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8038 waveform generator
MUFF WIGGLER Forum Index -> Music Tech DIY  
Author 8038 waveform generator
revtor
Saw these IC's on sale and remembered S.Stites & T.Henry working out a nice implementation for them.

Linear VCO / Bench waveform generator. A great synth DIY workbench tool or "old school" Pre 1v/octave style audio generator

https://www.bgmicro.com/ICS1069.aspx

and..

https://www.birthofasynth.com/Thomas_Henry/Pages/8038.html#Features



~Steve
Orgia Mode
I'll have to check out that second link. I bought a load of these years ago and struggled to get a decent frequency range with what I thought were good rc values.
revtor
They get it 20-20k apparently. Some very creative manipulating of things.. Thomas Henry’s kinda known for that. Fun stuff to research..
jorg
I built my very first VCO around the 8038, back in the mid 1970s. It got fairly hot, and tuning was a pain because of the linear scale. But it did sound nice - and had a sine output right out of the chip.
Orgia Mode
jorg wrote:
I built my very first VCO around the 8038, back in the mid 1970s. It got fairly hot, and tuning was a pain because of the linear scale. But it did sound nice - and had a sine output right out of the chip.


I didn't run mine long enough to find out if it got hot. Definitely wroth a revisit now that I know so much more about electronics.
dot matrix madness
The 8038-based VCO on page 83 of Thomas Henry's (e)book "The VCO Chip Cookbook" shows better V/oct tracking than his other VCOs using that chip.
Anyhow, you can get a very pure sine out of the 8038.
I use mine often as "function generator" as input for other modules under test.
build photo here
Orgia Mode
dot matrix madness wrote:
The 8038-based VCO on page 83 of Thomas Henry's (e)book "The VCO Chip Cookbook" shows better V/oct tracking than his other VCOs using that chip.
Anyhow, you can get a very pure sine out of the 8038.
I use mine often as "function generator" as input for other modules under test.
build photo here


Oh, thats nice! I don't think I am familiar with that ebook. I definitely need to find it now.
KSS
Orgia Mode wrote:
I'll have to check out that second link. I bought a load of these years ago and struggled to get a decent frequency range with what I thought were good rc values.

You were not alone! We were all misled by the datasheet. At least when we look at it in hindsight. Everybody and their brother were publishing the same limited projects when these first came out.

Giving credit where it's due., John Simonton of PAIA was the one who discovered the way to get wide range out of these types of chips. Tom Henry properly credits him as source and has taken it from there. Simonton's work was pusblished in old Polyphony magazine articles. I think the 566 was the first place he used the idea TH has since documented and expanded.
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