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RSS >  Easy build setup with SFH485P, Anyone can build this !   (for 5v Usb serial build see Page 2)
benmeijer #16 23/07/2009 - 20h47

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saied @ 23/07/2009 - 12h13 a dit:

i dont know where to buy the leds and resistors from. if u could pherhaps tell us where u bought them from. i live in the usa



I bought my leds from a local electronics-parts store, they do not deliver in the USA, but try to google "SFH485P"and "youre state" to find a store where you can buy them.

I've found this:

leds:
http://www.newark.com/osram/sfh485p/_/dp/01M8813

batteryholder (no switch ...use exernal):
http://www.newark.com/bud-industries/hh-3632/battery-holder/dp/34M2186

resistors:
http://www.newark.com/multicomp/mcmf0w4ff300ja50/metal-film-resistor/dp/58K3839

"ma" means "milli-ampere"
Edited by benmeijer on 23/07/2009 at 20h49.
saied #17 24/07/2009 - 16h35

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this is a very good topic. thank you again.
WilderPilz #18 03/08/2009 - 10h53

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Hi benmeijer

I dont want to Hijack your Thread but just to have a better impression how your idea can look like, I build this little sweat thing.

The final connection to the Battery is missing.
I did this in just 2,5h including collecting all the stuff in my place.
The Cap I use, my first build, took me round about 1 day to build.

Pros
- Very easy to build
- Very light without Batteries
- Easy switching LED´s

Cons
- Power source
- Batteries put heavy weight to one side of your head (put some Batteries to the other side of your Head to balance  :D )

But for Beginners this is pretty perfect, because you can tweak your Setup very easy.
If you think about an alternative Power Source you can use a Power Supply or use a USB Cable (NOT FOR BEGINNERS!!!!!)
But remember, if you switch your Power Source you have to use other Resistors!!!!!!

And some Pictures
Posted Image

Posted Image

Posted Image

I hope this Pictures will make this Thread sticky  ;)

Very well Done!
Edited by WilderPilz on 03/08/2009 at 11h07.
benmeijer #19 03/08/2009 - 22h18

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I started this topic because some people don't understand diagrams like these:
Posted Image

and there's a issue with the long leg of the SFH485P is negative.

I wanted to show how simple it can be.

Oh ... and when you put your batteries on top of your head there's almost no problem with the weight / or balance!
See my build: http://forum.free-track.net/index.php?showtopic=466&page=4#8487.


Soon I will made "a easy build setup using 5v power from the computer ...." !
schermvlieger #20 19/08/2009 - 07h05

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Great post benmeijer!

I don't now the least bit about electronics but with these instructions I think I might be able to pull it off :)

I have one question though: can this design be modified to use a single resistor in the battery box, before the wire is split off in 3 branches? If so what components would be required?

Many thanks,
Schermvlieger
benmeijer #21 19/08/2009 - 21h56

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schermvlieger @ 19/08/2009 - 09h05 a dit:


I have one question though: can this design be modified to use a single resistor in the battery box, before the wire is split off in 3 branches?



simple answer: I don't know. The led calculator give a result how to build this with 3 leds. I think there is a reason for it but I can't explain why.

Maybe someone else can explain this.

I've found a good led calculator (choose as output "wiring diagram"): http://led.linear1.org/led.wiz

But resistors are very cheap and they are very small, so use 3 and  hide them on top of the batteryholder.
rus_cb #22 20/08/2009 - 06h04

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I'm not 100% sure (since i'm a complete novice) but I think it's something to do with the power of the battery.  If you are using a low voltage set up (eg. 1.5V or 3V) you'll need to run a parallel circuit because the voltage is only running through one resistor and one LED (per channel if you like).  If you want a serial circuit then you'll need a higher voltage (eg. 9V) to get through one resistor then 3 LEDs.
schermvlieger #23 20/08/2009 - 07h29

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Thanks guys!

I'll pay a visit to the local electronics shop with the parts list from this post :)

/edit

Jay it works great! Thanks again benmeijer!
Edited by schermvlieger on 21/08/2009 at 07h55.
benmeijer #24 13/11/2009 - 22h02

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New scheme for serial build using 5V USB power:

Posted Image
new uploaded picture, tinypic had removed original 7 feb 2011

edit 1: (If you use other type of leds, (not SFH485P) the shorter leg is almost  negative ! check your datasheet)
edit 2: aug. 2010 Updated picture with more specific info (old picture here: http://i36.tinypic.com/25zsge8.jpg)

If you use a PTC, take in consideration that this component has some initial resistance (3- 5 ohm). If you want 50 mA - subtract this inititial value from the 10 ohm (my advice: use the 6.8 ohm!).

for a example, see my latest construction:

Posted Image

fullsize pics here (post #105):
http://forum.free-track.net/index.php?showtopic=466&message=12613
Edited by benmeijer on 21/03/2012 at 11h48.
Falcon #25 14/11/2009 - 15h59

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Hi, yesterday I tought about your first setup and wondered about pros and cons of serial vs paralel and came with such serial circuit modification:

Pros:
+ 1/3 of current in circuit then in paralel setup -> 3 time more battery life (actualy 1,5 times per battery since it uses 4 batteries)
+ Easier soldering - only 1wire on 1 wire vs 3 wires on 1 in paralel, saves space and resistors (though they are cheap).

