DIY Stir Plate Questions...

[theck]

I have been looking at doing a stir plate for a bit now and remembered I had an old firewire (yes firewire) external HD. The nice thing is that it has a rocker switch and led light on the front... so I ripped it apart and pulled the magnets out and had a few questions before I build. I should be able to just snip (or connect) the wires going to the old HD and connect the fan into that right? The yellow is 12v vs. the red 5v, I assuming I want to use the yellow? Can I attach a potentiometer between the fan and yellow to control the speed? I have yet to get a fan but they aren't much bigger than an HD right, should fit fine? Thanks!

 

[Indian_villager]

I'm not sure how many amps the 5v side of that circuit would put out. I'd play it safe and use an old phone charger.

 

[theck]

I'm not sure how many amps the 5v side of that circuit would put out. I'd play it safe and use an old phone charger.

The power supply says 5v = 2a, and 12v = 1.2a... is that too much still?

 

[motleybrew]

A pot in series would work. Typically, a fan can draw between 500 to 800 ma (correct me if I'm wrong). The 5v will give you a much lower rpm, maybe too low. I have mine running on 9v I believe.

 

[slatts]

I bought a fan on amazon that was usb powered. That means all I had to do was plug'er into an old iphone plug. Can't control the speed but it works really well running full out.

 

[theck]

A pot in series would work. Typically, a fan can draw between 500 to 800 ma (correct me if I'm wrong). The 5v will give you a much lower rpm, maybe too low. I have mine running on 9v I believe.

Use the 12v? Won't be any issues?

 

[motleybrew]

A DC computer fan is designed to run from the 12V rail. You just need to use a properly sized pot for the job (around 2 watt, probably).

 

[theck]

A DC computer fan is designed to run from the 12V rail. You just need to use a properly sized pot for the job (around 2 watt, probably).

Thanks. I'll bring it all into radio shack and hopefully one if them might know what is the best sizing. Start at 2 if it's some teen ha...

Sent from my SGH-T769 using Home Brew mobile app

 

[theck]

Only pot they had was 3 watt. Of course it was a teen that had no idea I'll pick up a fan and try it tomorrow.

Sent from my SGH-T769 using Home Brew mobile app

 

[blkhrt]

Depending on the amps needed by the fan is what you need to build for. I built some ECG projects using computer fans for school but had to add a transducer for amp multiplier. The 2 amps may be to much for the fan find out what it's max is and try to stay around 70% of it.

 

[theck]

Picked up a used fan from a local computer store... $3 and got the pot $4.85, total $7.85. Connected to the yellow and runs nice and fast. Control works great too. Can't wait to get it all back together and give it a try.