Suggested by a 90s EDN, this circuit supports almost any LED as a source and a phototransistor as a detector. The circuit operates with a PLL 567 at a frequency of around 40 kHz.
This Mullard circuit was found in a 1969 documentation. It uses complementary transistors on the output and...
This circuit was found in an American documentation from 1968. The configuration can be adapted to...
We found this configuration in the Linear Applications Handbook of the National Semiconductor of...