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IR-LED Array

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turel777

New Member
Hi, I'm currently working on my MSc games programming dissertation and the program I'm writing uses infrared light detection. At the moment I'm trying to make a couple of simple 2x2 IR-LED arrays but I have no idea how to lay the, out on stripbaord.

Could anyone help me out with the layout please? I'm a complete noob when it comes to electronics.

I used an LED array wizard to work out what I needed. It came up with this:

Solution 0: 1 x 4 array uses 4 LEDs exactly
+----|>|---/\/\/----+ R = 15 ohms
+----|>|---/\/\/----+ R = 15 ohms
+----|>|---/\/\/----+ R = 15 ohms
+----|>|---/\/\/----+ R = 15 ohms


I'd have to add a switch to this as well. This arrangement is a bit of a problem for me since the layout really needs to be 2x2. Previously I was using a single LED but it wasnt bright enough which is why I want 4 of them arranged in a tight square.

I'm using IR LEDs with a forward vltage of 1.6V, a forward current of 100mA and I'm usign a 3V battery. The site I used was: LED series parallel array wizard


Any help or advice you could give me would be much appreciated!
 

MikeMl

Well-Known Member
Most Helpful Member
In the long run, will you be multiplexing (pulsing) the IR emitters? If so, you could use row/column scheme where each LED is connected at the row/column intersection. This is the way large arrays (eg 10x10) are layed out.
 

turel777

New Member
Nah, I jsut need them to stay on constantly. I'm makign a head-tracking game so All I need is a 2 small clusers of LED (two 2x2 squares shoudl be enough) which I cna place either side of someones head, probably jsut taped to a baseball cap.

Previously I tried to use single IR LEDs in a pair of safety goggles, jsut replacing the original white LEDs. This worked but a single LED wasnt bright enough to be detected at distances of over a meter or 2.
 

MikeMl

Well-Known Member
Most Helpful Member
How long do you think your 3V battery will last if you are drawing 4x100mA?

Why dont you connect the four LEDs in series, then use only one resitor and a higher battery voltage. Much more efficient.
 
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turel777

New Member
To be honest, I have no idea. I'm kinda clueless when it comes to electronics and didnt think I'd need to be doing anything like this in my project. Would having 4 LEDs running on a single battery drain it particularly quickly then? At the moment I'm using 3V watch batteries and I can quite happily add more as needed, I'm not sure what kidna resistor I'd need for 4 in series though. My main problem is I've never made anything using a stripboard before, my first attempt at this is rather large because I've made the whole thing with just segments of wire connecting all the ocmponents
 

MikeMl

Well-Known Member
Most Helpful Member
The battery voltage has to be greater than 4*Vf + the drop across the resistor.
The resistor value = (Vbat-4*Vf)/Iled

A watch battery wont even come close to supplying 100mA, let alone 400mA. I'd go with a 9V alkaline. It will still only last a few hours at 100mA.

(9-4*1.6)/0.1 = 26Ω, so use standard value of 22Ω or 27Ω
 
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