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Magnet Driver

IP.com Disclosure Number: IPCOM000090702D
Original Publication Date: 1969-Jun-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 25K

Publishing Venue

IBM

Related People

Hesse, KO: AUTHOR

Abstract

The magnet driver applies full power supply voltage across a magnet. Such occurs while work is done by the magnet to move its armature and subsequently switches to apply a lower RMS hold voltage on the magnet to thus lower the IR heat losses. The magnet driver comprises switching bipolar transistor 10 and diode 11. The transistor has emitter 12, base 13, and collector 14. The magnet 15, which is to be controlled, has its magnet coil 16 connected across diode 11. Twisted wire pair 17-18 connects power supply 19 with transistor 10, diode 11, and magnet 15. Control lead 20 is connected to base 13 through resistor 21. In operation, when lead 20 is raised by application of a six-volt signal 22 to it, the full voltage of power supply 19 is applied across coil 16 to cause magnet 15 to do work.

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Magnet Driver

The magnet driver applies full power supply voltage across a magnet. Such occurs while work is done by the magnet to move its armature and subsequently switches to apply a lower RMS hold voltage on the magnet to thus lower the IR heat losses. The magnet driver comprises switching bipolar transistor 10 and diode 11. The transistor has emitter 12, base 13, and collector 14. The magnet 15, which is to be controlled, has its magnet coil 16 connected across diode 11. Twisted wire pair 17-18 connects power supply 19 with transistor 10, diode 11, and magnet 15. Control lead 20 is connected to base 13 through resistor 21. In operation, when lead 20 is raised by application of a six-volt signal 22 to it, the full voltage of power supply 19 is applied across coil 16 to cause magnet 15 to do work. Transistor 10 is switched on continuously during this magnet work cycle. The signal on lead 20 is alternated between zero and six volts after the work to be done by magnet 15 is complete. Transistor 10 is switched repetitively off and on during a chopping or magnet-hold cycle, providing voltage pulses across magnet coil 16. The latter integrates these voltage pulses into a relatively constant current, assuming the on-off cycle of transistor 10 is kept short relative to the L/R constant of magnet 15, so as to provide a reduced current through magnet 15 as shown by current waveform 23. Diode 11 commutates the current from magnet coil 16 during the time transistor 10 is...