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 with Triac causes an ordinary incandescent lamp to flash rapidly at a frequency set...
This is an improved version of the previous circuit that includes speed control. The engine can be...
This circuit allows feeding a small semiconductor laser to obtain a useful resource for...