This circuit was found in a Radio Electronics from April 1990. The circuit has 5 equalization bands given by the capacitors used.
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...