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Variable Frequency Sawtooth Generator

IP.com Disclosure Number: IPCOM000097278D
Original Publication Date: 1962-Aug-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 42K

Publishing Venue

IBM

Related People

Fiorino, BC: AUTHOR [+2]

Abstract

This generator supplies a sawtooth wave whose amplitude is maintained constant, independent of the repetition rate which varies in accordance with a variable input voltage.

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Variable Frequency Sawtooth Generator

This generator supplies a sawtooth wave whose amplitude is maintained constant, independent of the repetition rate which varies in accordance with a variable input voltage.

It includes a constant current source, transistor 1, having a variable D.C. input voltage connected to its base to control the charging current from 1 to timing capacitor 2. When the voltage across capacitor 2 reaches a predetermined level, +3V, the current conduction is switched from transistor 3 to transistor 4. This switching in turn switches current conduction from transistor 5 to transistor 6. Transistor 7 is then turned on, thus discharging capacitor 2. The voltage across capacitor 2 discharges toward -6V. However, at -3V transistor 8 provides a clamp. At this point the collector of 8 goes slightly negative and this switches the conducting condition of switching transistors 3-4 and 5-6. Transistor 7 is turned off and capacitor 2 begins again to charge toward +3V.

The frequency of oscillation of the circuit is varied by changing the current delivered by transistor 1 by changing the D. C. input voltage at the base of 1. In response to a start input, transistor 10 clamps capacitor 2 at ground potential and starts the sawtooth wave form at the zero voltage. The amplitude of the sawtooth wave is maintained constant and the sawtooth wave output passes through zero potential at exactly the half period point.

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