Yes, no worries! I’ll measure the resistance curves with different LDRs and LEDs, and test the sensitivity to external light. My plan is to pop them in a LPG first, but I’ve been thinking of other applications for a 4-way vactrol. One would be a bank of sine-wave generators, using a circuit like this:
At any rate, I’ll post all designs here as usual!
A couple possible pitfalls with that circuit — First, the LM380N is an audio power amplifier intended for driving a speaker at fixed gain. It may not produce signals suitable for synth use. Second, the frequency is governed by R2–R4 and C1–C3 — you’d need a triple gang pot to vary the frequency manually.
Yeah I must say I haven’t put too much research into it yet. The 3 RCs I’m aware of, but that’s the whole idea. These are 4-resistor vactrols, so they can be used for voltage control. That being said, no way it’ll ever be 1v/oct. I was thinking, maybe tacking 3 or 4 together with individual VCAs and AD envelopes can make for some interesting percussive sounds, perhaps like church bells?
Maybe I’m misunderstanding your idea, but if you’re thinking of using three vactrols to vary the frequency, keep in mind they’d have to all produce the same resistance as each other as the control voltage changes. That means the LDRs would have to be consistent, and the packaging would have to be set up to make them all see exactly the same amount of light. Maybe that’s not difficult, I don’t know. But I wouldn’t assume so.
Yes they’d have to be pretty well matched, I have no idea how difficult that will be, testing will show. There’s no real module idea here yet, just some loose collection of concepts. Also, right now I’m trying to think of modules to match a part, which is kind-of the wrong way around. Like looking for nails just to use a hammer. Anyway, maybe I should post them in the odd parts thread.
This could lead to interesting colouring of the sound, so the harmonics / overtones would change with the frequency. Could be worth a breadboard session.
A twin T oscillator would be a similar design requiring 3 resistances to change. It looks like a fun idea, and I just want to see these in a rack 
Congrats on the birthday! Have fun with the keystep!
Thanks all, yes i’m really like a little child with my new toy 
Pretty sure a jiffy bag would’ve sufficed…
Edit:
And a multimeter just turned up. Figured the AN8009 was one better than the AN8008, plus it was a fiver cheaper.
“This multimeter goes to 9!”
yeah it is crazy the packaging some times .
I once ordered 2 16 pin SOIC chips from Arrow. They arrived in an anti-static bag in a clear bag covered in bubble wrap in packing pellets in a box like that.
Once bought a job lot of dip ic’s which arrived in a plastic bag. No padding at all. Just a flattish blob of plasticine with all the chips pushed into it. Good times.
A truly massive order from LMNC and Thonk… B10K pots, so I can actually breadboard those SSO’s properly.
Last weekend I decided it was about time I made some of the Kosmo modules designed by the community. I swapped some boards and ordered some via JLC. Today in the mail I got this little lot, a set of @CTorp K25 series modules. I just need to find a supplier for the sliders who wants to sell me less than 750 units, I don’t fancy my luck trying to sell 748 of them on Ebay
Where are you located? Mouser has them.
