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Filter Circuit

IP.com Disclosure Number: IPCOM000095417D
Original Publication Date: 1964-Jan-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

Harrison, TJ: AUTHOR [+2]

Abstract

The filter has a relatively long time constant as compared to the usual RC filters. Such is without degradation of the common mode rejection

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Filter Circuit

The filter has a relatively long time constant as compared to the usual RC filters. Such is without degradation of the common mode rejection

The signals to be transmitted are applied to input terminals 6 and 7. At the same time, single-shot multivibrator 40 is pulsed. This, through relay 44, closes switches 45 and 46, respectively, in the transmission path of the input signals. Capacitor 18 rapidly changes due to its relatively small time constant. After cutoff of single-shot 40, relay 44 drops out and switches 45 and 46 open. The input signals are now applied to chopper contacts 14 and 15. With the associated contacts blades 10 and 11 closed simultaneously, the signals are transferred to condenser 9 of a low capacity for intermediate storage. Then, blades 10 and 11 transfer so that the condenser 18 can be charged through chopper contacts 16 and 17 by condenser 9. Condenser 18 is connected in parallel to filter resistor 21 and to output terminals 19 and 20. This cycle is repeated at the rate of the chopper frequency.

The arrangement permits the construction of RC filters of large time constants, which can be varied by varying the chopper frequency. The rapid charging of condenser 18 caused by the single-shot 40, when turned on at the start, largely avoids the effects of transients.

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