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 simple MW radio was found in a 1975 publication, but it can be mounted with BC548...
The coil and sockets of this circuit found in a QST depend on the frequency band that is intended...
The 4066 is better than the 401 B because the 401 B has a lower internal resistance when the...