SRC Member Thexder Posted July 10, 2009 SRC Member Share Posted July 10, 2009 If you are like me who needs to mix additives to maintain Ca, Mg, Ph, Kh in your tank. You will know how difficult it is for some of the additives to dissolve in DI water. Of course you can just dump the additives in your sump but it can do more harm when the additives don't dissolve fast enough and lands on your corals. I'm lazy to stand or sit around to stir the solution until it mixes completely, so I've decided to DIY a magnetic stirrer. This is used in labs to mix chemicals. Basically it has a magnet on a motor. There is a stirring bar in the container which is magnetised also. When the motor turns, the bar also turns by magnetic force thus mixing the solution in the container. Some of them also have a hot plate to heat the solution, but we don't need that for our purpose. Such units cost around $200 or more. After checking other DIYs on magnetic stirrers, here are the basic parts you need: 1) Motor - Most people use the fan from a PC 2) Strong magnets - Most people strip the magnets from a dead hard disk 3) Stirring bar - Can buy or make your own from iron/magnet 4) 12VDC supply Quote Link to comment Share on other sites More sharing options...
SRC Member Thexder Posted July 10, 2009 Author SRC Member Share Posted July 10, 2009 A trip down to Sim Lim Tower and I got the following: Project box: To contain the fan, electronics, and also to support the container for mixing. This cost me $4.50 but you could get an unused Tupperware box from your home and its FOC. The box must be plastic (or non-metallic). If you use a metal box, the metal will interfere with the magnetic field and you won't get good results. Quote Link to comment Share on other sites More sharing options...
SRC Member Thexder Posted July 10, 2009 Author SRC Member Share Posted July 10, 2009 12VDC fan for PC. I got this design because it has a good flat and unobstructed surface to attach the magnets. Otherwise the standard PC 3" fan will do. The cost was $8.80 but its FOC if you can get from a spare or dead PC. Quote Link to comment Share on other sites More sharing options...
SRC Member Thexder Posted July 10, 2009 Author SRC Member Share Posted July 10, 2009 PWM speed control. The fan speed has to be controlled. If it spins too fast, the magnetic force is not strong enough to couple the stir bar to the fan. I opted for the PWM because its a more efficient way to control a DC motor but the cost is higher. This kit cost me $9.60. You can use a cheaper option by using a potentiometer to change the voltage to the fan directly (probably $2-$3). Quote Link to comment Share on other sites More sharing options...
SRC Member Thexder Posted July 10, 2009 Author SRC Member Share Posted July 10, 2009 Magnets. You need quite a strong magnet to spin the stir bar, and HDD magnets are the easiest to get for the rare earth magnets. I got this pair from the junk shop on the top floor of SLT for $4. Its FOC if you have a dead HDD lying around... Quote Link to comment Share on other sites More sharing options...
SRC Member Thexder Posted July 10, 2009 Author SRC Member Share Posted July 10, 2009 Some other miscellaneous parts like control knob, power switch, adaptor pug. Other parts not shown here which I have in my spare parts box - LED, wires, resistors, screws, etc. Quote Link to comment Share on other sites More sharing options...
SRC Member Thexder Posted July 10, 2009 Author SRC Member Share Posted July 10, 2009 Last but not least, 12VDC power supply. Cost is around $12-$15. Again its FOC if you have a spare one lying around as a charger for handphone, phones, etc. Otherwise, your PC power supply is also possible Quote Link to comment Share on other sites More sharing options...
SRC Member Thexder Posted July 10, 2009 Author SRC Member Share Posted July 10, 2009 First we got to remove the magnet from the steel plate. They are normally glued on. I used a hammer and flat head screwdriver to remove them. If you whack too hard, the magnets might break. Just a few firm taps will do. Quote Link to comment Share on other sites More sharing options...
SRC Member Thexder Posted July 10, 2009 Author SRC Member Share Posted July 10, 2009 Attach the magnets to the fan. You need to glue or stick them (I used 3M double sided tape) or they will fly off when the fan spins too fast. Also note that you need to find the right position to place them otherwise the rotation is not balanced and the fan will probably wear out very fast. 1 magnet is actually good enough. Quote Link to comment Share on other sites More sharing options...
SRC Member Thexder Posted July 10, 2009 Author SRC Member Share Posted July 10, 2009 Ok, now to assemble the PWM speed control. Opened the package and damn... the instructions are in Thai But just follow the circuit diagram which is self explanatory. Again if you are not confident in soldering or electronics, then better to use a simple solution with the potentiometer as the chances for making mistakes are lower. My circuit didn't work the first time because I soldered a diode in the wrong direction Quote Link to comment Share on other sites More sharing options...
