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.
Based on 4066 CMOS, we found this circuit in a Popular Electronics from 1992. The signal is...
This receiver of two transistors for the 3.5 MHz band was found in a circuit manual from the 80's....
This circuit uses an unusual Motorola integrated. The circuit is from Motorola's 1990 Linear...