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
thanks bavariamotors





RE: 555 timer to vary the pulse with
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
RE: 555 timer to vary the pulse with
http://www.ee.ed.ac.uk/~kap/Hard/555/aplications.html
http://www3.ncsu.edu/ECE480/480_555.htm
etc. for more info