SRC Member Thexder Posted July 10, 2009 Author SRC Member Share Posted July 10, 2009 Mechanical assembly of the enclosure. Some drilling and cutting required to insert my power switch, control knob. Quote Link to comment Share on other sites More sharing options...
SRC Member Thexder Posted July 10, 2009 Author SRC Member Share Posted July 10, 2009 Fully assembled with the fan above the speed control PCB. I used wall plugs and PC spacers to raise the fan height. You need the magnet to be near the top surface. I added the LED to indicate power on. The switch is supposed to have a light when power on, but didn't seem to work or I don't know how to connect it As can be seen, I used 1 magnet which is sufficient. Quote Link to comment Share on other sites More sharing options...
SRC Member Thexder Posted July 10, 2009 Author SRC Member Share Posted July 10, 2009 Side view to show the clearance below. Quote Link to comment Share on other sites More sharing options...
SRC Member Thexder Posted July 10, 2009 Author SRC Member Share Posted July 10, 2009 The completed DIY magnetic stirrer Quote Link to comment Share on other sites More sharing options...
SRC Member Thexder Posted July 10, 2009 Author SRC Member Share Posted July 10, 2009 Testing with a small bar magnet as the stirring bar in a 100ml jar... I'm now trying to DIY a stir bar. You can buy the commercial lab stir bars but I enquired and it costs like $10~$30 for 1 Supposedly, a nail, metal wire or paper clip should work, but doesn't seem so in my case. Will add more updates once I have a proper DIY stirring bar. Quote Link to comment Share on other sites More sharing options...
SRC Member albinosage Posted July 10, 2009 SRC Member Share Posted July 10, 2009 Phweeeeet~ Nice DIY project, thanks for sharing! Quote My 1.5ft nano cube My 24G nano tank (Decommed) I can picture in my mind a world without war, a world without hate. And I can picture us attacking that world, because they'd never expect it. -- Jack Handey Link to comment Share on other sites More sharing options...
Gouldian Posted July 10, 2009 Share Posted July 10, 2009 Nice... Thanks for sharing! Quote "Reefs, like forests, will only be protected in long term if they are appreciated" Dr. J.E.N. Veron Australian Institute of Marine Science -----------------------------------------------------------------------Member of:UEN: T08SS0098FPlease visit us here: http://www.facebook....uaristSocietySG Facebook Group: http://www.facebook....gid=34281892381 Link to comment Share on other sites More sharing options...
maxteo98 Posted July 10, 2009 Share Posted July 10, 2009 nice idea! seems like it can be further refined to work like a vortech wave maker. Quote http://www.maxette.com Link to comment Share on other sites More sharing options...
SRC Member Thexder Posted July 10, 2009 Author SRC Member Share Posted July 10, 2009 nice idea! seems like it can be further refined to work like a vortech wave maker. The same concept is used in kalk stirrers. Quote Link to comment Share on other sites More sharing options...
SRC Member jyoon Posted July 10, 2009 SRC Member Share Posted July 10, 2009 Hi Bro Thanks for sharing. Will try out. Quote Link to comment Share on other sites More sharing options...
SRC Member peacemaker Posted July 10, 2009 SRC Member Share Posted July 10, 2009 Sweet DIY! 　 Quote Link to comment Share on other sites More sharing options...
SRC Member Thexder Posted July 11, 2009 Author SRC Member Share Posted July 11, 2009 I found this shop called Practical Instruments located at Balestier Hills Shopping Centre which sells the magnetic stirring bars. $5 for a 1.5" stir bar. They have other sizes too. They sell laboratory instruments and consumbles so you can get other lab supplies also. Anyway, I'm still trying to DIY a custom stir bar or plate for my other container which has an uneven bottom. Quote Link to comment Share on other sites More sharing options...
reef999 Posted July 14, 2009 Share Posted July 14, 2009 Thanks for your great idea!! Today i hv done a simple one without the speed controller and box. I am using the 12VDC adjustable voltage adapter for the 12V fan. Also DIY a stirring bar. 6V setting result. And video showing adjusted from 0V-->4.5V-->6V-->7.5V-->12V-->0V. Quote Link to comment Share on other sites More sharing options...
SRC Member Thexder Posted July 14, 2009 Author SRC Member Share Posted July 14, 2009 Great! Can show how you DIY the stirring bar? Quote Link to comment Share on other sites More sharing options...
reef999 Posted July 14, 2009 Share Posted July 14, 2009 I am using the some small broken magnet from hard disk and insert into a teflon block. Here's the cross section view Quote Link to comment Share on other sites More sharing options...
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