This ultrasonic digital remote-control transmitter was found in the January 1976 issue of Radio Electronics magazine. The components are from the period. The IC is from the period.
Using components from the era, this 90's EDN circuit is used in analog to digital conversion...
Found in an American publication from the 90s, this circuit allows the supply of 3, 6 and 9 V...
We found this circuit in an old Popular Electronics. The circuit is experimental, driving an LED...