Cons:
-1.2V too low so only nonrechargable batteries


*At 30mA with 2400mAh batteries, it should work 80 hours! (48h on 50mA).
*Can be used  with 6V AC/DC stabilised source, if batteries are not prefered.
*In upgraded version, it is possible to adjust brightness by switching resistors (trough connectors).

Posted Image

This is my first plan for LED tracking device and I have not much experince in electronics, but I hope have it right.

BTW as I checked resistor values according to Ohm law, LEDs seem to be counted as 50 Ohm resistance added (-> Serial: 6V/(50R+3*50R)=0.030A or Parallel: 2.4V/(30R+50R)=0.030A), am I right?

I have cam that is easy to IR mod + floppy VIS filter. According to HW FAQ, 30mA should be OK. Whats your experince with brightness setups (day/night), since I see only 40+mA's here?

I was also thinking on clip/cap construction since i prefer to have something that would be as light as possible (batteries would be on table) and possibly independent on audio headset. Then I saw thick rubber-coated wire and got idea:

Posted Image

If it looks confusing, look at this headset and you 'll get the idea:
http://info.vltavastores.cz/ceniky/imagesSE/normal/205807.jpg

Good thing is that it is easy to wrap it around head for maximum ergonomy and its incredibly light.

I plan to create the velcro plate from modelling plastic, then harden it by boiling. I plan to make the track clip similar way using the wire and modelling plastic. It would connect by velcro -> could be attached to various other headsets.

EDIT: I successfuly created it, now posted in Your point model constructions thread.
Edited by Falcon on 29/12/2009 at 20h44.
benmeijer #26 14/11/2009 - 18h32

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I think if you're using 3 leds, 30 mA each, you consume 90 mA. And the resistor also consumes current.  I'm not an electrician so maybe I'm wrong.

I like your idea of a variable resistor, but maybe you can use a potentiometer (http://en.wikipedia.org/wiki/Potentiometer) ? 22 ohm + var 0-30 ohm.

I have no problems with brightness (at day / night) because I'm using a Wiimote .... that is a IR cam. I power my leds  50 - 75 mA. Maybe it will work with 30 mA .... Try it, and let us know.

I also had thoughts to make my setup with thick rubber-coated wire, but could not find the perfect material. What will you use?

I made my plates from (plastic):

Posted Image  Posted Image
Edited by benmeijer on 05/03/2014 at 14h09.
Falcon #27 14/11/2009 - 19h54

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I looked at potentiometers at online store, but seen just values like 100 Ohm and more (don't even know which was max (perhaps 100) and which min (0?)).

I just found the wire at home, its 2-2,5mm copper wire in rubber insulatrion. The electritians one. Just look into some Electro store, perhaps you find some. It just need to be thick one and homogenous (not made from thin fibres) to retain shape.

Power consumption: You can imagine the current as flow of electrons, just like water. Resistor don't consume current (aside from the power dissipation - heating). It's just obstacle  like narrowing in water pipe - less volume of water can flow per second at given pressure gradient (less electrons at given voltage). The LEDs doesn't eat much power either, it is rather that the electrons flow from one pole to another (the voltage is difference in potentials - eg. potential gradient). Once the gradient diminishes, the  battery is emty.

Now in parallel, each branch need 30mA and in the main brach (before splitting) is 90mA. There is one resistor and one LED both an obstacle for current in each. Different electrons run trough each LED.

In serial, you hace only 30mA since there is only 1 branch and the same electrons go trough all the LEDs (imagine 3 water mills at one creek). But this means that there are more obstacles (resistor + 3LEDs) for the current, so it needs more voltage (potential gradient) to push trough.

I think (not sure) that the 1.5V means that each LED needs 1.5V potential gradient between anode and cathode for electrons to push trough. Resistor also builds potential gradient, depending on resistivity and current. That would be similar to pressure building at the begining of narrowing in pipe. Then it makes sense to use high voltage for serial circuits.
Edited by Falcon on 14/11/2009 at 19h59.
eLeTrO #28 18/11/2009 - 22h14

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benmeijer @ 13/11/2009 - 23h02 a dit:

New scheme for serial build using 5V USB power:

Posted Image



for a example, see my latest construction:

Posted Image

fullsize pics here:
http://forum.free-track.net/index.php?showtopic=466&page=8#12613



Hi benmeijer!!
Please, let me know why your scheme is different of the wizard??
Calculating by LED Assembly Wizard setup they show:
Power supply- 5v
Forward current- 75mA
Forward voltage- 1,5
RESISTOR = 27Ohms

Why you get 10 Ohms?!?!?

thanx!
benmeijer #29 18/11/2009 - 23h03

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Select USB-Power in the wizard!
razor1911 #30 18/11/2009 - 23h33

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thanks for the info benmeijer
I tried your serial design with 10ohm and worked great.

however is your dimentions for camera sitting above or under the screen?

regards

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