We found this circuit in a 1977 factory documentation. The operational amplifiers can be 741 and the symmetrical power supply. Capacitors can be changed for operation at other frequencies.
This circuit was found in Popular Electronics. Its purpose is to warn the visually impaired when a glass...
This circuit was obtained from a Popular Electronics from January 1967. It has a...
This ultrasonic transmitter was found in a 1974 documentation. The receiver is the CIR11753 or...