Will this work for a fan/stir plate controller?

[ThreeDogsNE]

i stumbled upon these on the web. http://www.ebay.com/itm/LED-Light-L...A%2BFICS%2BUFI&otn=21&pmod=260953797439&ps=54

My knowledge of electrical stuff is pretty much limited to black and white wires on diagrams and switches. I am getting stuff together to build a few stir plates, collecting computer fans, and getting rare earth magnets. (I plan to give some to family members who brew, as well as use some myself). I was going to order the 25 ohm 3W rheostats from Radio Shack, but they are currently out online. Would these work in their place? Thanks in advance.

 

[ThreeDogsNE]

Bump. Anyone? Any thoughts on these?

 

[Apoxbrew]

are you not near a B&M radio shack?

 

[william_shakes_beer]

I bought a PWB controller, but when I went to the electronics store I was forced to buy a variable voltage wall wart. It goes from 1.5V to 12V. Works just fine at 3 volts, makes a nice little dimple. Now I have a PWB controller collecting dust in my basement.

 

[aggiejason]

Was there ever a conclusion on this? It seems like the popular choice is the 25ohm pot inline with the power supply but I would assume that a PWM style controller will give you better speed control particularly at low speeds.

The unit above is available all over ebay and even Amazon.
http://www.amazon.com/dp/B003L4KKF2/?tag=skimlinks_replacement-20

I've seen it as cheap as $2...cheaper than a trip to Radio Shack.

The only other post I've found related to this, however, seems to indicate that the PWM controlled stir plate was noisy but that could just have easily have been from the fan/mounting itself.

Curious to hear if anyone has tried one of these cheap LED dimmers as PWM controller for their stir plate.

 

[aggiejason]

So..... I ordered one to give it a try so that I could set my curiosity to bed. The dimmer works great in terms of having high adjustability of fan speed. The frequency of the PWM for that LED dimmer does, however, cause the fan motor to whine at pretty much all speeds. It's at a pitch that is pretty irritating. I would not consider this to be a usable solution.

I took it apart to see what was inside. The PWM signals are being generated by a dual 555 timer circuit (one to set the clock frequency and the other one to handle the adjustable PWM. A reasonable solution would presumably be to swap out some of the resistors to adjust the clock frequency such that it's more fan friendly.

For now I'm going back to the rheostat and saving that project for another day. I've got yeast that needs stirring!