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Square Wave Oscillator Circuit

IP.com Disclosure Number: IPCOM000076834D
Original Publication Date: 1972-Apr-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 24K

Publishing Venue

IBM

Related People

Davidson, JR: AUTHOR [+2]

Abstract

A variable-frequency oscillator, using an adjustable constant current source 11, comprises a transformer having output winding 21 and interconnected windings 19, 20, and a pair of transistors 12, 13. Oscillation occurs due to the positive and negative feedback interconnections of transistors 12, 13 through the transformer, to present a square-wave output across winding 21.

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Square Wave Oscillator Circuit

A variable-frequency oscillator, using an adjustable constant current source 11, comprises a transformer having output winding 21 and interconnected windings 19, 20, and a pair of transistors 12, 13. Oscillation occurs due to the positive and negative feedback interconnections of transistors 12, 13 through the transformer, to present a square-wave output across winding 21.

While transistor 13 is conducting at saturation, transistor 12 is not conducting, since the voltage at the center tap of windings 19, 20 is below the base-emitter voltage needed for conduction. Assume transistor 13 cuts off. The termination of current flow in the right half of winding 19 causes the flux in core 18 to decrease, thereby inducing a voltage in the right half of winding 20. This voltage combined with the supply voltage V of source 11 turns transistor 12 on.

The current flow in collector 24 reduces the current available for the base 26 from source 11. The increase in the collector current and the decrease in the base current continue, until the collector current is saturated and the flux change in core 18 terminates. At this point, the voltage of base 26 drops to about the saturated collector voltage and transistor 12 turns itself off. This causes transistor 13 to turn on in the same manner as transistor 12 was turned on.

The above sequence of operations is repeated and square-wave pulses are generated across output winding 21. The current transfer in a...