Figuring out the circuitry of old DIY drum synth

video upload by organfairy

"I play it manually at 3:23 and run it with a step sequencer at 4:17.

This is another un-documented one from the vaults - one that I, for some inexplicable reason, have not made any written information about.
So in this video I go through it and find out how it is made.

The music is 'No Hollywood movie', originally recorded by Lesley Hamilton, that was a hit in Germany in 1978. Same year it was recorded in Danish by Gitte Hænning as 'Hollywood drømme' and in German as 'Von Hollywwod Träumen'. I play it on my Yamaha HE-8 organ with Korg Rhythm 55 drum machine - but I probably didn't do a very good job since YT couldn't recognise it..."