The microscope needs 5-6VDC, 200-1000mA tip positive electrical input. The jack should be 5.5 mm OD, 2.1 mm ID, approx 12.5 mm long. If the jack won't insert due to being too loose or too tight, the microscope’s female jack has a central split male pin that can be spread slightly or pressed together for better electrical contact.
Updated 12/18/13