What do you do when you have a lot of time on your hands, a whole case of “Altoid” style metal boxes for a project that never came to fruition, and a bags full of surplus electronics parts? If you’re me, you end up with stuff like this:
So I was sitting around this morning staring at all this stuff on the shelves down here in my version of a mad scientist’s laboratory (I’m not really mad, only slightly eccentric.) wondering what I could do that would A) kill time because dear lord I was getting bored (so, sooo bored) after being in self imposed exile for weeks, B) be really, really cheap, C) be fairly easy to do because even though I was bored, I’m also lazy, and D) use up some of the junk I have laying around like that bag full of weird little switches. So there I was with a bunch of small metal boxes, a bunch of LEDs, a bunch of switches that aren’t good for much of anything, at least not for anything I normally tinker with, and I started thinking – ooo, it’s lunch time, let’s go eat.
But after lunch I thought hey, there is no such thing as having too many flashlights, is there? I mean whenever you need a flashlight either you can’t find one, or the batteries are dead, or someone took out the batteries to stuff in the remote for the TV or to power a robot or weather station or something. Even better, maybe MrsGF might stop wondering if she needs to call someone about my “problem” with accumulating various parts and gadgets and similar stuff if I actually use some of this stuff to crank out something remotely useful.
(Sidenote: LEDs are a lot of fun to play with, and cheap to boot. A few LEDs, some resistors, a 555 timer, a few transistors, maybe a microcontroller, and you too can have a lot of fun building really cool and utterly useless little gadgets)
So first I need a 3V power supply of some kind because the LEDs I got want to be fed about 3 volts. AA batteries work well for this. (So would AAA batteries, BTW) Two AA batteries together will put out 3V so… Oh, I didn’t have a battery holder thingie. Ah, well, no problem there. Just solder the suckers together. Solder the negative pole of one battery to the positive of the other with a hunk of wire, solder jumper wires on, and away we go. Instant battery pack.
Is this safe? Um, maybe? Probably not? Is it easy? Not really. It’s a pain in the neck. Solder doesn’t want to stick to those suckers. (Hint: scuff the surface of the battery with fine sandpaper. Seems to help the solder adhere.) But this is a doomsday flashlight, remember? You don’t need neat and tidy and professional looking, you just need something that works. Jury rigging is encouraged.
Speaking of jury rigging…
What about actually making some light? That’s the easy part, really. A couple of resistors for current limiting, a couple of LEDs, and away we go.
Now for mounting the LEDs in that case. How the heck do we do that? I don’t have any of those fancy mounts… Well, we’ll just drill some holes just barely big enough to shove the LED through and add lots and lots of glue.
Now, to sort through this lot to find a switch that might work…
The problem when you buy bulk lots of stuff labeled “100 Misc. Switches, $1.99” is that the chances of you getting anything actually useable out of that lot is pretty slim. Still, we work with what we got. All of those are momentary contact switches that stay turned on only as long as pressure is applied to them, and they aren’t really suited for what I want. Unless… Ooo, I know! Use the lid of the case as the switch. Close the lid it puts pressure on the switch and turns it on. Open the lid and it turns off.
And this is what I ended up with. LEDs glued into holes drilled in the end of the case. Lots of plastic tape to insulate the wires. The batteries wrapped in tape and held in with a self adhesive velcro pad, and the switch glued to the top of the battery conveniently makes it exactly the right height to turn on when the lid is closed. Damn, that was lucky there because otherwise I had no idea how I was going to mount that switch. Ooo, can you say serendipity?
And, damn, it actually works??? Yeah, it does. Closing the lid puts enough pressure on the switch to turn it on. Open the lid and it turns off. And puts out a surprisingly large amount of light, too. Damn, I actually made something useful? Wow!
It also uses very, very little power. I put it on the meter and it draws about 0.005 amps. A set of AA batteries will probably keep this thing going 24/7 for a couple of weeks. Which is good because changing the batteries in this thing would be a royal pain in the neck, them being soldered in like that.
Total cost on this, excluding the batteries, is maybe a buck at the most? Most of this stuff like the LEDs and the switches were bought in large lots as “surplus” in a moment of weakness when I was scrounging around on-line. (“Ooo, that’s a real deal! I’m sure I’ll need 1,000 miscellaneous LEDs in the future”) It took maybe half an hour to put it all together, and it only took that long because I’m easily distracted. And because it took me 10 minutes to find a roll of electrical tape.