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 timing circuit was found in old documentation. The technology is CMOS. The supply can be made...
This circuit was found in a 1967 General Electric documentation. Tunnel diodes can oscillate at very...
This circuit can be used in a signal level indicator with LEDs. The circuit is from an Electronics Now...