mon, 20 May 2013 06:36:23 -0600

thanksalot.

the butler looks inviting.

Stereo delay / Vibrato

Paradigm X — Thu, 16 May 2013 07:00:58 -0600

Awesome as always.

Very excited.

cheers Ben

LM13700 VCA and other circuits

richardc64 — Mon, 13 May 2013 08:45:11 -0600

Forget that. Below is the VCA from "SynTom", a single-supply Percussion synth. The original supply was 12V. For 9V the resistors most likely to need adjusting are R32 and R33.

The signal input is reference to ground, and the low end of the output p ...

Most simple VCF on earth

elmegil — Fri, 10 May 2013 23:27:58 -0600

Well, both the LM324 and the LF444 made it quite a bit more aggressive, but the high end of the pot (past about 3 o'clock) breaks up and sounds like crap, and it still doesn't really self-oscillate in any manner that tracks the frequency knob.

Of c ...

Single Op Amp SAW VCO

Adolf Christus — Thu, 09 May 2013 17:09:54 -0600

Yaay! this is great. much better than the spice simulators for my purposes

worked on the falstad sim. :D But I should buffer it with an op amp
as you said to remove the dc offset.

breadboarded three of them a few days ago :D FAAT!

I would li ...

KORG Minipops 120 Easy Sync Out Mod

NoizeToyz — Wed, 24 Apr 2013 01:33:09 -0600

This is great - I've just got a Minipops 120 and it sounds incredible!

Has anyone managed to find a mod for Sync IN? My guess would be to disconnect the timing oscillator and feed and external clock into the divider... Anyone tried it? It's be grea ...

9V battery project to Buchla module project

rogerlatur — Sun, 14 Apr 2013 11:57:10 -0600

Thank you very much for your help and advice.

Can someone familiar with Buchla stuff explain Quiet Ground and Noisy Ground?
Noisy GND is for digital circuits and Quiet GND for analog circuits.

CS-80 style VCO

steffensen — Sun, 31 Mar 2013 03:30:18 -0600

I have nothing to add here, only that im glad someone finally picked this up. Will follow with interest!

What's Uncle Krunkus up to now?

analog_backlash — Fri, 29 Mar 2013 18:36:42 -0600

Been out all day, so I'm a bit late joining in here.

Does anyone know what they mean in that schematic about a "telephone pickup"? I have an idea of what it looks like, but I haven't seen one for years. I may end up winding my own.
These are sti ...

Germanium Transistor opamp with FET

paulmorison — Fri, 22 Mar 2013 02:30:15 -0600

Hi
A few years ago, I came across a discrete opamp design, very simple, that had a Germanium transistor, a FET and a few other components-cant remeber if it looked like it would work properly, but would like to re-visit it and try it out
Anyone seen ...