We found this circuit in a 1977 National Semiconductor Databook. The circuit can use other FETs like the BF245 and has an input impedance of 10 megohms. The circuit gain is unitary.
May 2017 - The new 36V TLVx171 Series of General Purpose Operational Amplifiers from Texas...
This circuit has a voltage gain of approximately 100 times and can operate with medium and high...
This was the name given to the Darlingtons in the 1950s. The circuit is from a November 1952 Radio...