This circuit was found in documentation from the 90s. The operational amplifier admits an equivalent. The circuit has frequency ranges up to 5kHz determined by R1.
This circuit, which can be used as a shield, was found in American documentation from the 1970s....
This circuit for low frequency data transmission was found in the May 1977 issue of Radio...
This circuit activates a relay that has a lamp as a load. The circuit is from a Radio Electronics from...