Hiya, I have laid out some cmos ic’s to create a S&H using a 4046, 40106 and a 4066 (Switch) I copied the schematic from Logic Noise: 4046 Voltage-Controlled Oscillator, Part One | Hackaday
but the sample and hold effect does not work sadly. But I do have some nice bubbly watery sounds though! Any ideas if the schematic is correct, or if you know of a different workaround. Any help will be much appreciated, many thanks. I have attached a jpeg of the schematic.
I have seen this circuit before and wondered what sort of noises it could make.
Im not sure if this is strictly a sample a hold circuit as ordinarily the switch would only close very briefly for the capacitor to sample the instantaneous voltage at its input. With this one the bottom oscillator ( U2b )controlling the sampling switch (U3A) is running as a squarewave oscillator so half the time its closed during which time the voltage from the top right oscillator can still vary, and thus alter the pitch of the 4046 vco. When it opens during the other half of the bottom oscillators cycle then the cap at pin 9 of the 4046 should stay at whatever voltage it was at at the end of the first half of the cycle, with the 4046 staying at a fixed pitch until the next time the switch closes, in this respect like that of a sample and hold circuit.
The bottom oscillator should probably be running slower than the top right one, that is the bottom oscillator should have a larger value of capacitor than the top right one, if you are aiming for the traditional S+H effect
Another possibility to make it more like the authentic S+H effect would be to add a diode pointing to the left parallel to the 100K pot of the bottom oscillator.
Your very kind for those comments and help. I will try these suggestions out on my breadboard. Byeee for now.
You’re welcome.
Let me know how it goes.