The operational amplifier of this circuit can be the 741. The circuit has very low consumption and can be powered by two 9-B batteries. Low voltage amplifiers can be used.
This circuit receives the local stations of medium waves listened to in a piezoelectric capsule or...
This circuit was published in an 80's American documentation, but it is still current. The power...
This simple neon lamp power indicator circuit was found in the January 1971 Radio Electronics...