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.
Found in American documentation from the 1970s, this circuit can be designed based on a modern SCR,...
June 2017 - A wide variety of Rohm Semiconductor audio and codecs for audio is available from...
Found in a 1964 Electronic Design, this circuit must use transistors according to the supplied...