TAP Elektor Article and SchematicJul 5, 2016 resources p05-tap
Contributed by @boldport on Jul 5, 2016
The functionality of the circuit is comprehensively and beautifully explained in the original article from Elektor magazine in English, December 1974. Here is the article as a PDF, and it’s really worth reading. Here is the schematic I re-created for the board.
We haven’t made any changes to the circuit, and remarkably all of the same components are still available today, including the original 7400 IC!