Robot sound audio circuit of the 1990s: does it work or can it work? (demo, principles & schematic)

Merry Christmas everyone! We live say 18 december 2021.

Please read the textbox. The video tells everything. A 1 NPN transistor circuit (with a standard NPN transistor, Hfe must be say 250 – 300) that works, driven by a squarewave generator with an output amplitude of 1-4 Volt AC, it can generate a kind of “robot sound”. Important: in the original schematic of the 1990's there is a flaw: they indicate the decoupling capacitor in the power lead as a time dependent capacitor, that is not right.

Important correction: I constantly say in this video that the max. output of my square wave generator is 1 Volt, but it was 10 Volt. I leave the video as it is, because all depends on the saturation voltage of the used NPN transistor that does the ""chop work". At its base the voltage to make it "chop" is tiny, say in the 0.8 V - 2 Volt range.

I used now & here in the demo my Farnell 0-1 MC sine/squarewave generator, but there are many (!) circuits on my YT Channel where you can find how to make a square wave (or comparable useful circuit for this case) generator.

Even with a higher AC output voltage, so higher than 1 Volt AC. Search e.g. via the “looking glass” on my Channel trailer (Radiofun232 on You Tube) with keywords like “oscillator” or “generator” or “square wave” or “square wave generator”.

With a variable voltage square wave generator with a variable output in the 0,8 Volt- 4 Volt or higher output range range you can change the saturation level of the (here BC 547 b) transistor that does the “chop job” in a very/perhaps more precise way.

That could give a better results when we are talking about chopping off audio signals and creating ”robot sounds”.

After studying my Farnell generator (afterwards, later than this video) the max output that it could give was maximum 10 Volt. Anyway, that is not very relevant for the content of this video, where the focus is on "how to make it" and audio chopping is in the 2-4 Volt range on the base of the BC 547 b NPN transistor.

I did not do exact measurements about the real voltage entering the base of the "chopping" transistor because the circuit worked directly .

When you have questions about (certain analog) electronic circuits and how to make them: go to my Channel trailer (Radiofun232 on You Tube) and go to the “looking glass”. Type there the keywords that you want/need like: “power supply”, audio amplifier, capacitor tester, oscillator, radio, shortwave, shortwave radio, or any keyword you like to find the essential info & schematics on my YT channel.

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 18 december 2021.