Magnetic Stirrer w/ Hotplate for <$30

A magnetic stirrer with a hotplate allows you to mix and heat solutions with ease. These are commonly used in chemistry classrooms and cost upwards of $160! But I'll show you how to build one for less than $30.

Step 1 The Parts

These are the required parts:

• Thermoelectric Cooler ($14.75)
• Power Supply ($4.75)
• Motor ($1.25)
• Magnets x2 ($0.66 total)
• Potentiometer, 5K ($1.00)
• Switches x2 ($2.00 total)
• LED ($0.10)
• Enclosure ($1.95)

And that's all you need! Total cost: 26.46. Not bad for something worth more than $160!!!

Comments

[Jimmy Proton]

where did you buy your stuff, cause I only paid like $1 or $2 or the thermoelectric cooler and i already had most of the stuff.

[GreenD]

 What wattage was your thermoelectric cooler?

Why use a TEC instead of just a heating coil?

[knex gun enthusiast]

If you use a TEC in addition to converting all the electricity it gets into heat some of the energy is used to pull heat from the other side of the TEC to the hot side. IE if you have a TEC and put 100w of electricity in it might give you 110 w of heat (100w from the electricity 10w drawn from the cold side. It's just more efficient.

[articice]

I wonder why no one asked, why the R doesn't change the motor speed LOL

[GreenD]

So the hot glue will not melt because the otherside is kept cool correct?

[GreenD]

Last comment:
You have forgotten to mention that your power supply will need >10 amps, which isn't exactly inexpensive (more than 30$) and you also need to lable your amperage amounts on your potentiometers, etc...

[articice]

He also didn't predict that such current running through the LED or a potentiometer would quickly damage it. A thyristor-based (or other kind of power dimming device) regulation is needed.

[higgrobot]

Umm, why is your LED in series with the TEC??

[GreenD]

 yes, put it in parallel with an appropriate resistor.

[tinker000]

You can stack TECs to make a very large temperature difference IE h>c>h>c>h>c so one side cools (or heats) the next one in line.  But you need a lot of amperage and some decent cooling or a constant liquid filled container on it.  the bottom cool side would probably get down to freezing or thereabout

[kokonos]

what kind of magnets are they

[jimwig]

yed but use nut and bolts because hot melt glue melts......!!!!

[jesselfout]

Would it work safely at less than 100C (212F) ?

[stephenniall]

I made one of these but the 'thermoelectric cooler' i used a peltier unit which it gets cold on one side and hot on the other with a 12v wall supply and it got quite hot

[junits15]

that Termo electric cooler needs ALOT more power than a 9v wall wart try using a computer power pupply and if you do u can reach much higher temps

[I)AVI)]

The thermoelectric heater is likely too weak for reasonable heating. The author should put 500 ml or 250 ml of room temp water in a beaker and advise how many minutes it takes to get it boiling..

[Wired_24_7]

If I was running a basic chem lab, I'd definitely invest in a few of these! The hotplates in my lab have to be able to reach over 450C so this probably wouldn't work too well :(

[GorillazMiko]

at first i thought it said "magic stirrer" haha. cool instructable

[Hypocaust]

doesn't seem like ur eyes were workin

[gonzo_ja]

really good idea... i hadn't thought of the thermolelectric cooler. I wonder if a piece of ceramic would work as a good spreader to increase the surface.

[drectora]

Is there a way to gauge or control the heat as well?

[icinnamon]

A potentiometer will work well

[topdog849]

can i use this to cook ramen noodles?

[icinnamon]

Only if you add more power or a better heatsink...

[benstern]

I'm building a cooling magnetic stirrer.

[raidensdad]

Now could someone potentially put a potentiometer between the switch and the heat source to control the temperature? if so hello methlab lol j/k

[crapflinger]

i once "liberated" one of those fancy "real" magnet stirrers from my highschool lab...i used to use it to stir my chocolate milk

[icinnamon]

Nice! This one can create a huge vertex in a tub full of water, so I bet it could not only stir chocolate milk... but also froth it :D (and heat it to turn it into hot chocolate :D )