This device was made to fit on my 4x and 10 x biological microscope planar microscope objectives, which are primarily designed to view slides. Accordingly, they have a relatively short focus and high numerical aperture.
The circuit presented here uses bicolour LEDs to generate a display in three colours, namely, red, green, and yellowish green. Transistors T1 through T20 form a grid to which common-cathode bicolour LEDs
This charger for series-connected 4-cell AA batteries automatically disconnects from ains to stop charging when the batteries are fully charged. It can be used to charge partially discharged cells as well.
In three-phase applications, if low voltage is available in any one or two phases, and you want your equipment to work on Normal voltage, this circuit will solve your problem.