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Blocking Oscillator With Stabilized Pulse Duration

IP.com Disclosure Number: IPCOM000096383D
Original Publication Date: 1963-Apr-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 22K

Publishing Venue

IBM

Related People

Frantz, H: AUTHOR

Abstract

The pulses generated by this blocking oscillator circuit are largely independent of transistor deviations, variations in the operating voltage and changes in the load. The fundamental requirement of such a circuit is that the curve of the feedback voltage and of the resulting base control current, respectively, exhibit a maximum steepness at the moment of cutoff.

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Blocking Oscillator With Stabilized Pulse Duration

The pulses generated by this blocking oscillator circuit are largely independent of transistor deviations, variations in the operating voltage and changes in the load. The fundamental requirement of such a circuit is that the curve of the feedback voltage and of the resulting base control current, respectively, exhibit a maximum steepness at the moment of cutoff.

The blocking oscillator consists of transistor T and the feedback transformer with windings W1 and W2. Connected in parallel to the feedback winding W2 is the series arrangement of a resistor R and a condenser C. The common junction of the two is connected to the emitter potential. Tap 1 of winding W2 connects to the base of T.

If T is rendered conductive by an input pulse, the feedback process is initiated through windings W1 and W2. The voltage effecting the feedback action is Ube = U12 - Ur. The curve of the voltage Ube is determined by the circuit constants of R and C and follows an e-function. By suitably selecting R and C it is possible to achieve a maximum steepness of this voltage curve at the moment of cutoff.

The right-hand drawing is a plot of the feedback voltage Ube with respect to time. It starts at values effecting a high feedback and, after an interval t1, crosses the value Ube min with the desired degree of steepness, starting at which point T is cut off.

Condenser C can be replaced with an inductance resulting in a corresponding effect....