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 traditional detector configuration is from an old publication where the MC1555 is the...
This two-transistor emitter-coupled oscillator circuit with capacitive feedback was found in the...
If the reader is skilled, he can mount this spy micro-transmitter with SMD components and obtain an...