> Easy build setup with SFH485P, Anyone can build this ! (for 5v Usb serial build see Page 2)
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Chunk3ym4n |
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When the positive wire and the negative wire branch off to three wires, do I just solder 3 wires to the battery wire?
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benmeijer |
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That's correct !
Practically you could connect the 3 leads (from the right in this scheme) from the resistors together, the other sides (left) should be isolated.
edit:
I found a picture in "Your point model constructions" to illustrate what I mean.
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Chunk3ym4n |
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So can I just connect the resistors to the leg of the LED if I wanted to? Also would it be a good idea to just solder the LEDs and then wrap the wires with electrical tape for the support?
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benmeijer |
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Yes you can connect one lead of the resistors to the (short) leg of the LED if you want!
Chunk3ym4n @ 27/12/2009 - 04h59 a dit: ...... wrap the wires with electrical tape for the support?
what support? |
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Chunk3ym4n |
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benmeijer @ 27/12/2009 - 13h22 a dit: Yes you can connect one lead of the resistors to the (short) leg of the LED if you want!
Chunk3ym4n @ 27/12/2009 - 04h59 a dit: ...... wrap the wires with electrical tape for the support?
what support?
Well I have hook-up wire that's pretty stiff and holds it's shape when you bend it and I think if I just wired it up and wrapped it with electrical tape it would hold.
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VoodooWoo |
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benmeijer @ 13/11/2009 - 23h02 a dit:
fullsize pics here:
http://forum.free-track.net/index.php?showtopic=466&page=8#12613
Hi @ All!
To those who want to use ben´s contruction:
I found this round item here in germany in a DIY-Store.
It´s called "Pflanzring /plant ring". There are 3 pieces of it in one package for 4,50€ 
Now I will start to build my second tracking device. My first one was build of some wires and was not that nice.
VoodooWoo 
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catar |
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I wonder what happens if you change polarity by accident? Does it blow LED's?
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Falcon |
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Well, it depends. If you shortly apply low voltage, just to get bit over froward current, you wont destry it, it just won't shine. But if you get over reverse current (perhaps 5V if I recall), you will destry the LED.
As some have opposite polarity to others (short vs long "leg"), I bought 4 then tested the first it carefully. I didnt damage the LED. If you get the Osram SFH485 schematics here are right (+ on short legs) which is opposite to many other.
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SomeBum |
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I tried to construct a three point clip using SFH485P LEDs wired in a series connection. I'm worried that I may have fried my LEDs, but I hope not. I'm using two AA batteries to deliver 3V which goes through a 33-Ohm resistor, delivering oh about 90.9mA to the LEDs if I recall my calculations correctly. I removed the IR filter on my VX-1000 webcam, but it does not detect the LEDs. I am going to troubleshoot the system with a multimeter later, but I'm in my initial panic phase and quite worried! I only bought one extra LED but if the three that I'm using are burned out then I'm out of luck. Any tips?
EDIT: I just wanted to clarify that yes, I made sure to observe the polarity of the LEDs. All of my negative connections come from the leg with the flat edge on the plastic.
Edited by SomeBum on 08/01/2010 at 04h38. |
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benmeijer |
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I think you mixed up two ways to build the 3 point clip/hat. You talk about "in a series connection" and "a 33-ohm resistor (one ?) and 3 Volt.
Are you sure you wired your build in a "series connection" ?
See the two pictures below
1. Parallel build
- 3 volt
- 3 x 30 ohm resistors
2. Serial build
- 5 volt
- 1 x 10 ohm resistor
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SomeBum |
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Absolutely certain it was in series. I had it wired like in the circuit diagram Resistor-Diode-Diode-Diode and applied 3V (measured as an effective 2.6V with multimeter) across the resistor (measured as 32.6 Ohms) which should give me a current that would work well across the LEDs (<100mA). I did it in much the same way as your picture for series, but instead of 10 Ohms I used the 33 Ohm resistor and connected to x2 AA batteries instead of USB for which I assume the fuse is needed.
Does it matter if my resistors are marked as 1/2 watt?
Provided that I didn't destroy my LEDs, I am probably going to reattempt the design in a parallel build.
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benmeijer |
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Well you definitely mixed the builds ..... 
In serial setup you must have a minimum of 4.5 volt to light the leds (3 x 1.5 V forward), thats why 5 volt USB is perfect for this build.
I think you can use your build ... if you use 2 extra batteries ( 4x 1.5 = 6 V)
lets put these values in the led wizard:
6 Volt
Battery power
1.5 V forward
45 mA ( guessed)
result 33 ohm ...... should be bright enough to use !!
give it a try or re-build it with the values in one of the shemes above.
edit: 1/2 watt resistor is ok! |
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SomeBum |
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All I have is a holder for two batteries and more than enough resistors so I'll just do the parallel configuration. Didn't know that about the forward voltages.
Thank you for your help!
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Freaky |
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Hi Guys,
In the Series set up what Is the values of the PTC Fuse?
Thanks in advance this thread has been very helpful so far.
Freaks
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benmeijer |
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A PTC fuse is a resistor with almost no resistance while current < I(hold). When your assembly uses more current the value of the resistance gets higher, and when the current becomes > I-(trip) (short-circuiting ?), it gets very high, and so protecting your power source ( USB / motherboard).
So you can use a PTC fuse with 200ma (I-hold) and max 300ma (I-trip).
read more here: click |
