This circuit was found in an Electronics Now of the 80s applying to NiCad batteries of the time. The circuit is powered by a 12 VAC source, for example, the secondary of a transformer.
This Philips commercial circuit is from the 90's documentation. The integrated circuit must be...
We found this circuit in the September 1971 issue of Radio Electronics magazine. The sensor is an...
This circuit is from a Hands-On Electronics from 1987, but it can still be easily assembled, as...