Each generation has a musical instrument to define its own voice. For those whose music was formed in the 1980s, the Roland tr-808 percussion instrument synthesizer is a strong competitor for the crown. Its voice can be recognized in a series of popular music of that era, and every decade since then. Although the original instrument was not commercially successful, it can still be obtained through sample kits, simulations and cloning. 808 is a fully analog device without samples, so [mark Longstaff Tyrrell] can reproduce its unique cow ring tone according to some original circuits.
We shouldn’t be surprised when we find that the circuit is very simple. The trigger pulse is converted into an envelope that controls a pair of oscillators. The hybrid output passes through a band-pass filter to produce a unique sound at the output, which you can hear in the video. The circuit was recreated on a test board. The only concession to modernity is to replace the original Schmitt trigger oscillator with a microcontroller.
In general, it provides us with a fascinating insight into the synthesis behind the classic sound, and makes us appreciate the design skills of Roland engineers. We’ve seen 808 several times before, including an explanation of a famous faulty transistor that causes its sound.