The transistors of this circuit found in a 1965 magazine can be the BC558 and the sensitive 12 V x 50 mA relay. The other components are common.
The circuit shown in figure 1 uses the ST8R00 from ST Microelectronics which consists of a 1 A...
We found this circuit in an old American documentation. Transistors can be modern equivalents. ...
This BFO or OFB for listening to SSB (Single Sideband) signals was found in the January 1996 issue...