Found in a 1980s American documentation, this circuit appears with variations elsewhere in this section. The circuit activates a relay according to the supply voltage.
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...