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555 timer to vary the pulse with

555 timer to vary the pulse with

555 timer to vary the pulse with

(OP)
i want to use a 555 timer with a oscalating but variable input,and the same time to control the with of the output pulse via a variable voltage,ither the pin 5 to control the pulse with/or how ever?
thanks bavariamotors

RE: 555 timer to vary the pulse with

bavariamotors,

What you're looking for is a pulse width modulator.  This can be achieved by configuring the 555 as a "one shot" monostable circuit with the reset node driven by the signal you want modulated.  If a phase lock on the incoming signal is desired, adding a 2-input NAND gate and flip-flop between the 555 output and the reset lines can achieve this.

An example of such a circuit can be seen at:
http://www.osee.net/whitepapers/paper123.pdf

Varying the 555's output pulse width is achieved through its (R1 + R2)*C timing constant, which is defined in the 555 technical data sheets.  See http://www.ti.com for a copy of the 555 data sheet.

Enjoy.

-- Warpdrive

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