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# Stopping Control for Printed Circuit Motor

IP.com Disclosure Number: IPCOM000090547D
Original Publication Date: 1969-May-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 27K

IBM

Agin, GJ: AUTHOR

## Abstract

Stopping a printed circuit motor is accomplished by reversing the direction of the armature current. The reverse current is terminated at the proper time to eliminate coasting. This time is usually implemented by a single-shot which is adjusted to give minimum coasting. This circuit integrates reverse armature current to determine the optimum stopping time. Transistor T2 is normally biased to conduct and short out capacitor C. At the initiation of the stop interval, T2 is biased off allowing C to charge. R1 is a current sampling resistor in the armature circuit of a printed circuit motor not shown. Transistor T1 and resistors R1 and R2 are a common base current source. The current at the collector of T1 is proportional to the current in R1 in the ratio R1/R2.

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Stopping Control for Printed Circuit Motor

Stopping a printed circuit motor is accomplished by reversing the direction of the armature current. The reverse current is terminated at the proper time to eliminate coasting. This time is usually implemented by a single-shot which is adjusted to give minimum coasting. This circuit integrates reverse armature current to determine the optimum stopping time. Transistor T2 is normally biased to conduct and short out capacitor C. At the initiation of the stop interval, T2 is biased off allowing C to charge. R1 is a current sampling resistor in the armature circuit of a printed circuit motor not shown. Transistor T1 and resistors R1 and R2 are a common base current source. The current at the collector of T1 is proportional to the current in R1 in the ratio R1/R2. Since the charging current of C is proportional to the motor current which is in turn proportional to deceleration, the voltage across C is proportional to the change in motor velocity. T3 is a unijunction transistor which fires when the voltage across C reaches a predetermined threshold. C discharges through T3 and the base of transistor T4, allowing T4 to conduct. The resulting voltage drop at the collector terminal of T4 can be used to terminate the reverse stopping current in the armature of the motor.

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