Found in a 1964 Electronic Design, this circuit makes use of FETs of the time. These transistors can be replaced by modern general-purpose types. The input resistance is 30 M.
This circuit is from an old National Semiconductor component manual. The circuit can be...
Found in Radio Electronics from the 90s, this circuit uses components from that time. However, it...
This circuit has been found in older telecommunications documentation. The circuit switches off after...