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RSS >  Keep frying IR leds. Help!
stubborn #1 05/04/2009 - 16h11

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I know nothing about electronics. I just want to build a funny 3 point cap to check games out. I hope you can give me some good advice.

The only reference they had in store about the leds I was given is "CQY99". So I checked online and found this:

http://www.datasheetarchive.com/pdf-datasheets/Databooks-3/Book518-398.pdf

http://www.datasheetarchive.com/pdf-datasheets/Databooks-5/Document24088.pdf

I was also given three 10 Ohmns resistors at 1/4 w.

I currently use 2 rechargable batteries 1.2v each.

If I use one single point setup, it all seems to work fine, but as soon as I try the 3 point setup, 2 leds burn and I remain with just one (this happened twice already).

I think I have also noticed that with more than one point setup the leds heat up a lot.

What am I doing wrong?

Thanks fellas :)
Fanboy1337 #2 05/04/2009 - 17h22

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u r using a parallel setup for ur LEDs?

are the batteries in row (2.4 V total)? or parallel (1.2 V total)?

i am no expert myself but maybe i can help
Kind regards from Germany.
Setting up my Freetrack for www.jumpgateevolution.com
stubborn #3 05/04/2009 - 17h39

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Fanboy1337 @ 05/04/2009 - 17h22 a dit:

u r using a parallel setup for ur LEDs?



Yes. 3 leds, 3 resistors. Each tested individually before joining all three.

Fanboy1337 @ 05/04/2009 - 17h22 a dit:

are the batteries in row (2.4 V total)? or parallel (1.2 V total)?



This is interesting. It is the first time I hear about it. I am not sure. They are in a container I bought like this one:

Posted Image

Fanboy1337 @ 05/04/2009 - 17h22 a dit:

i am no expert myself but maybe i can help



Thanks!
Edited by stubborn on 05/04/2009 at 19h04.
Fanboy1337 #4 05/04/2009 - 17h58

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hm, it looks as if the batteries are connected linear, so total voaltage should be 2.4

from ur datasheet I read that the forward voltage is 1.4V and the forward current up to 150mA

I entered 2.4V power supply, 1.4 V = U and 100 mA = I and the wizard came up with a parallel circuit with 3x 10 Ohms resistor. so you did everthing correct, actually.

ur circuit looks like this? top is + and bottom is -, afaik.

Posted Image
Edited by Fanboy1337 on 05/04/2009 at 17h59.
Kind regards from Germany.
Setting up my Freetrack for www.jumpgateevolution.com
stubborn #5 05/04/2009 - 18h52

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The circuit is built as per your diagram. See below.

Posted Image

I do not own an amperimeter (or whatever tool is used) so I cannot guarantee the leds correspond to the datasheet found online. They are pretty cheap so I don't mind frying few more if you come up with any idea :)
Edited by stubborn on 05/04/2009 at 18h54.
Fanboy1337 #6 05/04/2009 - 20h23

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did u connect both the red and black wire to the switch?

the positive lead should be the red one, afaik, and u connect it to the switch (SW), continuing the redwire from there on, like in this diagram:

Posted Image

otherwise you create a short-circuit, which might be the cause of your problem

and does every LED have its own 10 Ohm resistor? in the picture it looks as if u used only one. but i can't tell, as the rest is covered in tape :)
Edited by Fanboy1337 on 05/04/2009 at 20h29.
Kind regards from Germany.
Setting up my Freetrack for www.jumpgateevolution.com
stubborn #7 05/04/2009 - 21h06

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The remaining led is working no more. RIP.

Fanboy1337 @ 05/04/2009 - 20h23 a dit:

did u connect both the red and black wire to the switch?

the positive lead should be the red one, afaik, and u connect it to the switch (SW), continuing the redwire from there on, like in this diagram:

Posted Image

otherwise you create a short-circuit, which might be the cause of your problem



This is how I connected the wires to the switch. I followed instructions from somewhere online and it seemed to work ok, but I might have it misread:

Posted Image


Fanboy1337 @ 05/04/2009 - 20h23 a dit:

and does every LED have its own 10 Ohm resistor? in the picture it looks as if u used only one. but i can't tell, as the rest is covered in tape :)



Yes. Each led has its own resistor.

This may sound foolish to most but, is there any difference in functionality between these two wires?:

Posted Image

If we cannot get to anything, I will buy tomorrow 30 ohmn resistors and test from there as it seems the leds were getting too hot or, should I buy 10 ohmn 1/2w instead of 1/4w? It is so confusing for noobs...
Edited by stubborn on 05/04/2009 at 21h10.
Fanboy1337 #8 05/04/2009 - 21h45

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i can't help u with the wires, but the switch should not have the black wire attached to it, afaik.

only the positive cable is to be connected with the switch (check colors from ur battery clip, which lead is the positive one, maybe I am mistaken and black is positive, dunno actually :()

the switch works in that it interrupts the flow of the current equivalent to a simple cut through one of the wires. by actually swichting the switch ^^ u close that "cut" (that's why it is displayed as such in the circuit diagram)

if u r not sure about the switch (i wonder y it has three contacts) simply leave it out as u already have a plug in your setup
Edited by Fanboy1337 on 05/04/2009 at 22h16.
Kind regards from Germany.
Setting up my Freetrack for www.jumpgateevolution.com
stubborn #9 06/04/2009 - 01h26

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According to the following image, the power source (red positive wire) should go to the middle pin. This way I could redirect the current to either left or right using the switch. That is why it has 3 pins.

Posted Image

You are right: the black wires don't go to the switch, but in this scenario it is harmless. I will rearrange the cables but it won't make any difference.
Fanboy1337 #10 06/04/2009 - 12h58

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hm. well, the switch in the picture of your 3-point cap looks less than a toggle and rather like a real switch ^^ usually toggles have I O I depicted on them.

maybe it has three contacts to allow 2 parallel circuits being activated at once?
Edited by Fanboy1337 on 06/04/2009 at 12h59.
Kind regards from Germany.
Setting up my Freetrack for www.jumpgateevolution.com
stubborn #11 06/04/2009 - 13h03

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I just tried with 22 Ohmn 1/4w resistors.

The single point setup went alright but as soon as I joined the other two, one
of the leds started pulsing and in 20 seconds 2 leds burnt and I remained with just one. :pinch:

Should I keep trying with higher resistors or there is a problem in the assembly?

What resistors should I use to be on the safe side?
Fanboy1337 #12 06/04/2009 - 14h01

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take out that switch ^^ the rest looks just fine

22 ohms in this parallel setup is ok as long as u do not use more than 2 rechargable AA

the higher the resistor the lower the light intensity the less chance of frying ur LEDs

have u checked that "-" is connected to ur LED's cathode? in the datasheet it says the cathode has a blue mark on it
Edited by Fanboy1337 on 06/04/2009 at 14h06.
Kind regards from Germany.
Setting up my Freetrack for www.jumpgateevolution.com

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