DIY Noise Gen?/Use x0xb0x as a programmable LFO

Anyone know of a simple cheap noise generator?
White/Pink/Whatever? That I can then feed through a synth with ought noise?

Also just finished my x0x and just wondered, if I feed the CV out into the CV Fitler in on my modded MC202 would that make it a midi sync’d programmable LFO?

In my day we just used to use a noisy transistor followed by a small preamp :wink:

Martin

That’s still the method of choice. There’s a simple and effective one in the SH-101 service manual, or if you really want to explore the subject there’s a great book by Thomas Henry: The Noise Generator Cookbook

The old 2N2712 or some such was a superb noise maker.

The Noise IC MM5837 used by the Buchla 266 is not recommended, it repeats its digital LFSR noise too often so it sounds like a choo-choo train. Electric Druid has an improved PIC that doesn’t repeat. Or you can use a good old CD4006-based digital noise like in the TR-909 and more for some digital noise.

Please note that the MM IC, the CD4006 and the 2n2712 are difficult to get hold of.

You could get any small chineeese budget mixer…

here’s the white noise section from Ray Wilson’s Experimenter board, low parts count, should fit on a small piece of veroboard:

:http://www.musicfromouterspace.com/index.php?MAINTAB=SYNTHDIY&VPW=1270&VPH=773
actually just a transistor with floating collector and buffering.
the pic is linked to the project page

…and here’s an even simpler (but somewhat ancient one by the look of it) circuit with switchable white/pink noise:

Martin

That looks the ticket. So just sort a power supply that does 15v to that and put a pot before the output

It should work just as well with 12V.

There is already a Pot in the Feedback Loop of the 2nd OpAmp. You may as well use a TL072 or better (more Noise) LM 324

Juu juu, but the 4558 is old and has some kind of “character”. LM324 has such low slew rate that it probably takes weeks for the signal to rise or fall… Instant random LFO.

You mean the LM324 is the focault pendulum of OpAmps?

Well, I exaggerated - a little. Any 741-derivative like the 4136, the low-power versions like LM324, LM358 is poor. The low-power versions will start to make triangular waves of anything above 5kHz, so it comes with a built-in low-pass. The class b output with up to 3% SNR isn’t helping either…

2SC372 are quite expensive, since they are a replacement part for a HAM radio… Although most transistors would do, wouldn’t they?

For those reverse biased noise generators, yes. Try a garden variety 2N3904 instead of a 2n2712 or this 2SC372 NPN.

Agreed - let’s face it, all this first transistor does is produce noise, so you could try anything in there - if it doesn’t produce much noise you just turn up that pot to alter the eventual output level :wink:

Martin

I should just amplify the noise my desk fan spews out, turning it off can be heard on speakers all over the grid in this house… :confused:

Transistors are so future…only real matter gives real noise!

…or you could have several switched devices - what about being able to choose from germanium noise or silicon noise!

Martin

@frank: LURVE that laser link

Martin

@fcd72
Very interesting and good idea for a noise generator :slight_smile: