Picture of LED Altoids Tester
Altoids LED Tester with 2x AA Batterysupply made of old IDE Cable

Tools you need:

Altoids Gum Tin
Soldering Iron
wire cutter or caliper
Battery Clip for 2xAA batteries
2 AA batteries
1 old IDE cable

20min of your life ;)

By the way.. I was inspired by this awesome Instructable:


Step 1: Find empty Altoids Can

Picture of Find empty Altoids Can
I like the size of this one because it fits 2x AA batteries pretty well.
Besides the gum tastes delicious.
*But don't eat all at once..*
127ice1 year ago
I can't figure out what it is you will be testing.
diyworkbench (author)  127ice1 year ago
You can test if the leds you have laying around are working or not without having to solder them together
leotcol5 years ago
The majority of my LEDs are about 3.1 and 3.2 Volts so this would be perfect.

But I do have some like the yellow, orange and red ones that are about 2.1 -2.4 Volts

Maybe if I make this I'll include a switch for supplying either 2 Volts or 3 Volts.
Just need to add a resistor and a bit of wire and a switch as far as I know.
diyworkbench (author)  leotcol5 years ago
just adding a resistor should do. since its just for testing the 3v LEDs won't be so bright with a higher resistor but you can cover almost any led for testing then..

actually i made a joul thief for testing.. that works with just one battery.
John H Doe5 years ago
For step 3 you don't really have to solder, you can use a strand of the wire you took the plastic out of and push it into the little pins. If you use a knife to push the cable down further into the pin you get a more secure connection.
diyworkbench (author)  John H Doe5 years ago
thanks. great idea.
skoolerror25 years ago
what is this for any way
diyworkbench (author)  skoolerror25 years ago
Simply to determine if your led works or not. But I made a better one using a joul thief to use just 1 AA battery for a quick check.
guyfrom7up7 years ago
nice, but you should throw in a resistor somewhere.
diyworkbench (author)  guyfrom7up7 years ago
Thanks. I think I don't need a resistor for testing, plus it's only about 3V. Most of the LEDs (exept high power LEDs) work at about 3V. The blue one is not as bright as it could, but it will work. Correct me if I'm wrong ;)
well, usually voltages: Red - 1.7 Bright Red - 2.0 yellow - 2.1 Green - 2.1or 2.2 blue or white - 3 volts or more (depends a lot) tell me, am I being mean? Ever since some of my instructables this one guy has been leaving super mean comments to me, and sometimes he right, but explodes stuff out of proportion, such as my sound reactive led instructable, saying I did everything wrong and insulted me, made me feel really bad. Even though I did adress all the stuff he said in my instructable...
not sure what ur talking about cuz most of the leds i have (red,yellow,green,blue) work between 3 and 6 volts
In my country a super-bright LED draws 20mA and used 3.3v while a normal LED draws ??mA and uses 9.3v. Weird, or what?
however,all leds work safely upto 3 volts.
diyworkbench (author)  guyfrom7up7 years ago
no sweat. I don't have my master in electronics.. so I do like people telling me what to improve. I think that's what instructables is for.. so thanks for your advice. What resistor do you suggest?
i would personally suggest (if you make a new one) to put a current regulator regulated @ 5mA. most L.E.D.s work at 20mA, but there are exceptions, like 5mA and 3mA and sometimes, more, but that is the most common. 20mA L.E.D.s @ 5mA are still bright and 5mA L.E.D.s are as bright as they go... 3mA L.E.D.s would be in a bit of a risk (very very little) and you do it for a little bit of time, 2 or 3 seconds, since its a tester... i personally suggect the LM317 current/voltage regulator, 'cause its really easy to use. if there are any questions about what i said, dont be shy to ask. -gamer ps. very nicely made instructable!
diyworkbench (author)  gamer7 years ago
thanks. I think i prefer the regulator instead of the resistor.. cause you never know the exact voltage of the LEDs (I have a jaw with leds soldered out of various things e.g. printer, keyboard.. everything i could get my solder iron on )

I have to make shure the 20mA are still bright - as you said.. would be sad if you can barely see anything like the LED tester on my Multimeter..
a 20mA L.E.D. at 5mA is very bright concidering it is using 1/4 of the mA's needed. do your tests and tell me your results, but i do know i got great results... anyways... good luck -gamer
You can calculate it:
R = (U - Uled) / I
R is the resistance
U is the voltage from the Batteries
Uled is the voltage the LED needs
I is the current the LED needs
in your case: R = (3 - 1.7) / 0.015 = 1.3 / 0.015 ~ 86 Ohm for a red LED.
mfg Daniel
diyworkbench (author)  homunkoloss7 years ago
thanks. it's not that i don't know how to calculate it, but how much do I need...
maybe your example makes sense, cause it's almost the lowest LED Voltage it could get..
I'll see if I open it up again someday to keep the nice altoids tin
and then decide to put either the regulator or the resistor in the circuit.

.. by the way.. here is a sweet online calculator: http://ledcalc.com/ VERY useful
isnt it R = (V-Vled)/I.
thats what my father thought me, please correct me if im wrong.
U is the Symbol (Probably not the correct word but my English is not so good) V is only the Unit mfg Daniel
diyworkbench (author) 7 years ago
Thanks. That's just colored hot glue to get the IDE connector and wires stay fixed in the case.
agis687 years ago
looks good, i will make one for testing all my leds, but a question: What is this red thing you surround the tranfer cable?
dr_pepper7 years ago
yeah a resistor would help just in case
watch out the leds will pop if u dont put in a resistor (just in case)
Really smart idea. And, you actually should add in a resistor, even if it's a little resistor, it could help a lot, and be a help. Awesome job!