stir plate question

[fantomlord]

trying to put together a PC fan stir plate, and wondering which rheostat I need...how many ohms? how many watts?

I see 25 ohm, 3 watts and 5 Mohm, 2 watt...which one, and why?

thanks

 

[pshankstar]

Not really sure, but I just bought these Potentiometers to adjust the fan speed. I'm sure that's what you are looking to do with a rheostat. I'm using a 12V 0.5A power adapter from an old wireless router. I hope this helps!

 

[Konadog]

I used something like this for mine. Super easy, just wire in the fan and add your power supply.

 

[Murphys_Law]

I got something like this and it works fine. Just change the setting and the fan speeds or slows. This isn't what I got exactly but same concept.

http://www.amazon.com/dp/B001DT7BHM/?tag=skimlinks_replacement-20

 

[KPBrews]

Not really sure, but I just bought these Potentiometers to adjust the fan speed. I'm sure that's what you are looking to do with a rheostat. I'm using a 12V 0.5A power adapter from an old wireless router. I hope this helps!

Based on this DIY article:

http://www.stirstarters.com/instructions.html

... I'd be careful using simple pots to adjust the speed.

I have seen some designs that use just a pot for speed control. I don't recommend this. At low speeds, you are using the potentiometer to drop the full voltage from the power supply which could be several watts. Most pots are designed to dissipate ¼ to ½ watt. They won't last long operating like this.

The PWM controller like the one Konadog linked above is probably the most ideal method. And considering how cheap they are (assuming you can wait for them to arrive from China), I see little reason to go with a part that could burn out instead of the right tool for the job.

 

[pshankstar]

Based on this DIY article:

http://www.stirstarters.com/instructions.html

... I'd be careful using simple pots to adjust the speed.



The PWM controller like the one Konadog linked above is probably the most ideal method. And considering how cheap they are (assuming you can wait for them to arrive from China), I see little reason to go with a part that could burn out instead of the right tool for the job.

Thanks for the info, I had not come across that article during my research. The articles I have read that used POTS for RPM control never mentioned this.

If it seems like it doesn't do the job for very long, I'll look into other alternatives but for now I have four backups in the mean time while I find another solution. This thread is nice to see what others are using.

 

[KPBrews]

Thanks for the info, I had not come across that article during my research. The articles I have read that used POTS for RPM control never mentioned this.

If it seems like it doesn't do the job for very long, I'll look into other alternatives but for now I have four backups in the mean time while I find another solution. This thread is nice to see what others are using.

Stir plates are pretty simple devices. Nearly an infinite number of ways to make them, all of which probably work just fine, short term (or even long term, you never know).

I think some will last longer than others, however, based on the components selected. Considering how cheap and easy they are to make, that may not be a big deal. But since the price difference is small ($2) for the "right" tool compared to a less-ideal tool, I would want to use the one specifically designed for the application. (at ~$5 for 5 pots, you'll have 4 spares laying around useless unless you have another need, but at ~$7 for the PWM controller, you only paid ~$2 more but shouldn't have to worry about them burning out for a good long time)

Back when I built a lot of custom computer enclosures, I wouldn't have dreamt of using a pot for fan speed control... PWM is the normal method for reliable continuous fan operation.

 

[Mike_c]

I used this:
Yeeco

3.8 out of 5 stars**7Reviews

Yeeco TY100 LM317 Linear Full-stage Voltage Regulator Volt Regulated Board Fan Speed Controller Control Switch Governor Governing

It even has the pig tailed pin connections. Will need a knob.
Built totally of cast off parts from old desktop PC. Grand total for my stir plate - $11