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Astable Multivibrator

IP.com Disclosure Number: IPCOM000097687D
Original Publication Date: 1961-Apr-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 25K

Publishing Venue

IBM

Related People

Zvaigzne, G: AUTHOR

Abstract

This transistorized, astable multivibrator is stopped by applying a pulse of proper polarity to the collector of either transistor. Afterwards, astable operation of the multivibrator is restored by applying a suitable pulse to the base of either transistor.

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Astable Multivibrator

This transistorized, astable multivibrator is stopped by applying a pulse of proper polarity to the collector of either transistor. Afterwards, astable operation of the multivibrator is restored by applying a suitable pulse to the base of either transistor.

The multivibrator circuit is the two transistor, collector base coupled type. The initial stable condition for the multivibrator is with transistors 10 and 12 conducting. When a pulse is applied to either base lead 14 or 16, the circuit commences to cycle, in part due to the charging and discharging of capacitors 18 and 20. When a negative pulse is applied to the collector of either transistor, the non-conducting transistor is turned on so that both transistors conduct. Upon release of the collector pulse, both transistors remain conducting and the circuit returns to the initial stable condition and terminates astable operation. In this state, with base voltages at about -.25 volts and collector voltages at about -.15 volts, both junctions of each transistor are forwardly biased. This is a stable situation requiring outside disturbance for return to astable operation.

The same operation is obtained with an astable multivibrator employing NPN transistors. In this case, the polarities of the supplies and input signals are the reverse of those for the PNP multivibrator.

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