Author Topic: What am I doing wrong?  (Read 5791 times)

Offline micbridge

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on: April 02, 2008, 07:15:52 PM
I've got two AA's in a pen in series. I know juice is flowing because it lights up an incandescent flashlight battery great. I have the very Vishay 6400 IR LEDs That are recommended. I have a 1/2 watt 16 ohm resistor on the positive side of the LED. I know power running through the LED because I can feel the heat after a few seconds.

After so much tweaking and fabrication I feel disappointed. Is the problem the 1/2 watt resistor?



Offline UndCon

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Reply #1 on: April 03, 2008, 06:56:50 AM
Try using the ledcalculator

http://ledcalculator.net/

To verify your IR's you can point it at a digitalcamera, webcamera or even handycams
and watch the display to see if your IR turns on or off

If you know your batteries are ok and LED doesnt light up it might be destroyed or there is a problem with the circuit



Offline micbridge

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Reply #2 on: April 04, 2008, 04:06:43 AM
Thanks for the advice. I was able to obtain a few 10 ohm 1/4W resistors yesterday. I'll have a chance to try them out tonight. I hadn't thought to test it on some receivers.



Offline UndCon

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Reply #3 on: April 04, 2008, 08:54:26 AM
well - it doesn´t hurt using a resistor...



Offline micbridge

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Reply #4 on: April 04, 2008, 11:19:12 AM
I soldered in the 10 ohm resistor on the positive lead of the LED and put the power through. No dice. Figuring the LED calculators all say 15 Ohm I soldered another 10 Ohm resistor in series off the original 10ohm to equal 20 ohms, power, and... no dice. Not a flicker. I then soldered the leads to an incandescent bulb to check power and it lit up. Is the 15ohms just so important? If so I'll go ahead and order them online. I'd like to see a light first before I do it.

Can one of you describe your experience with a Vishay 6400 IR LED and tell me how many of type of battery you have in series, what kind of switch you used, type of resistor including ohms and watts, and what lead (positive or negative) you put the resistor? This might help me understand what I'm doing wrong.

I've hooked up electronics together before, in specific AA's and flashing LEDS and lasers together with no problem. I just can't get the IR LED to light like it does on the Johnnie Lee video, just looks blank.

All comments and help gratefully received. Thanks.



Offline micbridge

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Reply #5 on: April 06, 2008, 04:01:40 PM
I tried using my camera to "look" at the IR LED turned on. I just found out that I had the hook up right all along!! The LED lights up on the camera screen. That also explains why the LED lights up in Johnie's video; he used a digital camera too. You cannot see the IR light up when powered with your naked eye. I am now finalizing my AA and AAA pen versions and moving on to the Wiimote-computer hookup. I'll post my pens when completed.



Offline UndCon

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Reply #6 on: April 07, 2008, 02:52:20 AM
I'm glad you sorted it!

there are some electronic kits you can buy to test IR-led's but why spend money on something like that when most ppl have digital cameras, camcorders and other usable sources at home (might even work with a cellphone but min has no camera so I cannot try right now)



Offline Smokeduv

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Reply #7 on: April 17, 2008, 01:04:50 PM
Yes, it works even with cellphones with camera, hehehehe. You can even use it as a night vision camera with an IR array and a cellphone, camera or whatever digital camera you can find ;D, it will work even with all the lights gone, zero light (visible, of course, because the IR is some kind of light :P)