In his latest video, Jan Beta is building a simple 555 timer-based logic probe using spare parts he had lying around. He opts for an ILC555 chip instead of the original NE555 and replaces the 1N914 diodes with 1N4148s.
The original schematics from ETI (November 1979) can be found here: Original Schematics
An updated version is available on Instructables: Updated Version on Instructables
