This circuit is better than the previous one in that the control is isolated by a transformer. The transformer has 110 or 220 V primary and 6.3 to 12 V secondary with 200 to 500 mA current.
This filter is suggested by Motorola's Linear Interface ICs of 1993. This same configuration...
This circuit was found in the March 1980 issue of Radio Electronics magazine. It is based on the...
This circuit not only indicates when the battery is on but also when it is low. The circuit is...