The ports used in this ultrasonic remote-control transmitter are TTL, requiring a 5 V supply. The transducer is a piezoelectric type, not very common today.
This circuit was obtained in a 1979 101 Electronics Projects. The circuit can be assembled easily,...
Suggested by a 90's Linear Databook, this circuit compensates for capacitor hysteresis. The main...
This circuit serves to isolate analog signals, for example, audio signals in a secure link...