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.
For the 600 kHz range coil is formed by 35 turns of 28 AWG wire on a ferrite core with a diameter...
Found in a 1970’s documentation, this circuit uses components of the time, uncommon today. |...
This 2003 circuit uses two types of sensors: by reed-switch and by infrared. If the magnetic...