Magnetic Stirrers here in Brazil often have a very high price.Based on various projects available on the internet, why not make your own?We use this case:1 Wooden box1 80mm Fan @ 12Vdc1 Circuit Speed Controller1 HD magnet 1 power source 12Vdc/500mA - Saved from a older router.1 on / off switch4 screws8 nutsSome wires, tools, Gorilla Glue.For the speed controller, there are several options, from a simple potentiometer until to a PWM circuit using an 555 IC.I chose the PWM method for speed control, because the accuracy of rotation required as the substances used.Usually, the potentiometer is used for adjusting the speed of rotation and the value of this depends on the potentiometer control circuit chosen.Example of "simple" circuithttp://www.instructables.com/id/Make-your-own-Magnetic-Stirrer-2S/?lang=ptExample of PWM circuithttp://www.instructables.com/id/Very-simple-PWM-with-555Modulate-every-thing/http://www.instructables.com/id/Yet-Another-Simple-Pot-controlled-555-PWM-generato/First step, perform the necessary drilling in the box, taking care to keep the drilling of the fan, centralized.Install the chosen circuit, as well as potentiometer and key in the holes made.Glue magnets on the fan, as centered as possible, avoiding the propeller unbalance.Connect the fan to the previously installed circuit. To position the fan to the desired height, adjust the screw nuts support.The maximum speed achieved depends primarily used the magnet, and the viscosity of the substance.We can test this circuit, using a magnetic stir bar and Erlenmeyer.First Test: Who has aquarium knows the importance of lighting for plant growth and for the beauty of the environment.There are several options from many different prices. For a basic aquarium lighting, LED technology can help.The idea is to be as simple as possible, at lower cost and provide adequate lighting to the aquatic environment.It is used as a basic rule the proportion of 1W per liter of water for proper lighting.My aquarium has 120 liters, 100 liters useful.Using the rule, it is expected 100W light for the correct illumination.When searching the Internet, I found led strips, single color (pure white) or RGB, allowing customize the color best suited for your environment.Are sold in rolls of 5m with 300 leds of the model 5050, and with power of 72W.Although 72W is less than 100W, I decided to assemble the solution and the result was excellent for my purposesThe solution:5 meters of Led strip RGB 50505A 12V power supply1 RGB ControllerThey are sold in kits:http://www.ebay.com/itm/300-LED-5M-5050-RGB-SMD-Light-Strip-Lamp-44Key-IR-Remote-12V-5A-Power-Supply-/201381358965?var=&hash=item2ee343ad75:m:mhYJU59NgsqW56qid0HBB2g1.5 mts Aluminum profile like this.1 Double-sided tape50cm - 4 way ribbon wireTools such as soldering iron, pliers, wire ...I used 1.5m of aluminum profile like a picture above, cut in half and stuck, forming a profile of 75cm with twice the width.I cut the LED strip into several pieces of 75cm to the same extent of aluminum, and pasted inside.Thereafter the weld has been made between the multiple pieces of tapes using the ribbon wire.At the end we can see all the LED tape, several pieces fixed inside the aluminum profile.Once you make the connection, use a black sticker on the other side of the aluminum profile for a better finish. After that, turn on the tape with the 12V supply and select the desired color.Ready light for aquarium simply and inexpensively. Bem, preciso ler a temperatura do oleo