M 1s Unit. The M 1s (?????? als sparschaltung) is merely an improvement over the normal M 1 by the use of a different anti-countermining circuit. The magnetic brake of the latitude adjustment escapement is fitted with a single-pol-single-throw normally-clo-sed switch, which converts it to a normally-closed releay. In the normal M 1 and anti-counterining reaction was caused by movement of the gimbals which operated the pen-dulum switch; thus the hold-off coil and air-core relay were energized. The hold-off coil assured that the needle did not make contact, and the air-core relay closed the electro-magnet switch, thus stopping the escapment of the latitude adjuster. The current which flowed in these two parallel circuits was approximately 0.5 amperes. This was considered excessive. In the M 1s, the hold-off coil is energized only during the latitude adjustment process if the needle sticks to its contact. Closing of the pendulum switch energized the electromagnet directly, stopping the escapement and opening the ALA switch. Thus, un-til the hold-off is de-energized, no closing of needle contacts can fire the mine. One coil of the air-core relay and its corresponding contact are un-used. In this circuit, the bat-tery drain is approximately 50 ma. instead of 500 ma.