We found this circuit in the August 1990 issue of Radio Electronics magazine. The two-digit circuit uses a pressure sensor and is powered by a 9V battery.
The circuit presented is a simple MW tuner that can be plugged into the input of any audio...
We find this circuit in a 1970s documentation on operational amplifiers. The setup is true for...
This amplifier was found in an 80s component manual. The circuit can be used for media recovery....