This circuit by Ferranti, in a 1967 publication, is intended for reading perforated tapes. The circuit uses transistors from the era that can be replaced by modern equivalents.
We found this circuit in the Linear Applications Handbook of the National Semiconductor of 1994....
The figure shows how to obtain a high impedance amplifier with unity gain using a JFET. The...
With this circuit it is possible to use a low current switch to switch on and off a high current...