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Transient Detection Circuit

IP.com Disclosure Number: IPCOM000092921D
Original Publication Date: 1967-Mar-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 30K

Publishing Venue

IBM

Related People

Argast, N: AUTHOR [+2]

Abstract

This circuit detects transitory signals. Initially, transistors Q1, Q3, and Q5 are nonconducting while transistors Q2 and Q4 are conducting. However, when a transient signal is applied to the circuit, it switches Q1 on and Q2 off. Positive feedback through resistor R4 aids in the switching of Q1 and Q2. The switching of Q2 off in turn switches Q3 on, Q4 off, and Q5 on, thus lighting light L. Q3 and Q4 form a latch circuit which maintains Q5 conducting after the input pulses subside. Thus light L remains lighted and gives an indication that a transitory pulse has occurred.

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Transient Detection Circuit

This circuit detects transitory signals. Initially, transistors Q1, Q3, and Q5 are nonconducting while transistors Q2 and Q4 are conducting. However, when a transient signal is applied to the circuit, it switches Q1 on and Q2 off. Positive feedback through resistor R4 aids in the switching of Q1 and Q2. The switching of Q2 off in turn switches Q3 on, Q4 off, and Q5 on, thus lighting light L.

Q3 and Q4 form a latch circuit which maintains Q5 conducting after the input pulses subside. Thus light L remains lighted and gives an indication that a transitory pulse has occurred.

To reset the latch, switch SW is closed, thus increasing the voltage level at the emitter of Q1. This sets up a chain reaction in the switching of the transistors which eventually results in the resetting of the latch and the switching of Q5 off. When Q5 turns off, light L goes out. After the transistors are reset, SW is opened and the circuit is ready to detect another transient signal.

The sensitivity of the circuit can be varied by variable resistor R4. The latter controls the amount of positive feedback to Q1.

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