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 LED Light testing How-to & Homemade testers
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Author Previous Topic: Flexible Track Power Indicator Topic Next Topic: DCC Engine Wiring Question  

desertdrover
Engineer



Posted - 03/19/2018 :  3:42:41 PM  Show Profile  Reply with Quote
There are many questions from Forum members on how do I test an LED. Here are four (4) How-to ways to accomplish this task. Depending on your needs or skills these are some pretty simple ways to get the job done. Starting 1: with a Digital Multimeter, 2: using 9 Volt battery with 1K Ohm resistor in-line homemade tester, 3: using two (2) double A batteries, or 4: a nifty little gadget from Ngineering using a Nine (9) volt battery with a circuit board with installed resistors for testing LEDs.
Starting with the use of a Digital Multimeter, connect the Black test lead to the COM jack and the Red test lead to the Note that the polarity of the Red test lead is +).
Set the meter Function switch to the range (see picture below) and connect the test leads across the diode/LED. If the LED does not light, switch your red and black leads on the LED. When the LED lights whatever black lead clip is on your LED leads will be your (-) Neg. Cathode lead and that is where your resistor will be placed when installing into your Locomotive, Rail Critter, Structures or any LED lighting situation.



Second method using a homemade 9 Volt battery with 1K Ohm resistor in-line homemade tester. Get a set of red and black wires on a 9 volt battery snap on clip, and place an LED holder, or red and black alligator clips, on the other end of the red and black wires. Place a 1K Ohm resistor in-line on the black wire. To test an LED, place the LED into the LED holder, or use your alligator clips, and again if it lights, note what lead the black wire goes to on the LED leads, and that is your (-) Neg. Cathode lead and where your resistor is attached.



Third method using a double A battery case with two (2) double A batteries homemade tester. Attach a set of red and black alligator clips to the battery case red and black wires. (No resistor needed for this tester) Connect your LED to the tester clips and again, if it lights, note what lead the black wire goes to on the LED leads, and that is your (-) Neg. Cathode lead and where your resistor is attached for when you install it into your locomotive decoders White (Forward) or Yellow (Reverse) light leads.



The last LED tester is a device made by Ngineering, Part #N8021, for testing LEDs, nothing more than the same as your homemade second tester using a nine (9) volt battery and resistor. This device already has a resistor installed into a circuit board with nice convenient attachment clips for your LED leads. And same as all the other testers, the black lead shows your (-) Neg. Cathode lead and where your resistor gets attached prior to installation.


Country: USA | Posts: 17348

Bill Gill
Fireman



Posted - 03/19/2018 :  4:47:52 PM  Show Profile  Reply with Quote
Thanks, Louis. Should be a method there for pretty much everyone to use.


Country: USA | Posts: 2314 Go to Top of Page

Ensign
Fireman

Posted - 03/19/2018 :  5:57:04 PM  Show Profile  Reply with Quote
Louis, a very thorough listing of different ways to test LED's, thanks for taking the time to post this for everyone's benefit.

Though... you did leave out the "Fester Tester"





Greg Shinnie



Country: Canada | Posts: 7721 Go to Top of Page
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