# Pulse width duration?

Discussion in 'Homework Help' started by pfelectronicstech, Aug 25, 2012.

1. ### pfelectronicstech Thread Starter Member

Jan 18, 2012
178
4
I do NOT want the answer, I just want to be pointed in the right direction. Its a 500-HZ digital signal and duty cycle is 20%. What is the formula, or how do I get to the answer because I can't find it in my book? Thanks for the help again.

2. ### Jony130 AAC Fanatic!

Feb 17, 2009
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D = Ton/( Ton + Toff)

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3. ### bertus Administrator

Apr 5, 2008
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pfelectronicstech and absf like this.
4. ### cork_ie Member

Oct 8, 2011
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This NE555 PWM calculator should be of help

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5. ### pfelectronicstech Thread Starter Member

Jan 18, 2012
178
4
Thanks guys, I'm not fully understanding yet, and I'm not sure why. I'm gonna give it one last look in my books, and move on. Thanks again.

6. ### Jony130 AAC Fanatic!

Feb 17, 2009
3,990
1,115
The answer is quite simple.
For F = 500Hz and D = 20% we have
T = 1/F = 1/500 = 2ms
D = Ton/T * 100%
Ton = (D * T)/100% = (20 * 2ms)/100 = 400us

7. ### pfelectronicstech Thread Starter Member

Jan 18, 2012
178
4
I got it now, thanks guys. It all came together in the end. Thanks again for the help.