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Browse Prior Art Database

Self Biasing Oscillator

IP.com Disclosure Number: IPCOM000097556D
Original Publication Date: 1961-Feb-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 29K

Publishing Venue

IBM

Related People

Dorrell, CE: AUTHOR

Abstract

The circuit shows a simple oscillator which has been altered by using a third transformer winding and a rectifier to establish its own D. C. bias.

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Self Biasing Oscillator

The circuit shows a simple oscillator which has been altered by using a third transformer winding and a rectifier to establish its own D. C. bias.

Initially, the base of transistor T is at some voltage more negative than +V but more positive than ground. Since the emitter of T is grounded, it is cut off. A negative trigger pulse applied to T's base causes it to conduct and oscillations of the circuit begin. Winding 2 of the three winding transformer provides the necessary positive feedback to sustain the oscillations.

Winding 3 and diode D1 provide the source of constant negative bias to maintain T in a conductive state. Diode D1 becomes conductive only on negative excursions of voltage in winding 3. Due to this extra negative voltage produced by the rectification process, the base of T becomes more negative than ground and conduction is sustained in T. A positive pulse applied to the base circuit cuts off the transistor, eliminating all sources of feedback and bias potential.

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