This circuit was found in a Mallory documentation from 1968. The integrated circuit is of the time, unusual in our day. Input sensitivity is 20 mV for 2 W output.
This indicator with the integrated circuits CA3162E and 3161E was published in the July 1990 issue...
September 2016 - It can be purchased at Mouser Electronics the new REF6000 precision voltage...
This simple two transistor timer can be used to measure short time intervals. The power supply...