The sensor used in this circuit is uncommon today, however equivalent types can be tried. The comparator also supports modern equivalents. The circuit is from 80's documentation.
The time the output is high (1) of a TLCSSB in the astable configuration depends on Ra and C. The...
Found in a publication from the 60's, this power supply has no regulation, but only current...
This short-range circuit can act as a wireless microphone. We got the schematic and the printed...