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[Girlinhat]

So I do a lot of bicycling.  Because it's cheaper than caring.  Err...  Cheaper than driving a car.  However it's extremely hot.  So I got one of those little AA-battery hand fans with the foam blades and the little whiny electric motor.

I want something larger, and there's nothing good in town for this sort of thing.  Took me weeks to find this little rickety piece of crap, there's nothing more powerful that doesn't plug into a wall.

And then "Oh yeah I'm totally a Dwarf.  I'll just MAKE this shit!"  So I went down to Radio Shack.  While it seems they're more interested in phones and... phone plans, they do have a corner with several drawers, including plenty of wires, motors, buttons, and other stuff.  I'm not familiar with anything electrical, but the parts are all there and I'm a smart girl.  Starting from scratch, what would be a good way to produce a battery-operated handheld fan?  Preferably no bigger than a 20 oz plastic bottle of soda.

I know there's also metal sheets nearby, in the form of hobby stores.  So one idea was to get a computer fan, a button, and a 12v battery and make a blocky square fan.  I also thought about getting some aluminum cans and cutting them up to produce some metal blades (carefully) and get an electric motor, and put the whole thing into a hollowed out soda can.

Any thoughts on how to do this, or advice on how to solder and wire?  I'm a total noob, never even messed with those "build your own radio" kits, but I'm smart so I can pick up quickly.

[crazysheep]

You might want to consider hooking this up to the bicycle dynamo directly - saves you having to replace batteries constantly, and you get the fan going once you start pedalling.

The computer fan idea might work better than using metal blades. As for soldering and wiring, you'll just need the right tools. Then apply solder to part for soldering and then apply hot soldering iron.

[Girlinhat]

I wasn't actually planning to use the fan while cycling.  I'm pretty coordinated, but both hands on the handlebars!  This was instead for when I stop in the shade to rest my legs a few seconds and cool down a little.  Where I am (Southeaster US) it regularly gets 90+ degrees, heat index 100+ (which means it feels 100+ even though it's only 95).  So frequent stops for water and cooling down are pretty much essential to avoid heatstroke.

[Kilroy the Grand]

So one idea was to get a computer fan, a button, and a 12v battery and make a blocky square fan.

http://www.ceia.ie/pdf/events/circuit_2.pdf
That should give you some idea on how it should work

Any thoughts on how to do this, or advice on how to solder and wire?

All that you need really is a steady hand, and at most a $10 soldering kit from walmart. Hobby stores should sell the good, lead based soldier though, the stuff with silver is much harder to work with.

Make sure both contact surfaces are clean with exposed metal, if the solder beads on the surface instead of meshing the two peices together, try scouring the metal with a knife.

You'll know you've made a good connection when the solder forms into hershy kiss like shape. Don't rush, if you don't have tools to remove solder properly it becomes a huge pain in the ass to clean.

Also watch your hands, you'll probably forget that you're using a 400+ degree sharp stencil. I know I did when I started.

[Greiger]

While not as helpful as the others I will mention something that took me a very long time to figure out until I had it explained to me in a certain way.

The idea of soldering electrical stuff is getting the wiring into a place where the wire makes good contact (like forming 2 wires into small fishhook shapes and then hooking them together and using the solder to sorta glue them in place.)  You don't want to use the solder alone to complete the connection.  For like the first week of class I thought the idea of the solder was to bridge the gap.

Also the best way I found to use a soldering iron is to take the solder dispenser in one hand and the iron in another, keep the iron in contact with the wire you are soldering for a few seconds and then tap the location you want the solder with the solder ideally with the iron still in contact if you have room.  This heats the wire itself to the point where it melts the solder on contact.  Not great for when you have very little exposed contact to work with since you want to be careful not to overheat the stuff around it, but I find it much easier when working with bare wires, and since I have shakes I needed all the help to pass soldering class I could get.

Also messing up isn't a complete failure, you can reheat the solder to re-melt it and try again, you'll probably never get all the solder back so it is still a little messy, but it lets you smooth out the flubbed up areas a bit or reposition a wire that moved while you were soldering, and you can get small amounts to stick to your iron to move it around if you touch it directly.

Disclaimer: I only took a class in soldering as an computer prereq, just throwing some advice out that that was helpful to me.  I've only touched a soldering iron twice outside a classroom, so if somebody contradicts me, they're probably right.

[crazysheep]

I wasn't actually planning to use the fan while cycling.

Hmm.. in that case the batteries are a good idea. Although I'd suggest that if your first try goes well, v2 of your handheld fan could incorporate capacitors for recharging on the go.

[Girlinhat]

If I were feeling very adventurous, I'd probably attach a dynamo to the bicycle wheel so that I could recharge a battery as I was using the bike.  Then just pop the battery out of the wheel and into the fan and enjoy cool air.  But for now I'm looking for a larger-sized handheld fan because this little one isn't doing the job.

The main issue I'm coming with though, is the housing for it.  Any suggestions on what to fit the whole thing into?

[crazysheep]

Soda can, as you first suggested, or the middle half of a 2L plastic bottle (remove top and bottom).

[etgfrog]

yea, plastic bottle probably would be best to prevent potential short circuits...and honestly duck tape would be best to attach it all to the "case"...actually what also works is get a short stick, wire it up to a button or switch, wire it to the fan and tape everything to the stick. the button/switch is so you dont have to disconnect the battery when not using it, have the battery at the bottom of the stick, the switch/button in the middle, and fan on the other end of it, could even run the wires on opposite sides of the stick, something like a foot long stick would probably work best.

[Girlinhat]

I think a 2L bottle would be FAR too big for my purposes.  However, a Gatorade bottle is fairly round and fairly long, as opposed to Coca-Cola bottles which are round, but the round part is short before it gets all curvy.  I just might need to figure out a way to get it all attached on the inside while having it be replaceable.  Chances are the housing will need to be redone every once in a while.

[Mullet Master]

The "Lazy" way to do this job :

1) Since you are not going to be actively charging it when using it, you are going to have to have a storage device. Obviously this is some sort of rechargable battery.
I would recommend using some AA size high capacity NiMH batteries if you are going for long life (high capacity > 2500maH).  It is going to take roughly 6 in series (at ~1.5V apiece) to drive the average 12V computer fan. Realistically battery holders come in 1,2,4.. so perhaps 8 is a good number.
Frankly, I would not worry about making a charging circuit , just charge the batteries at home.

If you are going for extremely easy, two 6V lantern batteries in series is extremely cheap to make but absolutely does not fit into the portable category.

2) Rig up an easy to use switch. I would just a momentary NO (Normally Open) switch. That way, the fan is only on as long as you hold a button and you don't have to worry about leaving it on overnight.

3) If you are worried about a short circuit/battery meltdown, I would consider putting in a fuse. They have these at radio shack, find one that is sized comparable to the fan size. I have a 120mm fan in front of me, it is 12V@.16A. To protect the wires/battery pack, the closest readily available fuse size will be roughly 500ma or .5A.
Assuming 8 2500 maH AA batteries is driving the fan, it should be be able to last well over 10 hours if my calculations are right. In realistic usage, the batteries will self discharge before you actually use their capacity.

Also one more idea : Cut the front out of a lantern flashlight and use it to hold the fan. Cut slots immediately under fan to allow airflow. Stuff batteries into normal cavity. Man, I have thought about this too much.

[Girlinhat]

You have really thought about this too much.  I've already got a little WalMart style handheld fan.  It's an on/off switch, 2 AA's, and an electric motor.  I don't need a fuse for this or any nonsense.  I figure I just need a 12V battery (the square ones that your uncle always tells you to lick), a switch, and a larger fan than "tiny".