Looking at making a Chatterbox, a few questions

[AlessandroS]

Hi everyone,
I'm looking at making a Chatterbox, which would be my first DIY synth. I'm just wondering what supply voltage is required, and if the schematic on Yves' website is complete.
http://yusynth.net/archives/WirelessWorld/Chatterbox-1976.pdf

Thank you!

[PHOBoS]

oh, that looks fun,. I'll put it on my todo list
as for the supply voltage:

[AlessandroS]

Thanks for the response! Looks like I should look into making a power supply first.

[dave the butcher]

it would be cool to have such a device, if you design a pcb, would you be so kind to share it?

best regards!
David

[AlessandroS]

Thanks! I've only made a few small PCB layouts and never actually made one, but if I get to that point I'll post it.

[PHOBoS]

I think it could use some upgrading.
Replacing the 8 uA741's with 2 LM324's and the LM380 with a LM386.
The 2.5nF capacitor could be difficult to obtain so on a PCB it might be a good idea to add room for 2 capacitors (1.5nF + 1nF).

I noticed a small mistake in the schematic; the CD4002 in the noise generator section is drawn as a 4 input XNOR (which wouldn't work) but it's
of course a 4 input NOR (used as an inverter). The other half of the CD4002 is used as a 4 input NOR but followed by an XOR used as an inverter,
so it's just a 4 input OR. Instead of using those 2 gates you could use 4 diodes and a resistor to create a 4 input OR.
Then you can use the CD4070 gate as in inverter in the noise generator section instead of the CD4002 gate, eliminating the CD4002 altogether.

I want to redraw the noise generator section to see if it's possible to make the LFSR with another chip since the CD4006 seems to be harder to obtain
too (I still have a couple though). With the extra XOR available it might also be possible to extend it (make it more noisey).

And of course there is the option of making it voltage controlled by using OTA's for the filter section, but that would change the whole circuit dramatically.