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# Duty Cycle Detector

IP.com Disclosure Number: IPCOM000092925D
Original Publication Date: 1967-Mar-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 28K

IBM

## Related People

Gersbach, JE: AUTHOR

## Abstract

This circuit can be used to control the duty cycle of the input wave. The time constant of the lag caused by R1, R2, and C1, that is, (R1 + R2) x C1, is very much longer than the length of the complete pulse repetition cycle 0 to T2. Therefore, the voltage V1 = (VP - VD1)R2/(R1+R2). Furthermore, the time constant of the lag caused by the combination of R3 and C2, in other words, R3 x C2, is also very much greater than 0 to T2 so that the voltage V2 = (WP - VD2) x T1/T2. Therefore, if V1 equals V2 then T1/T2 = R1/(R1 + R2). This means that, by selecting R1 and R2, the circuit can be used to maintain the length T1 of pulse P at the desired proportion of the total cycle time T2. This can be done by comparing voltages V1 and V2 with null meter M and adjusting the length of pulse P so as to bring M into a null position.

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Duty Cycle Detector

This circuit can be used to control the duty cycle of the input wave. The time constant of the lag caused by R1, R2, and C1, that is, (R1 + R2) x C1, is very much longer than the length of the complete pulse repetition cycle 0 to T2. Therefore, the voltage V1 = (VP - VD1)R2/(R1+R2). Furthermore, the time constant of the lag caused by the combination of R3 and C2, in other words, R3 x C2, is also very much greater than 0 to T2 so that the voltage V2 = (WP - VD2) x T1/T2. Therefore, if V1 equals V2 then T1/T2 = R1/(R1 + R2). This means that, by selecting R1 and R2, the circuit can be used to maintain the length T1 of pulse P at the desired proportion of the total cycle time T2. This can be done by comparing voltages V1 and V2 with null meter M and adjusting the length of pulse P so as to bring M into a null position.

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