Crazy sounds box alias simple audio synthesizer demo and schematic (part 1)

In a video of a few days ago I demonstrated an old schematic that I published may years ago on You Tube. It is a sound box/simple audio synthesizer with 3 multivibrators. So a schematic with which you can make peculiar sounds.

In this (third) video I have worked it out again and give a (new) demonstration about how to make this audio generator circuit and how it sounds, when mixing 3 frequencies together. Say:

(A) Range 200 Hertz-800 Hertz (100 N caps, Muvib 1)
(B) Range 8 KC-10KC (47 N caps, Muvib 2)
(C) Range 1 Hertz-10/20 Hertz (10 uF caps, Muvib 3)

In all cases a potentiometer of 50 K or 47 K makes it possible to set a certain frequency in the audio band.

These frequencies are “mixed” into the second transistor of Muvib 1, the 1 Mega Ohm potentiometer plays a key role here, also by pinching off the frequencies/driver voltage. It has an effect on the duty cycle + effect on the steering (voltage) level.

Very important on the sound spectrum: the voltage supply (between 4 Volt and 12 Volt) to the circuit. Make it variable! To to get the most / more audio effects.

You can set very peculiar sound effects with the circuit, I cannot demonstrate them all because there are too many frequency and driver parameters, say 8 tunable effects (3 caps, 3 potmeters, 1 supply voltage, 1 drive level) on the audio (sound) that leaves the circuit.

Especially by changing the capacitor values in Muvib 3 (now 10 uF) you can get to a lower “drive” frequencies, say in the "slow whoop" range. E.g. make them 25 uF or 100 uF.

Many more sounds can be generated with the "wire with a capacitor in-between", with at the ends 2 crocodile clips.

Please note: when experimenting/soldering/wiring/testing it is well possible that you, by accident, connect the base of a transistor directy to the (+). The transistor will be directly defective (!). It happened to me, I could throw 2 transistors away during this experiment.

First video of 2014 is here https://youtu.be/DeEFlyEvfW8
Second video (31 december 2021, showing the principles and the parameters in the textbox) is here https://youtu.be/KisdQ0mednI

My You Tube channel trailer is here: https://youtu.be/xbgQ8T3oqh4 When you search, search always “NEWEST FIRST” to get the right overview. You can also search via the “looking glass” on my Channel trailer via keywords like ”audio”, “radio”, “amplifier”, “filter”, “Shortwave”, “transistor”, “FET”, “oscillator”, “generator”, “switch”, “schmitt trigger” etc; so the electronic subject you are interested in. My books about electronics & analog radio technology are available via the website of "LULU”, search for author “Ko Tilman” there.

https://www.lulu.com/search?adult_audience_rating=00&page=1&pageSize=10&q=Ko+Tilman

I keep all my YT videos constant actual, so the original video’s with the most recent information are always on YouTube. Search there, and avoid my circuits that are republished, re-arranged, re-edited on other websites, giving not probable re-wiring, etc. Some persons try to find gold via my circuits. I take distance from all these fake claims. I cannot help that these things happen. Upload 4 January 2022.

correction: on 0.39 I say "such a sine wave" but I mean of course "such a square wave".