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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A MOSFET and 555 based fan controller circuit would be much cheaper. Haven't experimented with high current PWM 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.
 
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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?
 
Possibly but I don't have a fan (or much else) with that sort of current to test it with.

This is the sort of thing I mean.

pwmfancontrollerwith555.jpg


The 555 circuit sends a signal to the mosfet to open and close according to the resistance and capacitiance on the left of the diagram.

I've experimented with this design on some standard current fans and it's behaved quite well.
 
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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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I think that'd do the trick.

10 Amps is clearly enough and it works with 12v.

There seems to be three mosfets to share the load and each are well heatsunk.

I'd go for that and for £6 I don't think I could get much cheaper if I made one for you.

Looking at the circuit on there it's probably very similar to the circuit I displayed above with it's 8 pin dip IC (the famous 555 timer IC), a couple of fast switching diodes (the little red things), one or two passive resistors (blue things with stripes), a potentiometer (with the big knob on it) and the mosfets (black casing with three legs) attached to the heatsink. The 1000uF capacitors will help to remove PWM growl too.
 
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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.
Click to expand...

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?
 
The 40V probably relates to the maximum voltage permissable through the timer IC. It may be a LM122 which is good for 40V rather than the NE555 I thought it might be as that has a much lower voltage capability.

PWM doesn't work by varying the voltage to the fan as such, it's basically an on-off state with varying degrees of on compared with off. The speed at which a full cycle occurs can be very fast.

From what I can see this controller board does not regulate voltage so if you feed it 12v it'll produce 12v. I think your guy might be confusing it will a DC regulated fan controller, which this isn't.

So in summary, that controller is perfect for what you need. Please trust me on this. I know a bit about this PWM circuits having built several and while I'm not an expert in electronics I can still be confident about this.
 
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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....
 
wild thing said:
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....
Click to expand...

No. The FET normally found in PWM fans is in the circuit already so it's not needed on the fan. Using this sort of circuit I managed to control a 2 pin ex-PSU fan without issues. This PWM controller carries out both aspects of PWM generation and switching.

wild thing said:
Does the length of cable from controller to fan affect operation? I was thing thinking of using a long length say 10ft?
Click to expand...

Not really. You'll get a small voltage drop due to the length but that's nothing to worry about. You'll need to make sure it's reasonably thick cable though for 5 Amps.
 
You are correct and i would agree with Tealc, again i am no expert but if you use 12V 5A dc powersupply you will be fine, it does not regulate volts, PMW switches on and off, the longer on periods the faster the fan & Vice versa, i.e 100% duty cycle full fan RPM,the unit will control any fan within the voltage range of the controller with the correct powersupply & fan,your man at sidewinder computers is confused.
 
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