This circuit for light modulated in frequency (FM) operating at 50 kHz was found in a 90’s Electronics Now. The circuit has an active filter. Modern equivalent transistors can be used.
This circuit can be used in a signal level indicator with LEDs. The circuit is from an Electronics Now...
This circuit for analog video signals was found in a March 1988 Radio Electronics. The Maxim...
This circuit was obtained in a 1960 transistor manual from Sylvania. The circuit can be...