> Easy build setup with SFH485P, Anyone can build this ! (for 5v Usb serial build see Page 2)
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gpbarth |
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Registered on : 24/12/2012
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Falcon @ 14/11/2009 - 10h59 a dit: 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).
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:
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.
I'm getting ready to build a 4-LED mount, and since it will be a series circuit like yours, and series circuits always have a constant current, 4 LEDs @ 50 ohms apiece would equal 200 ohms. Across a 6 VDC source, that would be approx. 33 ma. According to Mouser (where I bought the LEDs, the forward current in the SFH 485P is 100 ma, so there should be no need for a load resistor in the schematic - the LEDs will be operating at about 35%, or about 1.65 VDC drop across each LED. Does this sound about right? It might be better to use a 9 VDC battery.
-= Gary =-
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Steph |
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Hi Gary,
the 4-LED mount is outdated and do not have more functions than the 3-point cap or clip.
So go for this build.
100mA is the max. current for the SFH485P. You do not need to drive them at 100mA, as they works fine at 70mA and even 50mA. Choose the appropriate resistors for.
... 4 LEDs @ 50 ohms apiece would equal 200 ohms.
LEDs are non-ohmic and have diode like non-linear I/V characteristics.
Edited by Steph on 26/12/2012 at 11h59. |
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gpbarth |
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Steph @ 26/12/2012 - 05h56 a dit: Hi Gary,
the 4-LED mount is outdated and do not have more functions than the 3-point cap or clip.
So go for this build.
100mA is the max. current for the SFH485P. You do not need to drive them at 100mA, as they works fine at 70mA and even 50mA. Choose the appropriate resistors for.
... 4 LEDs @ 50 ohms apiece would equal 200 ohms.
LEDs are non-ohmic and have diode like non-linear I/V characteristics.
Thanks, Steph. I'm going for the 3-point cap setup and a series circuit, and have the LEDs, 6VDC switched battery case, 33 ohm resistors, and a cap. If the LEDs are 50 ohms and the resistor is 33 ohms, then the total resistance of the (series) circuit is 183 ohms. At 6VDC, the total current in the circuit would be 32 ma. And 32 ma x 50 ohms = 1.6 VDC drop across each LED. I could probably increase the size of the resistor to bring that down to the nominal 1.5V forward voltage of ther LEDs. I'm only having one problem now.
Looking at the dimensions of the cap model, it says 40mm from center for the lower LEDs, which equals 1.5 inches. That would result in a 3" total separation for the LEDs. Yet I look at the gallery and most of these pictures show more like 4" to 5" spread. How critical are the measurements? Or can I enter my own specific measurements when I program the software?
And I have a camera that isn't listed on the compatibility list. I have a Microsoft Life Cam HD-5000. I haven't tried opening it up, but made a filter from a floppy disc. I guess I'll have to hook everything up and see what happens. I'll post my results when that happens.
-= Gary =-
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Steph |
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Three LEDs mount: SFH485P, 6V
Led : 1,5V - 70 mA
Alimentation 6V
R = ( 6 – 3 * 1,5 ) / 0,07 = 21,4 ohms
P = 21,4 * 0,07 * 0,07 = 0,105 W
Get a 18 and 22Ohm resistor in 1/4W and try it. You will measure between 50 and 60mA. This is ok for the SFH485P.
Or can I enter my own specific measurements when I program the software?
Yes, you can. The only restriction is, that very small mounts are less accurate in tracking. |
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jurrasstoil |
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Registered on : 26/03/2013
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Hey,
quick question:
Can I use Falcon's plan and replace the 4x 1.5V normal batteries with 2x 1.2V rechargable batteries and just use a different resistor? And if so, which resistor should I use?
Thanks in advance
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Stormrider |
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Hi jurrasstoil,
I don't think it will work.
