Hi new here if I don't know how to procedure I do apolidise
I would like to know if anybody could help me how could I control the duty cycle of a pmw modulator (555 Ic for instance) by temperature with a ntc
Thermistor
thank you
Marcus

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There are a number of example circuits on the web such as this one.

I bit of googling can uncover quite a few 555 based PWM controllers with temperature control.

Of course, some alterations will be needed to get the functionality consistent with your application.

hgmjr

 

yes I have seen those circuits on the net as a matter of fact the one I am using is similar to the one you point me to I was think of a circuit that would uses two transistor (NPN & PNP) instead of those two diodes and the 100 kΩ pot please see atachment . Than control the base of the two transistor with the thermistor that way I would not change the frequency. only the duty cycle
but I don't have the enough knoledge to design the circuit
Thank you for your interest I really appreciate
Marcus