Experimental CD4018xx Suboscillator

[zaphod betamax]

Here is a circuit I came up with with the CD4018xx as a suboscillator.

The waveform is harmonically related to the input square.

It is an odd circuit as I was originally poking around with the CD4018AE that I have and trying to find DC bias points but came up with this instead.

It also works with the CD4018BEs I have hanging around.

Dreadfully simple circuit to breadboard.

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[PHOBoS]

interesting,.
at first glance it looks like your standard shift register/divider + resistor setup like discussed in this thread but then
I spotted the feedback connection into the input pin.
I was slightly confused as you're controlling a digital pin with what is basically an analog voltage but I guess it works
in this case because that voltage is created with only 3 digital signals. If it was 4 you'd get a voltage that would be at
±50% of the supply voltage which would likely confuse the chip. Does make me wonder what happens if you'd add a
capacitor to smooth out the voltage, might create some interesting effects.

It does feel slightly wasteful since the chip is basically locked into the same pattern while it would be able to do more
but on the other hand it's a really neat simple 1 chip circuit that can spice things up a bit.

[PHOBoS]

I think that the addition of 1 more chip and some DIP switches could give you more bang for your buck without going overboard.
it's likely that not every one of the 256 switch combinations will sound very different but it might be worth testing to see or rather
hear if there are some nice sounding ones.

I didn't really look into the CD4018 (don't know if I ever used it though I do seem to have it) but I think that if you would close
switches 3,5,6 it should behave the same as the original circuit.
Since the control signal for the input of the CD4018 is now taken before the resistors you could change those resistors or even
use something like an R2R network. Potentiometers would also be an option but that all takes away from the simplicity of the circuit.


note: the CD4512 has a more convenient pinout for use with DIP switches than the CD4051 but is less common.

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[zaphod betamax]

Thanks for your addition, I was late getting back as the notification went to spam for some reason.

I mainly was experimenting with the CD4018A as I was giving a decent
amount of select CD40xxA and I have 5 of these CD4018As.

I was actually poking about attempting to see what I could DC bias as these
were A series very much like the UB series.

I did one last experiment at higher voltages (12V) and really it did not work too well.

However, as an experiment, is it in the archives for future exploration.