DIY Fan speed controller

Ok RIUers.

lets talk fan speed controllers.

anyone know how to make a DIY controller?

I have searched high and low and can not find one anywhere.

AC? DC? brushless?
Done right or just working?

Johnboh said:

Ok RIUers.

lets talk fan speed controllers.

anyone know how to make a DIY controller?

I have searched high and low and can not find one anywhere.

Click to expand...

to go with this fan

http://www.htgsupply.com/viewproduct.asp?productID=52557

just wire a dimmer light switch in between the plug and the fan. Maybe I'll make one of these this weekend and put up a lil diy.

so your saying to get a normal light dimmer switch and splice that in the power cord of the fan.

yup, i would try and make it a bit more professionally/safer than that but thats the basic idea. I was thinking more like wall plug---dimmer----outlet----fan. that way you could plug different devices into it. I'll put a diy if i get some time this weekend.

I would love to see the DIY on this. thanks bro

NO! Do NOT use a standard light dimmer.

At the very least/minimum use a dimmer *meant* for a ceiling fan.

A light dimmer is for a resistive load. A motor is an inductive load.
And even then, its a kludge. AC motor control done *right* is expensive. And the motor should be designed for it.

The 3 speed fans (like a typical box or oscillating fan) is using different coils phased at different angles to achieve the different speeds.

So what do you recommend doing?

Johnboh said:

So what do you recommend doing?

Click to expand...

Ceiling fan dimmer or just get a fan with selectable speeds.

right on. ill get the ceiling fan dimmer. do you know how to wire it up?

Before you do that you may want to check these out. $20 bucks...they are router power tool speed controls. I haven't tried it but have read they work for high velocity can fans and in-line fans. They are rated for 120V and 15A max.

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=43060

Another good call. I've never used one. But have tried a ceiling fan dimmer on a ceiling fan and it didn't work.

I will say that any of these style 'dimmers' will cause the motor to hum some when not at full speed. Just the nature of the beast.

I use S&P TD150. Has two connection. One for High and one for low. I keep it on low and does more then enough cooling a 400W hood.

dutc2006 said:

Before you do that you may want to check these out. $20 bucks...they are router power tool speed controls. I haven't tried it but have read they work for high velocity can fans and in-line fans. They are rated for 120V and 15A max.

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=43060

Click to expand...

Shot, this is a disturbing read for me!

I actually got a buddy to rig up a plug as described earlier --with a regular light dimmer hooked up to the plug and 2 fans plugged in. It was used all last winter but as just turned all the way up throughout summer/fall. I was about to start turning the fan down too. Sounds like I should rethink that huh?

Can it cause a fire or damage to the fan...or both? ...oh well I guess ethier way I better ask my buddy to rewire it back the proper way and spend $20 on one of the dimmers.

If you use a resistive controller meant for lights in essence you will be reducing the voltage to the fan, which reduces the torque the fan's motor can produce. This will reduce the fan's speed but not in the way it was meant to. Proper control of an electric motor should be done with something like square wave oscillation control - i.e. the fan will still receive the maximum working voltage which will produce maximum torque, and by controlling how long it receives this pulse you control the speed.

Again, by using a resistive control meant for controlling incandescent light bulbs you are preventing the fan from getting maximum torque which will technically control the speed but is less efficient and probably harder on the fan. I'm guessing it will work but it's not the best option.

ChemisTree said:

If you use a resistive controller meant for lights in essence you will be reducing the voltage to the fan, which reduces the torque the fan's motor can produce. This will reduce the fan's speed but not in the way it was meant to. Proper control of an electric motor should be done with something like square wave oscillation control - i.e. the fan will still receive the maximum working voltage which will produce maximum torque, and by controlling how long it receives this pulse you control the speed.

Click to expand...

Square wave, aka: PWM or duty cyle works *great* for DC motor but no AC motors.

DC motor control is light years easier to do then AC.

For AC to be done properly, you start with a motor meant & designed for speed control. Aka: Inverter class. With these and a proper inverter, the motor will most likely be triple phase and the inverter will skew the phase angles to control the speed. Most inverts I work with run in the 350-600hz range.


And Like I said before, the fans you buy a a bigbox shop, that speed control is done bu having different filed coils at different angles.

[QOUTE]
Again, by using a resistive control meant for controlling incandescent light bulbs you are preventing the fan from getting maximum torque which will technically control the speed but is less efficient and probably harder on the fan. I'm guessing it will work but it's not the best option.[/QUOTE]

Home Cheapo and such do sell ceiling fan dimmers, guess which dept they are in?

Now, to the OP, why do you need to control the speed of the fan? Why not just get the properly sized/speed fan to start with and forget all this BS?

[/QUOTE]

Now, to the OP, why do you need to control the speed of the fan? Why not just get the properly sized/speed fan to start with and forget all this BS?[/QUOTE]

My setup is pulling air from under the house. In the summer it needs to pull as much as possible to stay cool. But I have found in the winter I really don't need the room as cold as leaving the fan on full allows.

And quite honestly a year ago when installing my current setup my buddy kind of talked me into setting everything up "so crazy". It started out all I wanted was an outlet wired up in a closet....ended up with a outlet wired two different ways, a thermostat for a couple inline 4inch useless duct fans, and two dimmer switches (one for the 4 in cruddy duct fans, and one for the "special" outlet plug for my 6inch inline fan) --I know it's dumb, but I didn't know then...oh well. At least we should have gotten an A+ for effort though, lol

btw - Thanks for sharing the info here guys, it is very educational!

oh yeah, this looks the same as the link above, but is from the HTG Supply store - http://www.htgsupply.com/viewproduct.asp?productID=53142

...next time for me!

Johnboh said:

Ok RIUers.

lets talk fan speed controllers.

anyone know how to make a DIY controller?

I have searched high and low and can not find one anywhere.

Click to expand...

If it's a PC fan, I just started using a universal adapter. Change the voltage and the speed changes.
Inline, that's expensive. I'm low budget.