Just to use Steph's example:
Led : 1,5V - 70 mA
Alimentation 2,4V (instead of 6V)
R = ( 2,4 – 3 * 1,5 ) / 0,07 = -3 ohms??-3 ohm resistor don't exist.You have to little voltage to run 3 leds in serie
If you want to use your two batteries, you have to put your leds paralel instead of in serie.From my own experiance I known it doesn't take long before
the batteries run empty.
If you want to use 4x1,2V (rechargeable batterries)
you get something like this:
Led : 1,5V - 70 mA
Alimentation 4,8V
R = ( 4,8 – 3 * 1,5 ) / 0,07 = 4,3 ohms
P = 4,3 * 0,07 * 0,07 = 0,088Watt
Greetz Stormrider
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caranion |
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Class : Apprenti
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Registered on : 02/05/2013
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Hello friends.
I will build parallel version. I choose this resistor for SFH485P
http://tr.farnell.com/multicomp/mf12-15r/resistor-0-125w-1-15r/dp/9342656
Is it OK?
Thank you. |
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Stormrider |
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Hi caranion,
I can't give you an answer because I don't know what kind of powersource you want to use.
I think it is also better not to reply to someones topic with your own question.It is better and more polite to start your own topic.
maybe this topic will answer your question
http://forum.free-track.net/index.php?showtopic=3564
greetz Stormrider |
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caranion |
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Class : Apprenti
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I will build benmeijer's parallel build. It's 2*1.5 V. I thought it's better reply here. Sorry if I made mistake. I'm new.
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Stormrider |
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Hi caranion,
if yo use the formula:
(powerssource voltage - forward voltage led)/ resistor= current
(3v-1,5v)/15 ohm= 100mA.
Every led (paralel) will have a current of 0,33mA running throug.
I think, at least you must have a current flow of 60mA throug each led.
(3v-1,5v)/180mA= 8,333ohm
power dispensation is 60mA x 60mA x 8,3333ohm=29mWatt
I think that that is better value for your setup.
Or use a 25ohm resistor for each led (every led will get 60mA)
power dispensation= 90mWatt
I hope you understand my explanation, if you have other question, just ask.
greetz Stormrider
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dewey1 |
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caranion |
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Thanks Stormrider.
But it's hard both English and Electronics at the same time.
I decide to buy this:
http://tr.farnell.com/multicomp/mf12-30r/resistor-0-125w-1-30r/dp/9343024
(3 - 1.5) V / 30 Ohm = 50 mA
125 mW / 30 Ohm = I * I => I=64.5 mA
I couldn't understand what is the reference point in these calculations. But it's OK I think. |
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benmeijer |
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Updated startpost with this picture:
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mimod |
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Class : Apprenti
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Registered on : 22/03/2014
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Hi (benmeijer)
Although I have no f**king idea on electronics neither solder, Im decided to get a 3 IR Led USB powered clip. (PS: I'm missing a store section on the page)
I want the clip to be connected to the motherboard/case front panel USB, and according to your schemas a PTC fuse 250mA will be enough, but I want to be 200% sure.
If adding a higher fuse, higher resistance, LED, a special cable...double-safe my motherboard, just let me know.
How much it will cost if I do it myself? (Some people offer their models around 30€+shipping, and seems too much, isnt it?).
I'll appreciate if you could link farnell products to buy.
One final question:
Usually the clips are vertically aligned (front view) and at different distances (side view).
FRONT
O
O
O
SIDE
O
O
O
Will it be better or worse (or neither of them) to have the leds as a tripod (with different legs lengths)
FRONT
O
O
O
SIDE
O
O
O
Thanks a lot for your time and help.
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Steph |
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Hi mimod,
if you're not really sure about electronics do not connect your mount to the PC- USB port. You can blast your motherboard off.
Just use a normal USB-charger. You do not even need a fuse with a charger.
30€ is overpriced. LEDs and resistors cost about 5€ max., for the rest you can recycle a USB-mouse cable a 5V phone charger and so on.
Stay for the default measurements off the mount (aligned).
Edited by Steph on 23/03/2014 at 18h29. |
