555 Fan Controller

I recently replaced my hotend with the the E3d. When connecting the cooling fan for the radiator fins to 12v I noticed that my room became significantly louder. I also printed the 80mm MOAB fan bracket to attach a fan and cool the Polyswitch, which I also replaced with a beefier because the previous one was dead. After attaching the 80mm fan to my printer my room sounded like a jet engine was running in it.

So to battle the deafening cooling power I decided to build a Fan controller for both of the fans. At first I was going to just run a Resistor or Diode voltage dropping circuit...But I didn't want to waste electricity to heat and run inefficiently. Also I wanted to be able to control the speed just in case I needed to run it cooler. My next thought was to just use a potentiometer, but this is still inefficient and there is the possibility of overheating if the pot is not rated properly for the load of the fans. So I decided it was time to break out one of my 555 timers I just got. With the 555 you can use a potentiometer to adjust the signal going into it and it can spit out a PWM signal to control the fan speed. I bread boarded many setups and finally found one that worked with parts I had lying around.
Attached are pictures of the setup.

 

Oh the ever useful 555 Timer. Did you know for the first X years they were around they were almost impossible to buy because the US military was snatching them all up to use as the brains in missiles? Interesting little tidbit.

Anyways, love the idea! Where did you get that rad RAMPs fan mount? Mine has only two connection points and is a bitch to position in a way that it doesn't rattle like hell. Any chance you could post the schematic (or even a PCB layout ) for the board?

 

I printed the 80mm fan mount from this link here.

For the Circuit I kinda did a mashup of two circuits to get one that worked for me.
Most of the circuit is based on this.
The idea to use the NPN power transistor was from here.
I tried other ones too but it seemed like I would get one to work and then 5 minutes later it wouldn't.
Below is what I think the schematic is for my circuit. JP1 and JP2 are where the fans connect. R1 was trial an error mainly because of the capacitor I used for C2. That capacitor was the only one I had that would not create terrible harmonics on the fans. C2 is what determines the PWM output range that comes out of Pin 3. This was really fun and frustrating to put together as I have never messed with the 555 before but now that I am getting a feel for what can be done with it I wanna play with them more.

 

the fan on the ed3 needs to run full at all times. My ed3 fan is not that noticeable. I barely hear it. the stepper motors are louder than the fan.

I would suggest also having a fan venting the hot air out underneath the robo. doesn't need to be a big fan. that will help keep the temperature underneath down.

 

Thanks! They really are fun; one of the best experiments to play around with are synthesizers. Look up the schematicfor the Atari Punk Console and mess with it from there. It's a blast.