This sophisticated circuit with two LF411 operational amplifiers appeared in the November 1984 issue of Radio Electronics magazine. The circuit uses a Mallory buzzer as an indicator.
This circuit for monitoring telegraphy transmissions was found in a 1975 CQ magazine. Transistors may be...
The integrated circuit used in this application is like the 555. The components depend on the...
The circuit presented is a simple MW tuner that can be plugged into the input of any audio...