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.
Suggested by Texas Instruments, this circuit operates with frequencies that can reach some...
We found this circuit in a Popular Electronics of the 80s. The circuit can be made with almost any...
This simple low power stage with output transformer was found in an American documentation. The transistor...