Using an operational amplifier of the time, this circuit was obtained from a 90s Radio Electronics. The circuit covers the frequency range from 2 Hz to 20 kHz.
Found in American documentation, this circuit from the 90s uses components from that time. The...
This circuit was found in a 1980s documentation. The operational amplifier is of a common type at the...
This simple audio and RF signal tracker was found in a Japanese publication in 1967. The...