This 80's Exar circuit has a carrier detector for frequencies up to 500 kHz. The circuit uses a company 567 which is still a common component.
This 3-digit thermometer, suggested by Texas Instruments, uses 3 integrated plus the display, with...
I found this circuit in an English magazine from July 1982. The circuit is still viable because all...
This 1965 circuit consists of a small inverter for an ultraviolet lamp. The circuit is from a...