Found in Mallory documentation from 1968 this circuit uses an integrated circuit from that time. The circuit has a flat response from 10 Hz to 700 kHz.
The TL431 integrated circuit consists of a programmable shunt regulator with an internal...
This circuit was found in a 1962 publication. At the time there were high voltage batteries like the...
This circuit was obtained from HAM Radio magazine in an 80's issue. The FETs are types of the time...