Stir Plate Speed Control

Hello there,

So I built my own stir plate following one of the many instructions from online. Last night I made my first starter with it. The only problem is that the potentiometer doesn't really control the fan speed. I turn it very slow and the second it starts getting power to the fan, the fan just goes full speed and I adjusting the potentiometer doesn't seem to do anything; so the stir magnet just gets kicked off. I have a 12V fan, 12V DC Adaptor (output?), and the potentiometer is a 10ka...or something like that. Any suggestions or tips?

Check your wiring again that it is correct sounds like a wiring issue that is the issue at hand. Almost sounds like the potentiometer is wired like a direct switch and its acting like a on/off without tempering the incoming current.

Here is how I have the wiring. Not the best job. Is this correct? I forgot the text for the far right arrow, but that is pointing to the wire going from the right potentiometer connector to the fan.

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Try an LM317. It provides much better control than just a potentiometer. You can get them relatively cheap off ebay and you should be able to dig up some info on how to incorporate it.

BBL_Brewer said:

Try an LM317. It provides much better control than just a potentiometer. You can get them relatively cheap off ebay and you should be able to dig up some info on how to incorporate it.

Click to expand...

Is this something that Radio Shack may sell? I am hoping to get this resolved today, so I can step up my starter tonight. I also don't know how to solder.

I just built one last night, I'm using a 25ohm pot I got from radio shack. Its 3 prong when looking down on it left prong is + middle is the feed (positive wire on fan) right prong is ground for both fan and power. Works well for me with a good range of speed