Introduction: Desk Fan/heater

Picture of Desk Fan/heater

The fan gives you coolness on a hot summer day.  The heater inside provides you with a warm breeze in those cold winter months. This fan/heater comes with a ambient led indicator:  cold=blue, warm=purple. The fan speed and the amount of warmth can be fine-tuned.
As an extra it is suitable for extracting harmful solder fumes. Replace those bulky desk fans with this smaller more convenient fan.

The total cost of the desk fan/heater =  7 dollar. The only part I bought was the PWM dimmer, all the other parts were laying around in my garage.

Step 1: Materials and Tools

Picture of Materials and Tools


  • Power Jack
  • Spring
  • Turning knob
  • Wooden board 9mm thick
  • Wooden stick 12mm in diameter
  • Switch
  • Computer fan 12v
  • PWM dimmer
  • RGB led strip
  • Power supply 12v 3amps minimum
  • Electric wires
  • Copper rods 10cm long 1,5mm thick


  • Super glue
  • Wood glue
  • Wood wax
  • Jig saw
  • Sand paper
  • Wood clamps
  • Drill
  • Drill bit  5mm, 6mm, 7mm, 12mm
  • Hole saw 90mm
  • Solder
  • Solder iron

Step 2: Sawing

Picture of Sawing

The final product will be a cube. The wood I used is 9mm thick so every measurement is made keeping the thickness of the wood in mind.

Saw 2 squares of 12x12cm, 3 squares of 10,2x10,2cm and 2 rectangles of 10,2x12cm, 4 little rectangles of 1x1,5 cm.

Saw 2 pieces of 3cm from a wooden stick (12mm in diameter).

Step 3: Drilling

Picture of Drilling

I made a drawing of the ventilation holes in Sketch Up, which you can download below. Glue these drawings on the two 12x12cm pieces and drill the circles out using a 12mm drill bit.

Drill a  hole (7mm in diameter) 2,5 cm from the side of one 10,2x10,2cm piece

Drill two 7mm holes 2,5cm from the side of another 10,2x10,2cm piece, leaving at least 2,5 cm of space between these two holes.

Drill a 9cm hole in the middle of the last 10,2x10,2cm piece and drill a 5mm hole on the side (for putting through a cable).

Drill a 5mm hole in the middle of each 1x1,5 cm piece.

Drill two 12mm holes on the  long side of a 10,2x12cm piece 1,2 cm from the side and 7cm from each other.

Step 4: Gluing

Picture of Gluing

Glue two 10,2x10,2cm pieces (square angled) to one 10,2x12cm piece.

Glue the 10,2x10,2cm piece with the 9cm hole in the middle between the two other 10,2x10,2cm pieces approximately 3cm from one side.

Glue the last 10,2x12cm piece on top of the 10,2x10,2cm pieces.

Glue the two 3cm pieces into the 12cm holes of the 10,2x12cm piece.

Step 5: Heating

Picture of Heating

The heating is done by a spring stretched between two copper rods.

Don’t just use any spring but measure the amperage first by applying a heavy 12v source and a multimeter.  My spring drew about 2,5 amps so it will produce about 30watt of heat at 12v . Well 30watt is not a lot, it will not heat up a room. But it will give me a warm stream of air on me while working on my desk.

Solder the spring between  two 10cm copper rods.

Put the four 1x1,5cm wooden pieces on each end of the rods. Glue these pieces in the corners of the so far wooden box in front of 10,2x10,2cm piece with the 9cm hole.

Solder a cable on each copper rod.

Glue one 12x12cm piece in front of the box for the spring.

Step 6: Electronics

Picture of Electronics

Solder cables on the positive, blue and red of the RGB led strip and glue it in front of the 1x1,5 pieces. Put the wires through the 5mm hole.

Glue the fan in to the box. Watch the direction of flow indicated on the fan.

Glue the power jack, the switch and the PWM dimmer in place.

Follow the schematics in the picture to connect everything together

If you do this correct the blue led and the fan will start to work while you turn the potentiometer of the dimmer. When you push the switch the red led turns on (together with blue it will be purple), and the spring will become warm. Caution: the spring should never be under tension without the fan turning, otherwise the spring becomes too hot and will burn down.

Glue the last 12x12cm piece on the remaining side.

Step 7: Finishing Touch

Picture of Finishing Touch

Gently sand the whole cube.

As finishing you can apply wood wax.   

