Help me out with an automatic fan controller project

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thebadtall

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Hello !
i came up with a great idea, as i was watching the usd/irr charts!
this idea is to make an automatic fan controller, wich consists of a lm317 :grin:
a 2k ntc connected to the heatsink and connected to adj of the ic and a 14v power supply.
for instance at 1892ohm with a 220 ohm adj out resistor it gives 12v out.

will it work? the ntc at normal temperature has 0 ohm? or it is 2k and when it heats reduces?

or i dont need ntc but something else?


also, i would like to use a bc547 or 557 since i got plenty, to turn on at a specific voltage , ie to turn on only between 8 and 9 volts , to warn about high temperature

thank you :-D
 

Re: automatic fan controller

PC Fan Speed Controller - For a Low-Noise PC
**broken link removed**



The thermistor has a rated value of 470 Ω. It sets the output voltage of the LM317T to approximately 7 V at 25 ºC. This should ensure reliable starting of the fan. If the temperature rises to roughly 40°C, the output voltage of the regulator reaches its maximum value and the fan runs at its maximum speed. The voltage drop across the regulator is at least 1.75 V for a motor current of (for example) 300mA, and in any case 2V at the maximum current level of 1 A.
 

thank you !that was my initial idea but i dont know about ntc, wich value should i choose?
 

For post #3 NTC 470R and for post #2 NTC 10K. I also try that circuit from post #2 before several years, and works nice.
 
Aha ! I have received the parts for MrRf's circuit. Except the ntc but I have plenty of dead psu's maybe will fit.maybe not.
Thank you for your info my friend
 

look at my pictures @ some pcb protoboards I make , and then tell me to make it smd!
haha! nice joke! however i wanted a couple of months ago to buy a hot air soldering tool
 

I think to make Fan control sonde small, to be in SMD, I didnt think on some other projects. :wink:

 

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