Is There Way To Check Infra Red Led In Remote Tv Is Good Or Broken By Analog Meter

EEMajor

Joined Aug 9, 2006
67
Hi.
There are a few ways you can check this. The easiest method is to go to radio shack and by a little card that reacts to IR light, made for this reason. They are a couple of bucks. You point the remote at this card and push a button, if the card "glows" it works.

Second, you can check to see if voltage is being applied to the LED with a meter. This is not a sure check, as the LED may be bad but still getting voltage.

Third, you could use your DIODE check if you have on on your meter for a much more reliable result.

Fourth, if you have no DIODE function, hook your meter in series with your LED and see if it is drawing any current. Again, less of a sure method then number 3 or number 1.

In addition, if you are ambitious, you could build a really simple circuit with a phototransistor sensitive in the IR range, plus a regular LED. When the phototransistor detects the IR signal, it will light up the LED. If no signal is detected, no LED is light up.
 

saint_jay77

Joined Oct 19, 2006
26
The easiest way to check if ir LED is still working is by taking a digital camera and placing it in front of the LED. If when you apply power to the LED with a nine volt batery with a 400ohms resistor in series you should see bright spots on the camera LCD display. If you do see this you know LED is OK; This is by far the most easiest. you might have to align the camera perpendicular to the LED to see something......
 

JoeJester

Joined Apr 26, 2005
4,264
Fourth, if you have no DIODE function, hook your meter in series with your LED and see if it is drawing any current. Again, less of a sure method then number 3 or number 1.
I'm curious as to why measuring the current through the device is an unsure method in your mind. I do realize you would have to take into account of the duty cycle of the pulses which would lower the current "observed" on the meter considerable, if not unreadable. That is the limitations of your meter ... not an unsure method.

I do agree the IR card or the Diode test function are better methods with a GP DMM.
 

EEMajor

Joined Aug 9, 2006
67
I'm curious as to why measuring the current through the device is an unsure method in your mind. I do realize you would have to take into account of the duty cycle of the pulses which would lower the current "observed" on the meter considerable, if not unreadable. That is the limitations of your meter ... not an unsure method.

I do agree the IR card or the Diode test function are better methods with a GP DMM.
You are correct. That is essentially my worry with this method, but if he has the ability to power the LED with a steady source (like the 9V mentioned) then its a good method.
 

kubeek

Joined Sep 20, 2005
5,724
As for the methods, current flowing through IR diode doesn´t make you any sure that the diode emits light, so the best method is number 1, or using IR transistor. The camera trick is also useful, but you have to be sure the camera doesn´t reject IR light - better models usualy have filters to be sensitive only in visible range.
 
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