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 found in a 1999 publication. Its purpose is to flash two LEDs according to the...
This circuit is based on the well-known digital module ICL7107 feeding 4 displays with...
This configuration can be found in other articles in this section. This was obtained in a 2000...