The Whitaker Corporation

Cts Corporation

Raymond M Carlisle

James Michael Raudenbush

Steven J Fry

David Francis Fleming

An oscillator assembly has a voltage controlled crystal oscillator that produces a stable reference frequency. The voltage controlled crystal oscillator is connected to an electronic frequency adjust voltage. A temperature compensation circuit is connected to the voltage controlled crystal oscillator. The temperature compensation circuit provides a temperature compensation voltage to the voltage controlled crystal oscillator. A trim effect compensation circuit is connected between the temperature compensation circuit and the electronic frequency adjust voltage. The trim effect compensation circuit adjusts the temperature compensation voltage in response to a change in the electronic frequency adjust voltage.

Trim effect compensation circuit

A cable length indicating arrangement which utilizes the capacitance of a two wire cable (10) to determine its length. The arrangement includes an oscillator stage (14) having a frequency setting capacitor (16) across which the cable is connected. The frequency of oscillation is converted into a voltage which is provided as the input to a comparator network (70, 72, 74, 76, 78, 80) which compares this voltage against voltages derived from a voltage divider network (96, 98, 100, 102, 104, 106, 108). The comparator network includes a 'ladder' of comparators each having their non-inverting inputs coupled to receive the frequency dependent voltage and their inverting inputs each connected to a respective point in a resistive divider string. The outputs of the comparators are connected to respective light emitting diodes (82, 84, 86, 88, 90, 92). As the length of the cable is increased and its capacitance increases, the frequency of oscillation decreases, the frequency dependent voltage decreases, and the light emitting diodes are energized one by one, to provide a bar graph display indicative of cable length.

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Loysville, PA, United States of America

Raymond M Carlisle