IR shaft encoder

hgmjr

Joined Jan 28, 2005
9,029
Two major reasons for irled not to illuminate.

- irled polarity incorrect
- failed irled

Focusing on the emitter section for a moment, try reversing the connections on irled and then see if it illuminates. I should light in at least one direction if it is good.

hgmjr
 

hgmjr

Joined Jan 28, 2005
9,029
Yes. That is what I mean.

Can you get it to light in at least one direction when viewed through your digital camera?

There should be a slightly flat side near the base of the LED lens. That is usually an indication of the cathode. The cathode is the terminal that is the negative terminal.

hgmjr
 

Caveman

Joined Apr 15, 2008
471
you mean light from IRLED???as white light??
What they are trying to tell you is to just make sure your IR LEDs are working first. Since you can't see it with your eyes, you should use a digital camera to see it. It will show up as a spot on the image.

Try the camera thing again, but this time look directly down on the part. When you look at an LED from the side, you will get very little output.
 

Thread Starter

h.d

Joined Oct 22, 2007
150
ok,
i know which the anode ad cathode........and turn it to test......capture 50 pic....
no light from IRLED....so from last the IR LED should be dameged....also i tested 4 IR LEDs

thanks for all,,,,
 

Thread Starter

h.d

Joined Oct 22, 2007
150
know no....i will bring it today.....but if the IR is dameged why the output change when i make my hand near the IR LED???
so there are a change...but not enough voltage...
 

hgmjr

Joined Jan 28, 2005
9,029
know no....i will bring it today.....but if the IR is dameged why the output change when i make my hand near the IR LED???
so there are a change...but not enough voltage...
If you are refering to placing your hand near the receiver IRLED, then you may have touched the high-impedance terminal of the opamp and that together with the high open-loop gain of the opamp was enough to cause a change in the output of the opamp.

hgmjr
 

Thread Starter

h.d

Joined Oct 22, 2007
150
i attach the photos of the test....there are no light...i dont know if its a high or low ligh....soooo i confused....:(:)
 

hgmjr

Joined Jan 28, 2005
9,029
OK. Let me make sure that I am crystal clear on where things stand. You have taken all of your IRLED's you have and tried them one at a time in series with a current limiting resistor and found all of them to be bad. Am I correct in my understanding?

You do know that it is a bad thing to apply DC voltage across an LED without a series current limiting resistor, right?

hgmjr
 

Thread Starter

h.d

Joined Oct 22, 2007
150
know its 3 am in my country.....so i need 12 hours to get a new IRLEDs and work agian...
i take alot of your time.... thanks alot for you.....but its the info.....will back with new IRLED....ask the god to bo good.thanks again.
 

hgmjr

Joined Jan 28, 2005
9,029
So at least now you know you have working IRLEDs.

Keep in mind that the IRLEDs are highly directional so make sure that the LEDs are oriented so that they are pointing at each other.

The distance over which the IR link will operate is going to depend on how much current you are using in the emitter IRLED and how much sensitivity you have on your detector circuit.

From what you are telling me I gather that you are now confident that you have working IRLEDs but that the emitter is not being detected by the receiver. Am I correct?

hgmjr
 

Thread Starter

h.d

Joined Oct 22, 2007
150
So at least now you know you have working IRLEDs.

Keep in mind that the IRLEDs are highly directional so make sure that the LEDs are oriented so that they are pointing at each other.

The distance over which the IR link will operate is going to depend on how much current you are using in the emitter IRLED and how much sensitivity you have on your detector circuit.

From what you are telling me I gather that you are now confident that you have working IRLEDs but that the emitter is not being detected by the receiver. Am I correct?

hgmjr
yes.....that correct...the sender is worked but no answer from the receiver
 
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