Intro: Tiny 80Watt Electric Heater
In this Instructable I'll show you how to make a small electric heater that works on 12volts and gives 80Watts of power.
It gives a nice little really warm breeze and will keep your hands warm.
I came up with the design myself.
Step 1: Parts and Tools
The parts you will need:
4x4x1cm 12volt computer fan
Some wire (at least 1mm thick)
About 1 meter of thin nichrome wire (you can get it from a hairdryer)
About 15 cm of copper or metal wire
A piece of sheet metal (at least 4x16cm)
4 screws that fit in the holes of the fan snugly
Some black electrical tape
The tools you will need:
A soldering iron with solder
A third hand
Step 2: The Parts of the Heating Element
To make the healing element you will first have to make some parts. Cut 5 pieces of nichrome wire that will draw about 1,4 Amps. You can just connect it to a 12 volt powersupply and measure the current and when that is 1,4 Amps you can measure the length of the wire and cut 5 pieces of the same length. Or you can measure the resistance of the wire with a multimeter and when it is 8,6 ohms you can cut it and measure the length of the wire. But be careful with the accuracy of your multimeter.
If you have 5 equal lengths of nichrome wire you can now take a little rod of 2mm wide and wrap the wires around it to make 5 springs.
Now we are going to make two holders for the springs by bending two pieces of copper or metal wire in the shape on the pictures. And make sure they fit on your fan with the screws.
Step 3: Making the Heating Element
First you will need to screw on the metal parts with the screws on the fan. Make sure they are above the fan so they can cool and don't heat up the screws and melt the fan. Now take a spring and twist it to the two metal wires, repeat this for the other ones aswell. You will need to solder them in place to prevent them from sliding around but you can't solder nichrome wire so you will have to make a little bridge of solder over the wire. I later used a smaller fan so that is why you see two different ones on the pictures.
Step 4: Connecting the Wires
Cut the wires of the fan shorter and take about 2cm of insulation of. Now unscrew the screws a bit, connect the wires of the fan and screw the screws back in place.
Now take your wire, drill a small hole in the fan and feed the wires through. Now take a bit of insulation of, unscrew the screws a bit, wrap the wires around the screws and screw them tight again. Make sure the polarity is the same as the fan. I used 0,5mm thick wire but after a while it gets pretty hot so make sure you will use at least 1mm thick wire becouse this heater will draw about 7 Amps. You maybe want to take the sticker of the fan aswell becouse it wants to peal of and you don't want it to touch the hot nichrome wires.
Now you can test it by connecting it to a 12 volt power supply that can deliver at least 7 Amps. I used a 17A lead acid battery.
When you connect it the fan should start blowing air and the nichrome wires should start getting hot. If you are not sure if every spring is heating up you can change the polarity. Now the fan won't blow and you can see if every nichrome wire get's orange. Don't do this to long or it will overheat! If not every spring get's hot you can check the solder connections.
Step 5: The Case
Every heater neads a case so you can't burn yourself. Take the sheet metal and cut it to 4x16cm and bend it into a square of 4x4cm. Make sure the heater and fan fit in it. Also make a square of 3x3 squares of the wire mesh and make sure it fits into the metal square. To solder it you will need your third hand and place the square in it like this. Now take your lighter, solder and third hand and go outside. Heat the square up and let the solder flow in the groof and wait a minute to let is slowly cool off. if it is right and your heater fits in it you can solder on the wire mesh with the lighter aswell. Be careful not to melt the seem of the metal square. Now clean it up a bit because it will get black.
To mount the heater in place you will need to put some electrical tape around the heater to prevent a short sircuit and make it fit snugly, it's just a friction fit. I cutted 2mm of my electrical tape to prevent it comming to close to the nichrome wires. Cut away the excess tape. Now just press it in the metal case. Check with your multimeter that there is no contact between each wire and the metal case.
Step 6: The Finished Product
Now your tiny 80Watt heater is done you can start using it. I know it is not totally safe so don't use it unattended and regularly check if it's not overheating. Don't blame me if something happens, make this at your own risk.
I hope you liked the project. If you have any questions leave them in the comments.