Found in old American documentation, this circuit can use crystals between 27.5 and 33 MHz operating on the third harmonic. The transistor admits equivalent.
This circuit is suitable for SSB modulation and was obtained from an amateur radio documentation from...
This circuit was obtained in a 90’s Popular Electronics. The operators admit equivalents such as...
This 7400 TTL circuit has a memory, keeping the LED on when a pulse is detected. The circuit must be...