Stir plate fan speed controller???

I have a 12v power supply, my fan is 12v and I got a 10ohm potentiometer. I am doubting my choice in 10 ohm... Is that high enough or should I get a rheostat that goes up to 100 ohm? I wanna do this the cheapest most efficient way possible... Suggestions from the experienced people would be appreciated


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http://www.amazon.com/dp/B00080G0BK/?tag=skimlinks_replacement-20

this was the best deal i could get, works like a champ. I think many on here use it as well.

That Is a fan, I have 2 fans, I just need info on the rheostat or what speed control I need to use


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Consider a 12v led dimmer module. These can be found on eBay for buttons (~$2-$3) and use PWM - very effective for motor speed control.

EDIT: Link -

http://www.ebay.com/itm/DC12V-24V-8...ing_Parts_and_Accessories&hash=item43c36500e6

Is there a certin one you would recommend? A link perhaps?


There it is thanks!!!

Realised this afterwards and edited my post - moments too late it would seem !

It's all good, how would I fit this in a project box? I may need to get a larger box possible if it goes in straight up


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GeorgiaMead said:

It's all good, how would I fit this in a project box? I may need to get a larger box possible if it goes in straight up


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Click to expand...

There is just a single board inside these with some wires to the knob on the front - the box they come in exaggerates the size of them greatly. See the thread below for shots of the internals: but pay no attention to the modifications they are making - they do not apply in this circumstance. Since the knob is connected via wires this should give you flexibility in how to squeeze it into another box.

https://www.homebrewtalk.com/f170/slow-pwm-using-hacked-led-dimmer-432147/

Fantastic sir! So just cut the board off or just run the board in the box? I'm new to this type of electrical work. I'm very able to do most other stuff... Sorry for all the noob questions


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I disassembled mine and took some photos for you.

This is the complete unit. The knob literally pulls off and there is a nut underneath to undo that holds the workings underneath in place. There are also 4 screws on the face of the device to remove.


This reveals the internals - and the knob should now also be free of the front cover of the device. Now the external green wire terminal just pull out again - literally just pull out and the board itself is held by two screws that need removed.



What you are left with is the actual parts you need that are at the bottom of this image and a knob as well. Everything else has little purpose. To mount the knob, all you have to do is drill a hole in your box to accept the it and use the nut taken off earlier to secure it in place.

Thank you! Once mine come in, in a few weeks I'll prob be asking more noob questions


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I just built a stir plate. I was able to get a free cigar box at a local smoke shop and it worked out perfect. Here is where I got most of my information for the build.
http://www.wortomatic.com/articles/Building-a-Basic-Stirplate-for-Yeast-Suspension

One thing that I noticed in your information was that you have a 12v power supply. In my reading that is way too much. I used an old 5.9v phone charger and it worked perfect. I only use about 20% of full power before it spins the weigh off. I used a 3watt 25ohm rheostat to control it and a 12volt fan that I took out of an old computer, along with the hard drive magnets. People were saying with a 12v power supply it was burning out the fan and making the rheostat heat up. Maybe I'm misunderstanding your question.




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So if I doubled to a 50ohm rheostat 6 watts that should cover the power correct?


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I have ordered rare earth mag. That I will be gluing to the fan, the hard drive magnet is small and will throw the bar even on the slowest speed I can obtain... So I may just make 2 of them... As I will have plenty of stuff to make multiple ones


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GeorgiaMead said:

So if I doubled to a 50ohm rheostat 6 watts that should cover the power correct?


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Click to expand...

Looks like it should work to me. I'm no electrical engineer but that makes sense. Good luck!


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I'll ask a relative who actually is an electrical engineer... See if he can give me the most efficient and effective way to do this...


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For attaching the magnets, you might also want to try gluing a metal washer to the fan and then the magnets just hold themselves onto that. It gives you flexibility in the number and placement of the magnets - tweaking this can have a big effect on the stir bar being thrown. Some smaller fans might not cope with the extra weight, though, so trial it first if you decide to go with this approach.

You certainly can use resistance or reduce the voltage to the motor to reduce its speed and the majority of people do do that. But PWM is a better solution. If you already have the parts to go with the resistance method then use that by all means. But if you haven't purchased anything yet then the dimmer module is only a slight increase in cost and you get a ready-to-go system - screw terminals for two wires in and two wires out - no soldering, no wiring diagrams etc ...

The problem is that most people still percieve PWM as being a complex or expensive thing to achieve. These cheap chinese LED dimmer units throw that right out the window at a few dollars a piece - I paid £1.89 for mine ($3.15). You will struggle to get a large capacity potentiometer/rheostat for much less than that.

