Hey guys, i have a simple question. I have an Arduino Uno and an old pc fan. The fan needs 12V and 160 mA. I dont now how to output on the Arduino 12V. I want to have the fan on fullspeed so i need 12V. The other question is how i get 160 mA, can i just connect 4 pwm pins together and than to the fan?
No, you can't parallel pins. Just Google "arduino fan" and "arduino motor"
Provide a separate 12V supply for the fan. If you want to control the fan On/Off use a MOSFET to switch the fan power via one of the Arduino GPIOP pins. If you just want the fan on all of the time at 100% just power it separately with the 12V
Even old PC fans tend to be the 3-wire or 4-wire brushless types. They will perform very badly if you try to PWM the power. But they work quite well if you connect their control wire to an Arduino PWM pin and give them a clean 12V supply from an external source.
Always connect the grounds.
You could use a transistor like in the link below. Shows how to use it with an Arduino.