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help me correct a pwm circuit replacing a pot with ntc

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thebadtall

thebadtall

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Hello, i would like to use this circuit
**broken link removed**

and replace the potentiometer with a ntc, because all i want is auto-throttle using pwm.

however, the ntc drops restistance as heat increases, and so, i am not sure how i can reverse that.

can you suggest a fast sollution ?

probably i need a completely different configuration right ?

thank you
 
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Pin 5 provides a method of adjusting duty cycle from the 555. If you want your NTC sensor to reduce duty cycle as it heats up, then it can go in the bottom half of a resistive divider.



Of course you would need to tailor-adjust values in order to get your desired range of operation.
 

I want the opposite, duty cycle to be increased as heat increases.
I thought of using ptc but I only have a couple ntc's available
 

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