Title: Battery lift magnet control

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Abstract: A lift magnet for a lift truck, crane, etc., energized by a battery, and a transformer and rectifier are provided for charging the battery from an AC source; a transistorized circuit is included; a SAFE signal light is provided and controlled by a first transistor in services therewith; the transistor is normally conducting and when a failure occurs the transistor becomes non-conducting and the SAFE signal light de-energized; the failure may be from low voltage condition of the battery, or such defects as a break in the circuit or switch means, such as would prevent proper operation despite full voltage; also, before the electromagnet is fully energized, and the current therefore is low, an UNSAFE signal light indicates such low current condition; a second transistor is provided in series with the UNSAFE signal light, this second transistor being normally held in non-conducting condition by the first transistor; when an UNSAFE condition results the first transistor de-energizes the SAFE signal light and in the same operational step renders the second transistor conducting which thereby energizes the UNSAFE light; a zener diode is incorporated in conjunction with the transistorized circuit for providing a stabilized voltage therefor.


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