We found this circuit in a 1964 Electronic Design. It provides 0.5 V signals from 4 kHz subcarriers. Transistors are from the era.
Found in a 90s nHands On Electronics, this circuit triggers a relay that shuts off the load when...
Another of the many similar configurations we have in this section. This one is from a Radio...
This circuit for incandescent lamps was found in the January 1980 Radio Elecronics magazine. The...