Step 8: Enjoy

Picture of Enjoy

Well, that’s it. After the hard work making this you can relax and enjoy the gentle breeze of your just made desk fan.


gregdavid1 (author)2015-02-01

Have you considered using large rectangular ceramic resistors (like those used in a power soak) as your heating elements? Being basically springs enclosed in ceramic (like Calrod stove elements) I think they would be a much safer alternative to a bare spring, esp. in a wooden box with limited airflow and no other safety features (fuses, tip-over switch, thermal liner, etc.). Of course, I also think you should add a few safety features, esp. two fuses, one current, the other thermal eve with the safer resistor.

SomtoA1 (author)gregdavid12017-05-27

Good idea. I am a trying to build a heater. I have a 20 watts ceramic resistor but I do not know it's max temp, max volt, max current and resistance. (

Why didn't I think of that?

MonilS (author)2016-11-02

Wow, Its amazing...

but if this work on 5V then everybody can use with mobile charger or mobile power bank...

Actually i also required.

if any have circuit with 5v please mail me.. (

Rambo32 (author)2016-10-19

what about using nichrome wire instead of the spring?

deluges (author)2016-09-08

This is a really cool project, it's going straight to the "to do" list

jdmumper (author)2012-07-19

I like the look of the wood box. It might be fun to hack in a Peltier heating/cooling element. I have no design to offer, but... Here's an example device that will raise the required current to 6+amps, but might be useable with the proper aluminum fins...

ykgarg007 (author)jdmumper2014-12-08

man is there any way to increase current in TEC1- 12706 .. I used pc 300w power supply 12v which capable to give20amp but peltier takes only 3amp.
and the other thing to control the temprature on off switch ... i have some thing idea about this but main problen is to draw more current..

bmiller91 (author)ykgarg0072016-08-22

A peltier is just a heat pump so you might be able to get a cool stream of air but you'd be dumping heat back in to room + heat from power supply = net loss.

daniel_bingamon (author)2015-12-03

A small switch on the underside would be good to shut it off in case it gets knocked over.

Just use a tilt switch, when it falls over, it breaks the circuit automatically, and also resets itself when placed upright.

easymods45 (author)2015-12-23

I am trying to make it, I have a fan that is 12v at 0.15 amps and a spring that when I put power through gets hot but I can't measure the power it draws and if it will work with my 9v at 2amps and 18watts power supply

HugoAlex (author)2015-12-08

Good job!

PankajK42 (author)2015-12-07

Please tell how you calculate heat for spring

Check it's amp draw, and the voltage it's running at, and calculate the wattage. The internet has plenty of info to calculating wattage.

diy_bloke (author)2015-12-05

Let me just emphasize again that I love the idea and it also looks really good and I am all for building stuff yourself, but out of safety concerns I would opt for this one for 13 USD:

ArthurOwen (author)2015-01-29

This device is totally illegal in the United States. I can not speak about other countries. It is a fire hazard of the first order. Even if it were not illegal, a wood box for an electric heater is absurd.

diy_bloke (author)ArthurOwen2015-12-05

Nothing illegal about it, but you probably would not get it certified to sell

jgraham26 (author)ArthurOwen2015-12-03

How is it "illegal"? What U.S. code does it break?

In any case, so what? We DIY'ers aren't bound by feel-good legislation that forces us to rely on experts to do our projects for us. Hopefully, we use a bit of common-sense and make things as safe as we can and include safety warnings in our articles, legality be damned....

I'm just sayin'....

ac-dc (author)jgraham262015-12-03

It's not illegal but it could be a potential fire hazzard. Besides that being a risk to inhabitants, it could also void your insurance so a possible risk of many thousands of dollars.

However, the risk is mitigated quite a bit by certain design elements such as having only 12V input, and the relatively low thermal density of a spring which if it were to fail, which it very well might, then be very hot falling onto the wood, it isn't likely to catch the wood on fire.

Regardless the whole project is sort of silly when you can buy a ready made, UL listed heater for under $30 with desirable safety features such as overheat and tip-over shut off protection, not even considering the value of one's time or the wood or 12V PSU and other parts.

Even so I suppose people need hobbies to keep themselves busy, but personally I would have just used a 150W light bulb with a fan behind it, with a diode in series to reduce wattage but give it a very long life at the lower power, then you don't need the sketchy spring heating element contraption or 12V power supply, and when a bulb fails it just burns the filament inside, assuming you very securely attach the outlet base to the box so it can't fall off.

