Found in National Semiconductor documentation, this logarithmic meter is powered with a voltage of only 1.5 V. Equivalent operational amplifiers can be tested.
This circuit triggers the LED when the monitored battery voltage drops below 9 V for 12 V...
We found this circuit in a Radio Electronics from January 1967. The SCR is already the C106, which...
This power source with silicon diodes at a time when valves were still used was found in Radio...