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Electromagnet Current Control Circuit

IP.com Disclosure Number: IPCOM000094002D
Original Publication Date: 1966-Apr-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 53K

Publishing Venue

IBM

Related People

Petit, PL: AUTHOR [+2]

Abstract

The bounce of an electromagnet armature is eliminated in applications where mechanical pulse motion is desired by terminating the energizing current at the instant the armature first seals.

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Electromagnet Current Control Circuit

The bounce of an electromagnet armature is eliminated in applications where mechanical pulse motion is desired by terminating the energizing current at the instant the armature first seals.

The usual current waveform in an electromagnet is shown in A1. Current is applied for time t0 causing the armature to first seal at t1. The armature motion is shown in A2 where bounce occurs at t2 and settles at t3 before moving toward rest position at the end of current flow.

By terminating the current at time t1 in B1, armature bounce is eliminated in B2. Thus the start of bounce cooperates to move the armature toward rest position.

The current control circuit shown in C detects current flow at time t1 and cuts off the current supply to electromagnet 3. Circuit 4 is the operating circuit for electromagnet 3. Circuit 5 senses current flow and de-energizes circuit 4 through feedback line 6. An input signal at 7 cuts off transistor T1 via C1 and R1. T2 conducts and unblocks power transistor T3 energizing electromagnet 3.

The variation of current flow through electromagnet 3 is detected by differentiating circuit R2, C3, and R3 and is applied across the differential amplifier formed by transistors T4 and T5. The current retrogression, at time t1 and A1, corresponds to an inversion of the collector voltages of T4 and T5 and is detected by T6. The signal is transmitted through T7 and C4 via line 6 causing T1 to conduct, thus blocking the condu...