Found in Texas Instruments documentation from the 90's, this circuit can be used as a shield due its symmetrical power is 5 V. The circuit has offset adjustment and a pass band of 200 kHz.
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...