Stirplate DIY - no juice to fan

[isukendall]

I'm working on a DIY stirplate to install in a cigar box, much like the epic thread that I found somewhere on here. I have a very simple problem: I cannot get any juice to the fan.

I'm not a total wiring noob, I have some electronics background as an engineer, but I can't figure it out. Seems to test the fan, I should be able to wire the two leads from the fan directly to the outlet plug. Fan specs are 12V DC, 0.32A.

So far I've tried three plugs, one from a PC charger (12V 3.0A), one from a cell phone charger (5.5V, 500mA), and another from who knows what (13V, 0.8A). I assumed that the 13V may not work having too much voltage, but none of the others work as well.

Should this work to wire up directly? I want to start out testing that the fan itself works. I did get it to spin once with the PC charger, but after stripping the wires shorter and retrying, it no longer works. Could the fan be burnt out, or am I doing something completely wrong here? Thanks for the help.

 

[Alucard1983]

A lot I fans the energy goes one way try switching wires. The fan will run at 0.2 amps. I tryed a few power packs they were to weak or spun too past. I said screw it and bought a multi adaptor from Walmart for 20 dollars it runs at 1.3 amps and has mutiple voltages. From 12 volt down to 3 volt. I did not build my with speed control so I use te switch on the adaptor to voltage it down to slow it. I usually run mine at either 9v or 7.5 v for a 1 L flask

 

[isukendall]

I forgot to mention but I did try switching wires. I have so many plugs that I'd like to do it without buying something new. Mine isn't even weak or too fast, I just can't get it to go at all.

 

[isukendall]

I got a new fan, and got it to run off a 9V battery. Guessing the other fan is dead. Sorry to start such a bonehead post.

 

[TheDudeLebowski]

You might have blown the original fan. If there's no typo in your original post you may have been trying to put 12V/3.0A power into a 12V/.32A fan. I don't know how many engineering teachers told us that voltage won't kill you but current will ;-)

 

[ETCS]

I had the same problem my first go around in making a stir plate. Turns out, the problem was the magnet that I had attached to the fan was too strong and would not let the fan turn.

 

[Toymaker]

Do your chargers still work? You may have blown them. They are not designed for inductive/motor type loads. Try a car battery to test the fan. if it works you may need to find a better 12 VDC source. something like this would work well http://www.trcelectronics.com/Meanwell/mdr-40-12.shtml
We use Meanwell power supplies at work They are easy to hookup and hold up well.

 

[Clementine]

You might have blown the original fan. If there's no typo in your original post you may have been trying to put 12V/3.0A power into a 12V/.32A fan. I don't know how many engineering teachers told us that voltage won't kill you but current will ;-)

No it won't

Not wanting to make this elec eng lesson but the circuit will determine the current based on the load and voltage. So a 12volt 3 amp power pack will not blow a 12 volt fan as the fan will only draw what current it needs. The question is was the 12 volt power pack a regulated power supply or unregulated if you put a volt meter on most power packs they range from 13 volts to 17 volts. PC fans run from the 12volt rail of the ATX power supply and hence they are only designed to operate with 12 volts or just a little more applied to it.

For the op
You will want to make a variable speed stir plate driving the stir bar too hard cause it to fly off and sit against the side of the flask. Check out the Lm317 to make a variable voltage power supply.

Clem

 

[Stick]

My attempt to salvage an old CPU fan resulted in a similar failure. New, cheap one works great!