We found this circuit in the March 1980 Radio Electronics magazine. The circuit used is the HA2400 released at the time. The power supply must be symmetrical.
This circuit monitors extra-low frequency (ELF) fields. We found it in an American documentation from the...
We can use any type of resistive transducer with central resistance in the range of 10 k ohms to 1...
This circuit controls two lamps so that when one increases in brightness the other decreases. The...