The integrated circuit used in this detector is uncommon today. We found it in a documentation from the 70s. Detection is done by an optical camera with LEDs and a photo sensor.
We found this circuit in the October 1980 issue of Radio Electronics magazine. The circuit uses...
Found in an English publication from the 1980s, this circuit uses components that are still common...
With two cascading tunnel diodes, this circuit found in a 196 General Electric documentation...