MorzenM (author)2015-12-03

Great idea! For safety, I would use a 30-50 watt light bulb instead of the spring for safety.

What would be cool would be a matching speaker for your desk.

diy_bloke (author)MorzenM2015-12-05

agree. I was thinking 'lightbulb' too

diy_bloke (author)2015-12-05

it is a nice idea. look sgreat, but yes the wood is a bit worrying but maybe I am too careful. I have a 15 watt soldering iron though that can burn wood

shags1 (author)2015-12-04

It looks neat, but a heater with a wooden body and grill is not a smart idea.

CamdenS (author)shags12015-12-04

That is what I was thinking

Yonatan24 (author)CamdenS2015-12-05

Same, 30W can be pretty hot

brass90 (author)2015-12-03

What do the colors in the electrical schematic represent? Please redo ur instructable with a legend defining th colors. and please include a photo of where th copper rods ar mounted in th box, a comment or two about th safety of having heated copper rods mounted into wood panels would be reassuring. As it is now, this seems to be describing a how to burn down ur living area or domicile . Is there any heat absorbing brackets that hold n dissapate th copper rod's heat, so as to reduce th heat transfer to an ancient fire-fuel known as wood.

mrjdos007 (author)2015-12-03

great idea,perfect for ur desk, very simple,

safe,,, long as it is not next to ur gas can on the floor with puppies running loose in your room with shag carpet,

I think its cool,and it works for u,and u posted it,its instructables,there is always other ways to modify any project

Mark 42 (author)2015-12-03

This gives me an idea... I have a heating element from a coffee cup warmer that had a meltdown. The rest is straightforward enough.

Raphango (author)2015-12-03

Very interesting!! =D

snotty (author)2015-10-16

This is really pretty. Pretty dangerous too, as everyone already said. A bit more safety built in and this could be top notch :)

Salman Naveed (author)2015-05-25

Incredibly innovative!

As an addition, I would like to suggest the formula POWER= VOLTAGE x CURRENT (P=VI). This will be helpful in calculating the amount of heat in Watts produced by the heater.

crashzoom (author)2015-03-23

Very cool.. I have ordered a fan from eBay but it is too weak to fit this project

phillipcd (author)2015-03-04

that's a great idea......

MichaelS38 (author)2015-02-09

Great idea - I would like to suggest my twist to the project. Instead of springs, use 12V halogen bulbs. That would be safer, easy to get and easy to wire bulb connectors. Whats more it could also be used as a light source. You could beef the heating ability up as much as you want (by adding more bulbs). Also paint a thick coating of plaster on the inside of the wooden box, for a flame retardant.

Last but not least plugin a washing machine thermostat to control everything. That way you can sleep with worries of the heater becoming a fireplace.

mpikas (author)2015-01-29

Don't get me wrong, I like the idea, a neat little box that can give you a little extra heat. Great.

A random spring (even with a reasonable power draw) stretched across 2 terminals in a wooden box with no thermal or overload protection (besides what is in the power supply, which was not designed for this use), you're just asking for a fire. When that spring gets warm it will sag, it could contact something eventually, it will eventually break, you could end up with a very hot piece sitting in the bottom of the box (wood can combust at a little over 4-500*, that piece doesn't even have to be glowing hot >1200*). Even if all that is OK, those fans tend to eventually fail/seize, sometimes from just sucking up a little bit of dust. Kill the airflow and that spring will get _a lot_ hotter, fast (though I would imagine that a little bit of airflow will fan the flames and make the situation worse if you can keep things hot enough to combust).

I generally refrain from being a safety natzi, mainly because I feel that we are way over regulated, no one assumes any personal responsibility, and heck, I don't always do things in the safest way. But this thing... If you're sitting right there and pull the power as soon as it starts smelling funny... well then it's fine, but you can get up for a minute, or heck, half the people that would look at this instructable and think it's a great idea would leave something like this plugged in overnight or over a weekend...

If you want to put a heating element in something like this look at how similar devices are made- typically a thermal shutoff, a position shutoff (turns off if it gets knocked over), overload protection and EVERYTHING near plus everything downstream of the heating element is made of non-flammable materials (and typically outside surfaces are insulated from the inside to prevent burns from direct contact to heated surfaces).

gregdavid1 (author)mpikas2015-02-01

Even just one 12V inline 3A-4A fuse for the heating element, plus a thermal fuse for internal cabinet overheat, would go a very long way to making it much safer. At least that way, if the fan stopped or got blocked, and the current drain to the spring rose, or the internal cabinet temp rose, it would cut out permanently. Adding a far less flammable liner anywhere the hot spring might contact (like some recycled mica plates from old broken ceramic heater or toaster) would be good too. Or even some aluminum foil to reflect heat away from the wood (but that would add a whole other form of shorting issue).

