555 timer to vary the pulse with

[bavariamotors]

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

 

[Warpdrive]

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

 

[jbartos]

Suggestion: Visit

http://www.ee.ed.ac.uk/~kap/Hard/555/aplications.html

http://www3.ncsu.edu/ECE480/480_555.htm

etc. for more info