fan speed controller?

dillemma: i need to control the speed of my fan to lower the noise.

facts: fan- 250cfm, 4" inline blower fan, two wires (pos/neg),4.5amps,12v-dc

power supply-12v-dc, ATX computer power supply.

right now at 250 cfm it sounds like an f'n wind tunnel. i think that i might need a "solid-state speed controller", but i think that is for AC fans???

and i know that a dimmer switch doesnt work....

so basically, what kind of speed controller do i need, and where do i hook it up to my power supply?

edit: i forgot, my ducting is non-insulated alum. flex-duct. im gonna get the insulated kind asap cuz i know that cuts down the sound dramatically. but i still want to slow the fan speed.

go to lowes or home depot. they are like 10 bux. they do have them but don;t put it too slow if you have an a/c hood it will burn and kill your plants. have a thermometer.

but do i need a solid state, or one of the other kinds? all the information that i looked up online said that solid state is for ac, and i have a dc fan....

that dont make sence. you are runing a 250 cfm inline fan that requires 110 volts to run and your running it on a 12 volt adapter. i`m surprised it even runs. that fan should plug straight into the wall thats probably why it`s so noisy, it`s working to hard to run. wire an extention cord to the fan and plug it in the wall. what brand fan is it

actually it does make sense. its a 12volt /dc fan. (not a 110volt ac) thats why its running off a pc power supply. i tried hooking it up to an extension cord, but thats ac voltage not dc voltage.

and its not running hard at all. its just that i want to slow the speed down.
the fan is a "detmar 4" blower fan"
eBay Motors: Marine boat bilge air blower fan 4 inch in line NEW (item 300245002949 end time Aug-01-08 10:18:38 PDT)

thats it.

didn`t even think of a bilge fan. then you can get a 12 volt adapter that has different voltage settings. i do that for my computer fans and works fine.

DC motors (fans) are much easier to control speed. Typical method these days is PWM Pulse width modulation. Fancy term for duty cycle) All it is is turning the fan/motor on for X amount of time and off for Y amount of time.

One could just lower the voltage to the motor, but that will increase the amperage. Not the right way to do it. It works, but can burn out the fan quicker.

Reduce the current to the motor and the motor will get hotter.

Google PWM motor controllers and about a 1000 hits will pop up that will work.

For a cheesy control, use the yellow (12VDC) wire and Red (5 VDC) wires from the ATX PSU. (Yellow being positive and Red used as the neg) That will give you a 7 VDC differential and slow the fan down a bit (30%?) Thats been done a ton, but I've never liked it after dissecting a computer fan. (the hall effect sensor is always trying to get the correct full voltage speed)

mykul916 said:

dillemma: i need to control the speed of my fan to lower the noise.

facts: fan- 250cfm, 4" inline blower fan, two wires (pos/neg),4.5amps,12v-dc

power supply-12v-dc, ATX computer power supply.

right now at 250 cfm it sounds like an f'n wind tunnel. i think that i might need a "solid-state speed controller", but i think that is for AC fans???

and i know that a dimmer switch doesnt work....

so basically, what kind of speed controller do i need, and where do i hook it up to my power supply?

edit: i forgot, my ducting is non-insulated alum. flex-duct. im gonna get the insulated kind asap cuz i know that cuts down the sound dramatically. but i still want to slow the fan speed.

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