Found in a 90s documentation, this circuit makes use of D1, a switching diode that is uncommon today. D3 is an LED. The circuit monitors 12 V batteries.
This circuit was found in ancient American documentation. Diodes are general-purpose types. |...
This 80's General Electric circuit is guarded by the noise-guard for operating current. The...
This circuit was found in the January 1975 Radio Electronics magazine. The diodes are current...