Since there's no "hardware infirmary", I'm here...

[the gnome]

This dude knows what's up.

Variacs are the way to go. I have two of them and they run wonderfully. I think they were ~$70 shipped. They are pretty heavy, but as Boris says, the weight is a sign of reliability. The ones I have are adjustable from 0-150 volts. So I could actually overdrive my fans if I wanted to, although I probably never would do that for safety reasons.

where are you finding the $73 variacs?


they offer this on the can fan site
http://canfilters.com/accessories.html
is this a variac?

 

[944s2]

One month along and all systems function perfectly. The ballasts are handling switching between output levels, timer changes and random operation. The HydroStar Pro is functioning perfectly and is ideally suited for noise and heat free operation.

hiya,,grobot,,thanks for taking the time to post your findings,different names/brands for speed controllers etc in the uk but problems like you addressed can effect all of us,just want say that your posts/work is appreciated,nice one,,,,,peace and regards s2

 

[growshopfrank]

where are you finding the $73 variacs?


they offer this on the can fan site
http://canfilters.com/accessories.html
is this a variac?

here is one for $50
http://www.amazon.com/Variac-Variable-Transformer-300va-Output/dp/B006NGI8VS

 

[ak-51]

where are you finding the $73 variacs?


they offer this on the can fan site
http://canfilters.com/accessories.html
is this a variac?

http://www.frys.com/product/4638758?source=googleps&gclid=CMzshPn2tbICFdNxMgodMkoACA

That looks exactly like the ones I have, but I could swear I was getting mine for about $65-70 including shipping. I can't remember where I bought mine from.

 

[the gnome]

the amount of amps it goes up to seems to affect price looking at GSF's amazon link.
i have a 12" max fan and a reg speedster produces a lot of humming when you lower it, i don't think its too good for my fan motor.
the one in my link for $250ish is recommended for that fan.

and check this out.. looking on e how on variacs they say not to use it to control fan speed??

 

[rives]

and check this out.. looking on e how on variacs they say not to use it to control fan speed??

Bingo. The only reason that variacs work reasonably well with fans is because the motor is placed in the airstream. As a result, they get far more cooling than a motor in another application. Motors are very sensitive to voltage reduction - as the voltage goes down, the current (amperage) goes up. They also lose torque very quickly, and if the motor torque goes down but the load remains remains reasonably static.......the current goes up. The only really good way to control motor speed is via changing the frequency, but variable frequency drives are very expensive and it is difficult to find products for single-phase, 120v motors (as far as I know, there is only one manufacturer of them).

I recently bought a Fantech FG-6M-EC, which uses a different technology motor with integral speed control. They use inherently less current, and have a broader usable speed range than anything else that I have found. They use a 0-10vdc input for speed control, and I am going to hook mine up to a PID loop temperature controller. Should be interesting.

http://fantech.net/download/FG-EC-Brochure