I go through a lot of LED's and a recent project consisting of over 1000 of the little buggers led me to create my very own LED tester. Now its nothing special. Simply a 3.3v battery which goes through a switch which in turn powers an indicator LED and the LED-to-be-tested through a couple resistors. I tried my best to make it as neat and ascetically pleasing as possible and the following steps and procedures are what resulted from my efforts.
Step 1: Parts and Tools
Here are some of the tools that will be needed:
-Soldering Iron and some solder
-some little pliers and wire cutters to make things easier
-if your feeling fancy you could even use a hobby vice and some magnifying glasses
Parts(including links and prices):
-1 RadioShack 276-159 PCB: $2.49
-1 5mm LED of your color choice(I chose green): $1.50
-Some assorted jumper wires: $6.99 (you can also just make them)
-2 330 ohm resistors: $0.99
-1 CR2032 battery holder: $1.81
-1 CR2032 battery: $3.41
-a small SPST slide switch - I got mine off of a broken radio - but these little guys will work(just snip off one pin): $0.99
-1 2 pin female header: $1.29
-For one tester excluding the jumper wires: $2.77
-For all the parts(you will have extras): $12.48
-For everything: $19.47
Step 2: Solder on the Battery Holder and the First Jumper
First take out the PCB and one battery holder. Position the holder on the board as pictured above - position does matter because it was all done to make the layout as compact and neat as possible. Solder the battery holder in and then grab a jumper or make one that is close to the length of the one pictured. Position and solder that following the pictures as well.
Step 3: Add the Switch and the Indicator LED Resistor
Now solder the switch and the all important resistor in the positions shown above. The direction of the resistor does not matter as it is not sensitive to polarity. The switch simply either allows or restricts the power flow from the battery to the rest of the circuit. So any switch can be used as long as it "switches" that power and of course fits.
Step 4: Adding Another Jumper and the Second LED-to-Test Resistor
Position and solder the jumper and the last resistor as shown above. Moving along............
Step 5: Add the Final Components
Position and solder the indicator LED - remember to keep mind of the polarity as they are diodes and only let power flow one way. The polarity is illustrated in all those note boxes labeling the solder points. Also hook up the 2 pin header, and yellow and red jumpers as pictured above. I hope that the excessive amount of notes on that one picture isn't too confusing. If it is comment below and I will change it.
Step 6: Admire Your New LED Tester
Pop in one of those CR2032 batteries, flip the switch, and your on your way to weeding out those pesky, failing LED's that always irritate the electronics enthusiast. But before you flip that switch remember to plug in your test LED - the anode(longer lead) should go into the side of the 2 pin header that it closest to the switch. Happy LED testing - ENJOY!