Handy Dandy Flashlight





Introduction: Handy Dandy Flashlight

About: I'm entirely self taught in electronics, although I do have a chemistry degree which I currently don't use at all in my day job but that's totally okay! Currently studying robotics, Arduino, microcontroller...

Are you one of those electronics hobbyists who always has a bag or two full of "goodies"? I built this flashlight from spare parts in my room. Why? Because it was a Sunday afternoon. That's why.

Total project time was well under an hour, including thinking "Hey, I want to make a flashlight" and "I wonder if I have everything on hand to make one."

Even without the wrist strap, it's great for slipping in your pocket - just in case it's needed.

Apparently I have to write something in bold stating that this is in the Pocket Sized contest in order to get any votes. I've noticed that all the Instructables that do this get a heck of a lot more votes than this one, even though I was the second or third to enter the contest. Please vote! Maybe if I keep writing I'll get more votes than other flashlight projects basically identical to this one that were posted after mine.

Step 1: The Parts

This was made with:

1) four 17,000 mcd clear white LEDs
2) one 10 ohm resistor
3) one tiny SPST switch
4) some perf board
5) two AA battery holder
6) two AA batteries
7) mounting tape, although hot glue works better

Naturally not everyone is going to have super bright LEDs just laying around their room. You can use any bright LED you want, but the brightness will be different.

Step 2: How It's Put Together

1) Orient each LED in the same direction and solder them in place. Connect all of the positive leads together and all of the negative leads together.

2) Solder the resistor and switch in place.

3) Solder the red lead from the battery connector to one side of the switch, and connect the other side of the switch to the resistor.

4) Connect the other end of the resistor to the positive lead chain of the LEDs.

5) Connect the black lead of the battery connector to the negative lead chain of the LEDs.

6) Mount the perf board to the battery holder. I used some mounting tape, although hot glue would hold it much better.

Step 3: But Wait, There's More!

If you'd like to try your hand at sewing, you can make a cool wrist strap for your little flashlight. I've been watching a lot of Star Trek Voyager recently and noticed that they always have flashlights strapped to their wrists on their away missions. I wanted one too!

This was made with some webbing and Velcro. After a quick tutorial about how to use a sewing machine, I tried my hand at it. Came out pretty well. The little pocket was made by folding some webbing together lengthwise and sewing the sides together.



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29 Discussions

Obligatory current limiting resistor nitpick:

If you put multiple LEDs in parallel, then each will need its own resistor - having a single resistor for a bunch of parallel LEDs does almost nothing.

In this case, you're probably OK, since the two AA batteries actually supply a lower voltage than the typical forward voltage for your LEDs, and you're losing another whopping .8V across that 10 Ohm resistor. You may get very uneven light from your LEDs though, if one of them has a much lower forward voltage than the others (e.g. Min = 3V versus Max = 4V).

If you're going to go through the trouble of sewing a wrist band for this, might as well get the electronics right too... ;-)

4 replies

woohooo I think on every single LED instructable someone mentions something amount the resistor or something like that. But yeah, you might wanna check that resistor out.

You're right. I got lectured on the last LED type project I posted too. I know it's done in the spirit of helping out, but c'mon.

I can honestly say putting them in series may do other things. I used a 9.6V NiMH battery to power 8 LEDs in series, no resistor (I was stupid back then), but it didn't burn them out, and they were bright enough to use.

This can be easily remedied by putting the LEDs in series rather than in parallel. Since the resistance of a diode drops to almost nothing once it's on, you can put a whole chain of them in a row, negative to positive, and they'll work just as if they were in parallel. Hook that resistor in at the beginning or the end of the chain and you won't have any problems.

this is a great idea!. what would make it even cooler is if you added a momentary switch instead of the SPST,and 1) had it under the batterypack so that the leds would light up when you flexed your wrist or (2) on your palm so the lit up when you pushed your fingers into your palm. (i like #1. less spiderman-like)

Hehe I did this when I was in the Army back in the 90's...great 'ible tho cant wait to see what else you come up with

dude this is exactly like I need for work nights at the farm; i could totally impress every one there! :~)

Eh, you probably don't know me, but I'm Mario on the forums. (Didja hear I'm making a portable NES? I'll be posting the how-to on here.)

I like it, although, i cant stand the feeling of webbing against my skin, so i will probably make my wrist band out of leather

Oh, I'm totally going to try this. I need hands-free flashlights on my job when I have to change a tire in the middle of the night.

It looks like a definate build i just dont think i have the parts

I'm gonna make this and blind my freinds with the power of 4 ultra bright LED's muhahahaha. I might add more batteries like mabe 4 parrallel AAA's to make it last longer.

This rates a definite "WANT" on my rate-O-meter. I'll try to make this spring break. Fave'd, +1'd, and voted for.