How to power multiple devices

Hey guys,

So I’m looking to build a temperature controlled fan with a potentiometer and led display so that I can set the threshold temperature for when the fan turns on.

In my circuit right now, I have:
1 potentiometer
1 4x4 7 digit LED display
1 TMP36
1 TIP 120
1 PC Fan (it can be any voltage that will work with the rest of the circuit)

My question is if I can power this all through my Arduino Uno connected to a wall-wart. I haven’t purchased any supplies yet, so I can get a certain voltage power pack and fan if that’s necessary. I attached a fritzing diagram of the circuit I currently have planned out.

Thanks for any help!

BBQFanPlugInNew.fzz (6.92 KB)

BBQFanPlugInNew_bb.pdf (831 KB)

I attached a fritzing diagram of the circuit I currently have planned out.

That diode looks wrong, it should be across the motor not the transistor. I hope you don't actually make it on a solderless bread board they are notoriously unreliable.
In theory that should work but there might be interference from the motor causing the arduino to randomly reset. You need to apply some hefty decoupling of the supply with motors.

That diode looks wrong, it should be across the motor not the transistor. I hope you don't actually make it on a solderless bread board they are notoriously unreliable.

Yeah I accidentally uploaded a slightly older version, I meant to have the diode across the motor. And I just use breadboards to help me visualize the circuit (I'm a Computer Science guy so I'm not quite as good with the electrical side of things), I do plan on actually soldering the whole circuit once I get it working.

In theory that should work but there might be interference from the motor causing the arduino to randomly reset. You need to apply some hefty decoupling of the supply with motors.

So would a 12V decoupling capacitor in between the arduino and the motor be enough?

Thanks for helping out!

Yeah I accidentally uploaded a slightly older version, I meant to have the diode across the motor. And I just use breadboards to help me visualize the circuit (I'm a Computer Science guy so I'm not quite as good with the electrical side of things), I do plan on actually soldering the whole circuit once I get it working.

By all means try and start to learn to 'visualize' the circuit by reading the schematic drawing, everything is there every connection and every component. Then move on to breadboarding only to actual build the circuit for testing and validation before committing to a soldered version or developing a PCB.

Your approach will slow yourself down vastly as you move on to more complex circuitry.

try and start to learn to 'visualize' the circuit by reading the schematic drawing, everything is there every connection and every component.

I appreciate the feedback, its definitely something I'll start learning. Do you have any recommendations on how to decouple the motor from the power supply?

So would a 12V decoupling capacitor in between the arduino and the motor be enough?

Sorry a bit of a silly statement. The voltage rating of a capacitor is simply the voltage you must not exceed. So for a 12V circuit you could use any capacitor voltage rating of 16V or over. ( 12V rating capacitors do not exist )
What you mean is capacitor value it need to be determined by experement but basically a 0.1uF ceramic capacitor in parallel with a much bigger one say 47uF or bigger.

Do you have any recommendations on how to decouple the motor from the power supply?

Last circuit on the page.
http://www.thebox.myzen.co.uk/Tutorial/De-coupling.html

Thanks! This helped me understand what and why I need to do.