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.
Found in old documentation, this circuit applies to almost any common operational amplifier or...
Found in Harris' 90s documentation, this circuit uses a zener as a stabilizer. The signals...
The circuit is from a 1978 publication and the transistor may be the BC558. The transformer is...