The circuit shown has a voltage gain of 500 times and can use equivalent FETs like the BF245. The circuit is suggested by National Semiconductor in its 1994 Linear Applications Handbook.
Found in an Electronic Design from the 80's, this circuit monitors the charge of a 12 V battery....
Found in an EEE from 1970, this circuit supplies a voltage of 12 V DC x 10 mA current from the...
Using old germanium transistors like the CK722, this circuit has good gain. We found it in a...