Browse Prior Art Database

Variable Frequency Oscillator

IP.com Disclosure Number: IPCOM000074920D
Original Publication Date: 1971-Jun-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 47K

Publishing Venue

IBM

Related People

Cauneille, G: AUTHOR

Abstract

This oscillator delivers approximately 80 mu sec wide pulses, its frequency may be linearly controlled by three logical inputs: START, STOP and SLOW DOWN. It is particularly appropriate for stepping motor control. It is provided with two adjustable speeds, the first is 2000 steps/sec. and the other 300 steps/sec. The slower speed is mainly used during the start operation, it permits starting or stopping in one step. To obtain the faster speed, the frequency is linearly increased during 250 msec. The rise and fall times are both adjustable from 150 to 400 msec and 100 to 500 msec, respectively.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 54% of the total text.

Page 1 of 2

Variable Frequency Oscillator

This oscillator delivers approximately 80 mu sec wide pulses, its frequency may be linearly controlled by three logical inputs: START, STOP and SLOW DOWN. It is particularly appropriate for stepping motor control. It is provided with two adjustable speeds, the first is 2000 steps/sec. and the other 300 steps/sec. The slower speed is mainly used during the start operation, it permits starting or stopping in one step. To obtain the faster speed, the frequency is linearly increased during 250 msec. The rise and fall times are both adjustable from 150 to 400 msec and 100 to 500 msec, respectively.

The STOP input has priority over all other inputs. The SLOW DOWN input is inactive without the START input. The SLOW DOWN input must be energized when it is desired to slow down the stepping motor before stopping completely; this is particularly important since the STOP input suddenly blocks the oscillator without any prior decrease of the frequency. Fig. 2a shows the shape of the frequency vs time curve when various corresponding inputs are applied, as shown in Fig. 2b.

The functional operation of the oscillating circuit is shown in Fig. 1. The circuit comprises mainly an unijunction transistor (UJT) T11 the frequency of which is adjusted by the charge control of capacitor C1. The charge speed of capacitor C1 is controlled by another capacitor C2. The charge of the latter capacitor is linear and allows the frequency to rise and fall. Two trans...