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Author Topic: I Built An IR Array That Didn't Work  (Read 14758 times)

Offline matthiasshapiro

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on: February 08, 2008, 07:18:27 PM
I built and IR array with 96 IR LEDs. The LEDs themselved show up just fine when I put them in front of the Wiimote. But I don't think that they were powerful enough to send the reflection back. I've been checking the LED status with my Canon PowerShot SD 1000, which can see the LED's just fine, but wasn't picking up very much in terms of IR reflection.

I was using High Power Infrared Emitting Diodes (Vishay model TSAL6400) at a 940nm wavelength and a 25 degree angle of intensity.

As a test, I checked to see if I could get a good reflection by shining my mini-Maglite forward and video recording the reflective tape on the finger movements. That worked great... my fingers showed up bright and clear with the lights off. I'm going to try using a high-powered IR spotlight(the kind used for nightvision illumination).

I'll let you know how that turns out, but I hope that a post about what didn't work will help out some.


Offline watwerbistdudenn

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Reply #1 on: March 17, 2008, 05:50:47 PM
Hi
how did you connected the leds?
parallel or series connection?

which power supply did you use? voltage?


Offline matthiasshapiro

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Reply #2 on: May 21, 2008, 11:06:31 AM
I connected the leds using a RadioShack breadboard in parallel connection with a 9V battery. I used the LED Array Wizard to configure my array.

(http://led.linear1.org/led.wiz)


Offline Maxx2206

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Reply #3 on: June 02, 2008, 04:12:08 AM
hi,

wat kind of 9v battery was that?
im just curious since 96 leds would drain those standard 9v block batteries in a vers short amount of time unless you limit the current to a very low level. but that would also mean a very low ir emission level, resulting in poor results.

as for the parallel mode... have you wired them ALL parallel and used a limiting resistor or was it a mixed serial/parallel drive to avoid the resistor? what was the real led current in your circuit?
most ir leds state standard operation at 20mA, but at a relatively low emission rate. 50mA - 100mA is usually where they really shine bright, but that's a real battery killer and you should instead consider using less leds+reflectors+higher current for better results.


Offline Caio

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Reply #4 on: June 26, 2008, 10:24:23 AM
I had the same issue here, but I used 3V with one LED.

The LED drained up all battery after some seconds I think the same happened there.


Offline s1ay3r jo3

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Reply #5 on: July 02, 2008, 02:20:27 PM
I think what is being said that may not be obvious to persons not electronically inclined is that to power 90 LEDs in series would require a huge amount of current. Since there is a voltage drop over each LED, the current through the total circuit would be very low from a 9v battery. Maybe that is a poor explanation, but the point of it all in the end is that parallel circuits are necessary. For that large number of infrared sources multiple power sources may be required or transistors to amplify current. i would recommend multiple rows of 10 LEDs in series. Then put all of these series in parallel with each other. Your source is still over-kill. I am wondering if pet heat lamps would produce the right frequency to be used with a wiimote. Perhaps a shiny aluminum bulb reflector could be used with a 60W lightbulb and simply shone in your desired direction?


Offline s1ay3r jo3

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Reply #6 on: July 02, 2008, 02:26:01 PM
this type of configuration would work great- you can put the LEDs in any orentation, but connect them like his schematic shows. http://undcon.com/mods/irarray/


Offline matthiasshapiro

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Reply #7 on: August 10, 2008, 04:36:40 PM
s1ay3r jo3: I didn't wire it in a series, I wired it parallel. Therefore the power drain wasn't nearly as bad as it otherwise would have been. The 9V battery was able to power it for about 5-6 hours. The problem was that the reflective tape wasn't reflecting enough IR light to pick up.

I ended up using gloves with IR LED's attached to the fingertips and thumbs. In my opinion, this is a way better solution. It's much less finicky than the IR Array/reflective tape approach. And cheaper.


Offline Ringer

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Reply #8 on: August 26, 2008, 05:16:38 AM
Has anyone managed a plug-in power source? I tend to electrocute myself anywhere near a wall socket, and especially now that I live in Europe (220 V; ouch) I'm not doing it until I know what I'm doing.

UndCon, you mentioned using an old router adapter/cord for AC to DC, right? Notes?


Offline UndCon

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Reply #9 on: August 26, 2008, 06:28:05 AM
Yes I have an 220V adapter

output is 12V 450mAh... I think it can be more...My Array is a bit weak...


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