Through the TTL output this circuit can be used as a shield. The sensor is a platinum probe, and the operational amplifier can be replaced by a modern equivalent, preferably of low voltage.
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...