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Picture of Desk fan/heater
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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.

 
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Step 1: Materials and tools

Picture of Materials and tools

Materials:

  • 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

Tools:

  • 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
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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).

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crashzoom3 days ago
Very cool.. I have ordered a fan from eBay but it is too weak to fit this project
phillipcd22 days ago

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

MichaelS381 month ago

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.

mpikas1 month ago

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).

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.

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 mpikas1 month ago

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...

gregdavid11 month ago

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.

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swade118 months ago

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

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.

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

tensegrity1 month ago

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.

marksstudio1 month ago

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

ArthurOwen1 month ago
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.
Spokehedz2 years ago
Link to where you bought the PWM dimmer module?
HHarry (author)  Spokehedz2 years ago
(removed by author or community request)
j0npae HHarry2 years ago
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 j0npae1 month ago

I've picked them up through DigiKey in the past: http://www.digikey.com/product-search/en?KeyWords=...

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).

HHarry (author)  j0npae2 years ago
Would this dimmer switch work instead? It isn't labeled as PWM

http://www.ebay.ca/itm/120782777352?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649
HHarry (author)  octochan2 years ago
It is really a pity my supplier won't ship outside Europe, it is really a good product. If you are just going to use the fan the dimmer you mentioned (I think) will work. But with the heating element installed the dimmer will burn down. You should calculate how much amps all your components need and than buy a proper pwm controller, but don't spend to much money on it. On ebay type pwm controller.  Here is a similar product http://www.ebay.com/itm/12V-40V-24v-36v-3A-Pulse-Width-Modulation-PWM-DC-Motor-Speed-Control-Switch-/110888220149?pt=LH_DefaultDomain_0&hash=item19d173f5f5  
wobbler1 month ago

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.

gbankhead1 month ago

Anyway you'd just sell them on Etsy?

unclejoeyv1 month ago

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.

parkmana2 months ago

Those 12v car lighter have a heating core made of NiChrome (Nickel/Chromium) wire. Less amps, more heat.

jdmumper2 years ago
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... http://www.amazon.com/TEC1-12705-Thermoelectric-Peltier-Cooler-40mm/dp/B002UQKEU8/ref=pd_sxp_f_pt
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..
Liam.great985 months ago

how much heat does this produce? I tried a proof-of-concept without the fanc wooden enclosure and the spring was drawing about 5 amps, that's 60 watts, but when the fan blew on it it just cooled it down and barrly any heat was actually blown out by the fan.

Nhoj161 year ago
This is really cool, I'm going to make one for my mom who hates the cold. So not to overcomplicate it can I just hook a computer fan and hair dryer coil to a 12v cord?

I would assme a hair dryer coil is designed to run on mains power (120/240vac) so connecting it to 12v will produce minimal heat.

Peter8802 years ago
UK PWM Fan Controller
http://www.shinyhardware.co.uk/prods/showprod.asp?pid=18732

Cheap and decent, I bought one ages ago.
Schmidty162 years ago
man i love the look of it i wish i could make one i will try someday
If 30 watts is working for you, that's great. My experience with portable electric heaters is that they are usually rated around 1500 watts, maybe with a "low" setting of 750 or 1000 watts. I've used a ceramic-element heater which, once up to temperature, would settle down to 400 watts on its "low" setting. This was barely enough to keep a small room warm.
HHarry (author)  RankineCycle2 years ago
Yes, I know It just gives a warm stream of air nothing more nothing less. Just like I said in step 5.
Finally, a project that interests me enough to build. Only thing that concerns me is the safety aspect of it. When I build mine I'll put a couple more of safety features in it.
NightLord2 years ago
Well if you want more heating power, just add some more springs in paralell... just be careful it doesn't heat too much.
scottinnh2 years ago
Congratulations on a polished product and documentation.

Your drilling was perfect not just with pattern spacing, but also for smooth bore holes. Wasn't till I saw the close ups that I could tell it wasn't laser cut.

I'd suggest to anyone else that they clamp a piece of sacrificial board to the front faceplate, to avoid splintering when the drill bit punches through.

Other suggestion is to skip the heating element and buy the right sized 12v light bulb... An incandescent bulb is a heater, light, resistor, and safety fuse all in one.
Yeah, but then it is icky nasty incandescent light blasting out of the vent holes and you wouldn't be able to see the LED.

Also with those long power bus bars you could easily add one or two more springs in there to get a little bit more heat blowing through. Plenty of space in there, but obviously the power requirements go up.

GREAT JOB!
rickharris2 years ago
I might suggest that some nichrom wire would make a better heater element. The spring is likely to fatigue or just burn out .

I would suggest a sensible fuse in the circuit is a good protective device in case of excessive current.

Is putting a heat source (30 watts is quite a lot) in a wooden case advisable?
HHarry (author)  rickharris2 years ago
The spring does not burn down; the fan keeps everything cool. You can see it as a hair dryer: 2000 watt in a confined space still the hair dryer does not melt down.
My design is like putting a 30w light bulb in a open wooden box with a fan on it.

But yes nichrom wire would be a better option. Also a tilt switch is advisable so everything shuts down when the box is putt on his back.
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