We found this circuit in a 1973 documentation. The null adjustment trimpot is 10k. The circuit can be powered by symmetrical sources from 9 V. The diodes on the bridge can be 1N4148.
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...