Need some help RE fan controllers

wild thing

wild thing

wild thing

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Hi,

Im looking for some advice from knowledgable folks regarding a fan controller for high current fans.

I have an unusual modification in mind to what is probably normally discussed on this forum. I have a wetsuit hanger by a company called Underwater Kinetics (Hangair drying system) that basically uses a 120mm computer fan to blow air through the suit for quicker drying. http://www.uwkinetics.com/products/hangair-drying-system

I'm thinking of upgrading the cheap stock 120 cfm fan with a San Ace 9SG1212P1G01 that pushes 260 cfm. That fan is rated 48W and 4A. I have purchased a 12V 5A dc powersuplly to handle the extra power needed, however i was hoping to be able to control the fans speed because it'll be fricking loud and I won't always want it running full power.

Does anybody know of any speed controllers out there that can be bought off the shelf that can handle a 4A - 50 watt fan? something in a small neat package with control knob would be ideal, I'm not knowledgable enough to DIY my own...

There is a post here showing the hanger in a bit more detail: http://www.tribalsurf.net/viewtopic.php?f=12&t=1412
 
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Ok, so i have been searching a solution to this and have learned a little more.

The only product i have found for this task (on the computer market) is sold by a US company called sidewinder computers, they call it the Sidewinder 50 Watt Rheostat.

A closer look at their picture reveals that the product is an OHMITE RSJ35RE (50W~35 ohm) Rheostat, they simply solder on some sheathed cables and connectors, and apply heat shrink. They're quite difficult to source here in the UK for good price, but i have found a company that sells them and if you buy 2 or more the order qualifies for free shipping otherwise they add an additional £11 for delivery for just 1 item (ouch)

http://uk.mouser.com/Passive-Components/Resistors/PotentiometersTrimmers-Rheostats/Rheostats/_/N-8m03f?P=1z0x6i4Z1z0vl7s&Keyword=Passive+Components+Potentiometers+Rheostats+Rheostats&FS=True

They charge £27 each but everywhere else is asking around £40+ each. I've had a search on ebay and someone in Hong Kong sells similar rheostats for a lot less but I don't think their in the same class as OHMITE are apparantly made to military spec....

Anyway, just thought I'd share what i've learned and the conclusion is that if you want control a high speed Delta (PFB1212UHE) or San ace (9SG1212G101) or similar fans, then you need an OHMITE RSJ35RE rheostat (50W~35ohm) AFAIK.

Hope that helps other folks in this situation.

* Edit *

Read below ↓
 
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Tealc said:
A MOSFET and 555 based fan controller circuit would be much cheaper. Haven't experimented with high current DC control but an IRF510 can sink 5.6A.

From memory you'd need a basic £1 potentiometer, a 10p 555 IC, a breadboard or prototype board, some wire, and some basic passive components. The losses from PWM circuits are minimal too, whereas the rheostat you have chosen would get super hot.
Click to expand...

Would you be able to put one together for me?
 
Hi, its up to you. If you feel competant enough to build one for me and it'll work like a charm and be reasonably inexpensive, then i'd be willing to pay you for your troubles. I know **** all about electronics, circuit boards, IC's etc etc.

I don't have a fan either at the moment, struggling to find a source for fans of that calibre available in the UK (Delta, San ace, Nidec servo) they're all US products and rare over there as well.
 
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Well thats terrific guys, I'll order that part then and also a project box to mount it in.

You've saved me a fair bit of money there over ordering 2 of those Ohmites, thanks very much for your advice, appreciate it.

If anyone knows where i can get hold of one of those high power Delta / San ace / Nidec Servo's in the UK for a good price it'd be terrific.

:)
 
Hey guys, I asked customer support at sidewinder computers about controlling those fans and gave a link to that PWM motor controller.

The response I got was

Is it 12v to 40v adjustable? If so, it could simply blow the fan if you turn it above the lowest setting as you will feed more voltage in than it is capable at running. You need one that is either 5-13 or 7-13v DC and with that amperage capability.
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My response:

yeah, 12v~40v. Im not sure if it makes a difference but I will be using a 12V 5A (60W) DC power adapter as power source. surely that electronic motor controller can only output the maximum voltage that is fead into it?

I pressumed that the voltage rating and the amperage rating (10A) were just specification of what that component can handle being input into it.

Does that make sense?

His response (lol)

Usually Delta fans have overvoltage protection. That is not something I have tested to see if it works or not though.
Hard to tell what this thing can do. The specs are not clear. It takes 0.02 amps on standby (is that at the lowest setting or is it with nothing connected?)
Control power is 0.01 to 400W, I'm guessing that 0.01 W is at 12v DC, and max output 400W at 40V DC, which would be 10 amps, so that is correct, using the typical Watts = Amps x Volts formula.
Click to expand...

Naturally im more confused than anything now. Is he right that I need one that ranges between 5v ~ 13V? I figured the important specs are the "duty cycle" and "PWM frequency" that determine the control ability. I've read up a little on PWM and thought the major factor of PWM control was that it monitors the fans rotation speed and delays the interval of 12V power put into it dependant on chosen speed setting to maintain that speed, but to the fan it looks like a lower voltage but it is in fact 12V.

Is that right? is he wrong? am I wrong? who's right?
 
Yeah, i suspected he was getting PWM speed control mixed up with non PWM method of controlling speed.

I take it that using a PWM controllable fan a neccessity now using that controller....
 
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