I think if I made one, I might even just buy a cheap $12 cube heater and steal most of the internals from it to make a very safe low-power low-flow heater in a very nice box by using a 12V fan instead, but still using much of the other existing guts, which will still get slightly warm, but not very much @ 12V and very limited amps controlled by the PWM. And with the right controller, it could be pushed to 200W-300W and be a truly effective small desktop heater too and be very safe.

I do wonder why he did not opt to use a bank of large ceramic resistors as the heating element. They would be very safe, as they can suck lots of amps w/o getting too hot, esp not red hot like an exposed wire spring.

mpikas (author)gregdavid12015-02-01

I agree, ceramic power resistors would be the easiest/cheapest way to do this cheap and fairly safely (you essentially have a ceramic housing around the coil to prevent stuff from catching fire somewhat, and there are a number of sources that people could harvest them from for cheap).

I'd bet that most people would have an easier time finding some sheet metal to prevent direct exposure of the wood to heat, but I'd bet that most people have a few ceramic tiles sitting around (or you can get ones for like $1 each or less at some hardware stores), which would work better and have no chance of causing a short (the only place to find cermaic insulators that you mention that I can think of is another heater...)

PWM would be a very nice way of controlling temp, the only part that I would disagree with is that it would be just as easy to build a 600-800watt heater with it than it would be to build 200-300, just use a cheap controller (you can find them for <$10) and typically 5-60 or more amp SSR's cost about the same (between $10-20 on amazon or ebay), and you could hang the SSR's heatsink in the airstream to both cool the SSR and heat the air. With a 12VDC fan you can use the SSR to control fan speed with temp, so as you increase temp you move more air also...

mpikas (author)mpikas2015-02-01

Huh, the more I think about it the more I think I have the parts sitting around to make a really nice version of this sitting around. I think I have 2 small PWM controllers sitting around, and one or 2 60A SSR's that I have no immediate use for. I'm sure I have some power resistors sitting around, but I also have a pile of nicrome also... I also have a box of scavenged computer fans... I could weld/machine a really cool case for it...

swade11 (author)2014-07-04

does anyone know if you can connect a 12volt car lighter to it?

also could you just do the cooler on a 9v battery?

if yes on both i would love to make 1

LiamOSM (author)swade112014-10-13

9v batteries can't provide much curent. I reckon the heating elemement would try to draw more current than the battery can produce and this would mean the fan wouldn't turn at all. It would be a bust. And a 12v cigarette outlet should be able to provide 30 watts. Just chck your fuse first to be sure.

jmcdonald23 (author)LiamOSM2015-01-29

A cigarette outlet uses a 15 amp fuse in case you want to figure out the max wattage capable.

tensegrity (author)2015-01-29

Aside from the fire hazard issue, make sure the wood is real, untreated wood, not plywood or composite. Otherwise, heating it and breathing the fumes is a great way to poison yourself.

marksstudio (author)2015-01-29

Well done! That's a nice little project and after rummaging around I have many of the parts on hand. Good job, keep going.

j0npae (author)2012-06-27

I live in the US and I tried looking for this thing and I cannot find it. Are there any alternatives to this piece?

xepherys (author)j0npae2015-01-29

I've picked them up through DigiKey in the past:

You could also use a super cheap Arduino mini ($10 or so) and program your own PWM module with a pot controller. Slightly more pricey, but adds to the fun of it (and takes almost no space).

wobbler (author)2015-01-29

I like the look of this design but am I the only person who thinks it might also
make a good firestarter? Commercial fan heaters have a safety cutout if
the fan fails or the temp rises too much. Firestarters don't.

gbankhead (author)2015-01-29

Anyway you'd just sell them on Etsy?

unclejoeyv (author)2015-01-29

Nice. I was wondering what you would do for heat. I have a 69 Chevelle with a rear window defogger. It blows ambient air at the rear window so it doesn't do much actual defogging and zero defrosting. I had initially thought if a ceramic resistor but I don't know much about generating heat safely and this seems like a solid idea.

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