I could not agree more with the previous speaker. The LED dimmers are awesome for this. And the PWM control in addition to being more effective, will allow you to run the fans at lower RPMs before stalling.
They are so cheap, that I ordered a bunch of these and use them to control pumps and with some modification SSRs. They are grrrreat!

Well I have ordered one, so a couple weeks till it arrives


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Thanks for the idea on the PWM dimmer module, just ordered one from amazon for my stir plate build, $5 CDN. Been searching all over for something a little more electrically sound than a Pot wired in series.

Hi
Here is my cheap & dirty stir plate version. I had the 5" computer fan, the hard drive magnets and the 12v power supply. Used 2 1/2 bolts with nuts for legs, fan already had pre-drilled holes in each corner. Glued a piece of plastic on one side in order to mount the potentiometer. Didn't really see the need for a project box as the little screws on the fan top allowed for adjustment height of the flask. Works like a charm
Jim

kayakman said:

Hi
Here is my cheap & dirty stir plate version. I had the 5" computer fan, the hard drive magnets and the 12v power supply. Used 2 1/2 bolts with nuts for legs, fan already had pre-drilled holes in each corner. Glued a piece of plastic on one side in order to mount the potentiometer. Didn't really see the need for a project box as the little screws on the fan top allowed for adjustment height of the flask. Works like a charm
Jim

Click to expand...

If you don't want it to slide off some day, put something anti-slip on the top of the fan, at least in the corners where the flask rests.

I am putting my stir plate together finally... With this dimmer is it possible to hook up a toggle switch for power with this setup? There are four slots [-][+][+][-] In and out and I can't get it to adjust speed with out running power directly in the dimmer any diagrams or pictures to help please?


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I'm at soccer practice and it hit me what if I run power to thru te dimmer and put the power between the dimmer and the fan?


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See below: The switch could go on either the positive or negative wire, FYI.

Thank you! Just wasn't clicking kinda brain dead... Makes perfect sense now I feel dumb

thanks for the help!


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kayakman said:

Hi
Here is my cheap & dirty stir plate version. I had the 5" computer fan, the hard drive magnets and the 12v power supply. Used 2 1/2 bolts with nuts for legs, fan already had pre-drilled holes in each corner. Glued a piece of plastic on one side in order to mount the potentiometer. Didn't really see the need for a project box as the little screws on the fan top allowed for adjustment height of the flask. Works like a charm
Jim

Click to expand...

What kind of flask is that? It looks um, "squatier" than normal. Love the stirplate, btw.

Here's my beast, I'll be using it this weekend for my first AG batch. The LED light dimmer worked great. Don't know if it's because my fan is brushless or not but it does make a funny whirring noise. At full speed it won't throw the stir bar, probably because of the big magnets and how there is almost no gap between them and the glass.

This fan on amazon comes with a speed controller, used and old cell phone charger, and project box. http://www.amazon.com/gp/product/B00558OQ0W/?tag=skimlinks_replacement-20

Sorry to bump an old thread, but I can't get my LED dimmer to work for the life of me. I got this one

http://www.ebay.com/itm/DC12V-24V-8...s_and_Accessories&hash=item43c36500e6&afsrc=1

I simply wire + / - from Wall Wart to Input, and then Output to Fan, correct? Depending in Polarity it either doesn't spin at all, or spins at constant speed. Turning the knob does nothing. I'm using a 12V DC Wall Wart. Is it possible the unit is malfunctioning? This is a 4 PIN PWM fan, by the way, and I am just wiring 12V and GND out of the dimmer. Thanks!

jerkbag said:

........I simply wire + / - from Wall Wart to Input, and then Output to Fan, correct? Depending in Polarity it either doesn't spin at all, or spins at constant speed. Turning the knob does nothing. I'm using a 12V DC Wall Wart. Is it possible the unit is malfunctioning? This is a 4 PIN PWM fan, by the way, and I am just wiring 12V and GND out of the dimmer. Thanks!

Click to expand...

If you have a voltmeter, you might test the DC output voltage to determine if voltage is changing. The response of the multimeter should be slow enough that a variable DC voltage should be measurable.

raouliii said:

If you have a voltmeter, you might test the DC output voltage to determine if PWM is functioning.

Click to expand...

Yup I get ~12VDC steady throughout the range of the knob, which I believe is what a PWM should show (as I would guess the meter won't see the tiny pauses). Will take a closer look tonight. EDIT: Whoops didn't see the last part of your reply. Okay Dimmer must be faulty then voltage doesn't change.

I think I must have bought the wrong thing. With DC voltage input the dimmer stays steady at 12VDC, with AC voltage input it moves but only from 0 -> 2. With the former the fan spins full speed throughout out the dial range, the latter it buzzes but doesn't move throughout the whole range. I think I'm going to call it a loss and buy a 3 watt Pot.