Testing LED Specs??? - diyAudio
Go Back   Home > Forums > General Interest > Everything Else

Everything Else Anything related to audio / video / electronics etc) BUT remember- we have many new forums where your thread may now fit! .... Parts, Equipment & Tools, Construction Tips, Software Tools......

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 20th December 2007, 07:44 PM   #1
diyAudio Member
 
Zero Cool's Avatar
 
Join Date: Sep 2004
Location: MN
Default Testing LED Specs???

With My recent playing with some LED's i have discovered i have a large box of unknown LED's on hand. Making them light up is easy enough, but is there a way to test them to figure out what the voltage and current should be without blowing them up??


Zc
  Reply With Quote
Old 20th December 2007, 08:01 PM   #2
diyAudio Member
 
I_Forgot's Avatar
 
Join Date: Jan 2005
Location: Phoenix, Az.
The vast majority of LEDs are spec'd to run at 20 mA. Make a 20 mA current source and measure the voltage drop across the LED if you must, or just assume about 2V for red and maybe 3.5V for blue and green.

I_F
  Reply With Quote
Old 21st December 2007, 11:18 AM   #3
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Hi,
a 9V pp3 battery + 2k2 resistor + LED + Multimeter + some wire = full testing kit.

If you want to test at various currents then substitute alternative resistors.
__________________
regards Andrew T.
  Reply With Quote
Old 21st December 2007, 12:17 PM   #4
diyAudio Member
 
Zero Cool's Avatar
 
Join Date: Sep 2004
Location: MN
I cant light the diodes easy enough. but what i want to know is how to measure what there rated voltage and currents are supposed to be.

Looking up LED specs i see that there are a lot of choices depending on brand and model etc.

I have 3 or 4 different types of T-3/4 Red leds. some are 2.1V some 5V some 12V and some are weird 1.2V an the currents seem to be all over the place as well. some 20ma or so some 30 one is 50 and some are 5ma.


I just thought there might be an easy way to measure and figure it out.
  Reply With Quote
Old 21st December 2007, 04:22 PM   #5
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Hi,
any LEDs that need 5V or more, incorporate a driver circuit. They are no longer LEDs.
I have never heard of a 1.2V LED.
Most LEDs are in the range 1.5V to 4V and need external current limiting.
You can easily measure the Vf using that test equipment.
Run @ 2mA and see how bright they are. Try 5mA and if it burns out then that was too much.
__________________
regards Andrew T.
  Reply With Quote
Old 27th December 2007, 08:45 AM   #6
suvatn is offline suvatn  Thailand
diyAudio Member
 
Join Date: Jan 2006
Location: Bangkok
http://www.ledtronics.com/datasheets...r_chart/38.htm

The chart from this link may help you some.

Led have several types, colors and development are very fast.
Basis, normal foward voltage will 1.x to 5.x
If you put constant current 20 mA, measure Vf, see color, see
how bright.
You may find it.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
ADC specs percy Digital Source 10 12th January 2008 02:18 PM
MS 5.30 Specs Inductor Multi-Way 0 4th September 2007 09:37 AM
THD specs gndpoints Instruments and Amps 8 25th April 2005 10:24 AM
sub specs l2z2ama Subwoofers 2 13th November 2003 12:41 PM


New To Site? Need Help?

All times are GMT. The time now is 03:31 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2