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Solenoid Coil Driver

IP.com Disclosure Number: IPCOM000093885D
Original Publication Date: 1966-Mar-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 23K

Publishing Venue

IBM

Related People

Mueller, FE: AUTHOR

Abstract

This solenoid drive circuit provides a high initial current to achieve pull-in. A lower sustaining current is realized for the remainder of the actuated period. With switch 1 open no coil current flows and capacitor 2, having a value of 1 mu fd. charges through resistor 3 of 150 omega to almost the supply voltage. Resistor 4 is seven times larger than resistor 3. When switch 1 is closed, diode 5 is reverse biased and capacitor 2 supplies base current to transistor 6. Conduction through transistor 6 and resistor 7 supplies a high current to solenoid 8 until the charge on capacitor 2 is dissipated. At this point transistor 6 cuts off and holding current to solenoid 8 is maintained through resistor 3.

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Solenoid Coil Driver

This solenoid drive circuit provides a high initial current to achieve pull-in. A lower sustaining current is realized for the remainder of the actuated period. With switch 1 open no coil current flows and capacitor 2, having a value of 1 mu fd. charges through resistor 3 of 150 omega to almost the supply voltage. Resistor 4 is seven times larger than resistor 3. When switch 1 is closed, diode 5 is reverse biased and capacitor 2 supplies base current to transistor 6. Conduction through transistor 6 and resistor 7 supplies a high current to solenoid 8 until the charge on capacitor 2 is dissipated. At this point transistor 6 cuts off and holding current to solenoid 8 is maintained through resistor 3. When switch 1 opens the capacitor charges very rapidly through resistor 3 and the circuit is ready for a repeat in a fraction of the discharge time constant. Diode 9 and resistor 10 provide for arc suppression.

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