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My first true electronic project! It's custom fan controller for a hutch with lots of electrical components. I have to leave the door open because it gets so hot. So to fix that, I built this, it uses a attiny85 microcontroller and uses a tmp36 temp sensor, which the microcontroller uses to determine how fast to run fans. It was quite a fun experience! 
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I hope you write this up. I have a similar setup and was thinking us just having the fan running all the time. Maybe I could use this instead. How much did the PCB cost?
+Aaron Newcomb about $5 with free shipping. Component cost was about $5 too. Send me your email over hangouts and I'll send you the eagle cad file and the list of components. For some reason, I'm having trouble programming it. Theres lots of weird bugs going on with the pwm for some reason.
"For some reason, I'm having trouble programming it. Theres lots of weird bugs going on with the pwm for some reason."

Lesson hard learned: get everything 100% debugged and working correctly on the breadboard before ordering PCB.
+Joshua Bardwell I know it's not the pcb. It does the same thing with a simple led on a breadboard. When I analogWrite(0,0) so it's supposed to be off but it's not. It still turns on
I think you're missing my point. The PCB may be fine in this case, but in general, if you order PCBs before getting your circuit and your code 100% debugged, you will get yourself in trouble. Maybe the code worked with an LED, but it's not working with the actual fans, for example. Who knows why? And who knows what changes need to be made to the circuit (and, hence, to the PCB) to fix it?
+Joshua Bardwell I see what you're saying. I did build it on a breadboard before but I didn't test Pwm. Just digitalWrite. I might have to stick to digitalWrite and not Pwm
Aha. So this is more like a "version 2.0" situation ;-)
Seems like this would be a pretty reusable project too.  Share it somewhere maybe so other people can use it as a building block.
+Joshua Bardwell Just a thought, but could it be volt-drop causing your PWM problems? Fan load pulling the input voltage down?
Hi Matt!
We really enjoyed your project and shared it in our weekly "Community Corner" post at Adafruit! http://adafru.it/drq Don't forget to join us for our weekly Adafruit Show and Tell whenever you have a new project to share! http://adafru.it/dfD
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