Simple audio synthesizer: how to make it part 3 (VLOG and schematic with a 555 Chip and demo)

Please read the textbox. Project to make a simple audio synthesizer, video 3.
It shows a more elaborated circuit with a 555 Chip after many experiments during the past days, both by getting (in a simple way) an audio generator with a good amplitude over a long audio frequency band (20 Hertz-12 KC) and more. Don't forget the wire between pin 2 and 6 of the 555 (!!).

About the (obsolete) N-FET BF 245 a,b,or c, You can use a BF 256 b (not obsolete, also a N-FET). Pin connections are the same.

Problem is always: the output amplitude changes with the frequency of the generator(s). But there must be a kind of constancy.

Video 2 (showing frequencies generated by a TL 071 FET Opamp) is here: https://youtu.be/Ud2WjJGgaHE

Video 1 (showing a 3 Muvib circuit that has to break into harmonic or not harmonic base sounds in this synthesizer) is here:

Please read the textbox. An update and only a VLOG, telling something about the development of the simple audio synthesizer. It will be made with 3 or more Muvibs and a sine wave/square wave/triangle wave generator that has to make the “base tones” in the audio range. To which other sounds will be superposed + a combination where two sine wave tones can be played at the same time to get to a more harmonic/disharmonic complete output sound.

Now (in this video 3) I am working to make the basic (sine) waves that have to be generated. Idea is to make square waves with a 555 Chip and filter them through a 3 pole filter (making sine waves) or make triangle waves and filter them out (into sine waves).

I have abandoned my first approach (with the TL 071 FET Opamp) to make square waves and push them through a 3 pole filter. Not because it did not work (it works good !) but because the frequency setting was too critical via that 100 K or 1 M potentiometer (is explained in vid 2).

Now I will use a 555 Chip to make waveforms in the 50 Hertz-16 KC range and want to push them through a 3 pole filter to change square waves (or triangle waves) into sine waves. Or use the original waveforms in the output sound of the synthesizer.

The good property of this approach is that we can switch between 3 different waveforms that all have their specific properties:

a) Square waves give many harmonics, thus many mixing products of the ground waves, even into the very high (say Shortwave radio) frequencies, sound = sharp
b) Triangle waves. They give a kind of soft-sharp tone, a kind of mediation in-between sine waves and triangle waves
c) Sine waves, they (only) have a limited number of harmonics and these harmonics are weaker, their sound is soft

So base tones combined with fierce Muvib tones, that will be the first aim. Perhaps also speech can be mixed into the output, finally into the synthesizer. Idea of Barry Blod, thanks Barry. Anyway, many things to explore.

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.


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 7 January 2022.
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