How do you drop a 14 volt DC source to a lower voltage?

This is for a fan inside my older stereo that I just replaced. It is quite loud and irritating spinning as fast as it does. I previously ran a 12 volt DC fan off of a 4.5 volt DC source and it was quieter and slower. So how can I lower the 14 volt DC?

appolo8 years ago
A LM317 adjustable type regulator could be used, the data sheet shows example circuits. However as orksecurity says you may compromise cooling at a slower speed!
jmscfrk (author)  appolo8 years ago
as I said to orksecurity, the fan just won't work at lower voltages so I'm just ordering a slower one/quieter one, pretty sure I don't need a 2500RPM fan in my stereo! Thanks for your help
orksecurity8 years ago
A suitable resistor would work, but would waste energy. (Exact value depends on the impedence of the fan.) A more efficient solution would be to run the 14VDC into a voltage regulator circuit that outputs 12VDC; that's usually one chip and a few passive components. A more elegant solution would be to get a quieter fan, which would avoid losing airflow when you reduce the speed.
jmscfrk (author)  orksecurity8 years ago
Thanks, the ampere is .16 and the wattage is 1.9 I already experimented with resistors, and got the voltage down to 10-11VDC I think? Well anyways, I tried lowering more and it just stopped spinning. Found out the range is 10.8VDC to 13.8VDC, its a 2500RPM pancake fan, so I'm just getting a slower fan through my work catalogue. All very frustrating, 17.88 for the fan and 26 some-odd for the soldering iron and resistors! Total waste of my money. Thanks for the advice though!