amperage question

Jeremy, You should be able to run it OK. The voltage in your truck will be closer to 13.8V when running, and nearer to 12.5V when off. Most 12Vdc fans can operate at these slightly higher voltages without a problem. To be absolutely sure, you can check the manufacturer's specs. If you don't know how to do that, post the manufacturer and part number here, and someone here will look it up and let you know for sure. The manufacturer and part number are located on the label in the center of the fan motor.

As long as your truck is 12 Volts.

CPU fan can work from as low as 8 volts, so a few volts above 12 v can be too much. I would definitely stick a voltage regulator.

(+) ------- [7812] ---------+ | | | [FAN] | | (-) -----------+------------+

The 7812 needs 14 to 15 volts on the input to regulate.

Well, it works for me in practice. See for yourself:

The regulator is obviously not regulating, in your photos. He could accomplish the same thing a whole lot cheaper with a resistor or three diodes.

Ed

If the voltage is less then 12 volts out then the 7812 is simply a resistor dropping the voltage. Why even use it in the first place?

It will be happy there...

I'd also, on the off-chance that's it a brushless DC motor, put about a transzorb across the input, like a 16V or so, and probably a hash choke (that's just an inductor that can handle the DC current without saturating.)

Automotive electric systems are hell on electronics.

Good Luck! Rich

Because when the voltage goes much above 12V, the regulator will go into regulate-mode and protect the fan.

Mark