This circuit was obtained from a Radio Electronics in February 1965. The circuit uses two transistors from the time and can be created with modern equivalent transistors.
Found in an Electronic Design from the 90s, this circuit uses high voltage operationals of the...
This circuit was found in the July 1990 Radio Electronics magazine. It is based on the 3-digit...
The circuit shown in the figure uses two of the four operational amplifiers found on the LM324...