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 circuit is from an English publication from 1973, but can be easily assembled today. 2N718 can...
The integrated circuits used in this 1989 project are uncommon today, including the IF coil that...
We found this receiver for the 144 MHz band in a European publication from the 1970s. The circuit...