40106 drone

[Deedalo12]

Hi, I want to do a little box with a 40106 cmos, wich oscilator slightly "out of tune" one each other, with different values ​​of resistor/capacitor , but I don't understand how I can mix all the signals in one output. Do I need an op amp?? or can I do it with diodes?

[PHOBoS]

Mixing can be done with resistors or diodes,. both have a different effect.

If you use resistors the output will be a varying voltage. The amplitude of this voltage depends
on the output of the oscillators (high or low) and the ratio between the resistor values you use.
You could use different values to mix the oscillators at different strengths but you could also use
specific values and configure them in a certain way to create an R2R resistor network. This would
result in an evenly distributed stepped voltage. https://hackaday.com/2015/11/05/logic-noise-digital-to-analog-with-an-r-2r-dac/

With diodes the output will just change between 2 voltages, so it's still a square wave, but the pulse width
will vary. Depending on the orientation of the diodes you're basically creating either and OR or an AND gate.
In theory they should actually sound the same but it depends a bit on how the signal is further processed.
Configuring them as an OR gate by connecting the Anodes to the outputs of the oscillators and connecting
the Cathodes together as your mixed output will likely give you the best results though.
NOTE: Don't combine different orientations! It could result in some interesting sounds, at least at first,
but you might end up with an overheated and likely damaged chip.

You could also use XOR gates to mix them together which will have a different sound.
Of course you could use any network of logic gates to mix the signals together but you probably want to start
with something simple so I'd suggest trying resistors first.



The need for an opamp depends on what you want to do with the signal and might not be needed.
Generally It would be a good practice to have some form of buffering on the output and a DC blocking
capacitor can also improve things but maybe for your purpose you can keep it simple.

This thread has some info on mixing signals with an opamp: https://electro-music.com/forum/topic-55327.html
You could also use a transistor to buffer the output as I did with the NANDulator

[Deedalo12]

tnx you im goin to try with the 2r2 ladder. Im a newbie on electronics, i have a few concepts but i think the experimentation can teach me a little.

Again, thank you!