> Easy build setup with SFH485P, Anyone can build this ! (for 5v Usb serial build see Page 2)
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benmeijer |
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I think you must remove the IR filter from the eyetoy. But it is strange you see the IR led of your remote control.
Use your digital (photo)camera or phone to check if the leds in your build are visisble.
check that you're using the right resistor in your build (i.e. 10 ohm in stead of 10 kOhm)
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tracker |
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expensne @ 01/12/2010 - 17h34 a dit: is it right that you nearly cant see the SFH485P light? or did I do a mistake in building the free track?
You should see a small red dot in leds with your own eyes. In camera or mobile you should see light.
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hillbilly |
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Hey guys, just wondering what efect the Watt rating of the resistors has in this build? Will a resistor with a 1/2 Watt rating perform the same as one with a 1/4 Watt rating. Am i right in understanding that the Watt rating is related to the amount of power the resistor can take before it fails?
Thanks.
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dewey1 |
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hillbilly @ 13/12/2010 - 09h44 a dit: Am i right in understanding that the Watt rating is related to the amount of power the resistor can take before it fails?
That is correct. Twice the power between in a 1/2 watt.
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RedLine |
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Hi @ all..
I'm going to change my led's (the first construction wasn't so good because of the very narrow angle of view of my current led's) and i ordered sfh458p..
In the specification of the led there is written:
1,5v @ 100mA
3v @ 1A
I'm trying to find out wich voltage should i give them if i want a forward current of about 300mA
Maybe 2v?
I will use external usb power from a phone charger (5v 1A max) since the usb plug on the pc will only give max 100mA...
Have 3 led's so 300mA per led sounds reasonably to me (900mA total)
Want to have them as bright as possible..
Came out i have to buy 10Ohm 2W resistor (metal film so 1% tollerance) assuming 2v forward voltage and 300mA forward current.. Could the relation Fv to Fc be correct??
Thanks a lot for the help!!
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dewey1 |
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RedLine @ 14/12/2010 - 18h02 a dit: Hi @ all..
I'm going to change my led's (the first construction wasn't so good because of the very narrow angle of view of my current led's) and i ordered sfh458p..
In the specification of the led there is written:
1,5v @ 100mA This is maximum continous current! Use 75mA instead! Never operate at the maximum!
3v @ 1A This is for pulsed mode operation only. Do not use this unless you know how to design/build proper circuit!
I'm trying to find out wich voltage should i give them if i want a forward current of about 300mA
Maybe 2v?
I will use external usb power from a phone charger (5v 1A max) since the usb plug on the pc will only give max 100mA...
Have 3 led's so 300mA per led sounds reasonably to me (900mA total)
Want to have them as bright as possible..
Came out i have to buy 10Ohm 2W resistor (metal film so 1% tollerance) assuming 2v forward voltage and 300mA forward current.. Could the relation Fv to Fc be correct??
Thanks a lot for the help!!
Please read the reply in red above.
You could use a constant current source like this:
http://forum.free-track.net/index.php?showtopic=2666
But set it for 75mA constant current.
Use 3 of the SFH485P in series with a current of 75mA. Remember the KISS principle! Keep it simple stupid.
Do not overcomplicate what your trying to do.
Had you used the SFH485P's in the first place, you probably would not be attempting your latest proposal.
Edited by dewey1 on 14/12/2010 at 19h46. |
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hillbilly |
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I am planning a build using an old mobile phone charger as the power sourse to a three point cap model and intend to run the circuit in series as described earlier in this post. I am however finding it difficult to figure out which resistors to use as the LED Assembly Wizard is difficult to understand for the noob.
The power source has a DC output of 5.7v, rated at 800mA.
I am also using the recommended SFH485P LEDS - which i would like to output 50mA or 75mA (Whichever would be more appropriate)
Could someone please advise on the resistors that would be required in this build.
Thanks in advance.
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dewey1 |
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hillbilly @ 14/12/2010 - 20h46 a dit: The power source has a DC output of 5.7v, rated at 800mA.
I am also using the recommended SFH485P LEDS - which i would like to output 50mA or 75mA (Whichever would be more appropriate)
Could someone please advise on the resistors that would be required in this build.
Vs-3Vf=Vdrop So 5.7v-(3x1.5)=1.2v
R=Vdrop/current in Amps
R=1.2/.05=24 ohm for 50mA
R=1.2/.06=20 ohm for 60mA
R=1.2/.08=15 ohm for 80mA
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RedLine |
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Please read the reply in red above.
You could use a constant current source like this:
http://forum.free-track.net/index.php?showtopic=2666
But set it for 75mA constant current.
Use 3 of the SFH485P in series with a current of 75mA. Remember the KISS principle! Keep it simple stupid.
Do not overcomplicate what your trying to do.
Had you used the SFH485P's in the first place, you probably would not be attempting your latest proposal.
hi i didn't knew that 3v @ 1A is meant for other applications .. than i will re-build same setup as now (usb power and 3 LED in parallel .. using 30Ohm resistors)
i DO KNOW that with the SFH485P it would be the best setup but in my local store they had only lower spec ir LED's and since i wanted to give them a try i bought them .. obviously buying 3€ worth of LED and spend 10€ for shipping isn't so nice so i just tryed out the 0,10 LED of the shop first 
i event tryed to adapt them by cutting the lens of but wid poor result so now i ordered the SFH485P ..
Edited by RedLine on 15/12/2010 at 16h51. |
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dewey1 |
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@Redline;
If using +5v power via PC USB, you have a current limit of 100mA on USB 2.0 port.
If parallel LEDs then max of 33 mA each for 3.
Wire in series for 75mA is much safer on a USB port.
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blueman |
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Hey guys, can u help me on this?
I want to build a 5v usb serial like benmeijer, but I dont know if ipod usb power adapter (5v, 1000mA) is regulated.
If not, can i use the 5v cable from my PSU ? (not usb)
PS: Many thanks to freetrack programmers and you guys  |
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benmeijer |
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I think that your Ipod usb power is regulated, so use it.
And of course the PSU of your PC have perfect 5V. see picture ....
An other alternative is to use 5V from a keyboard PS2 plug (use pin 3 and 4) if you use an USB keyboard.
read more : Power from your PC - http://www.epanorama.net/circuits/power_from_pc.html |
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blueman |
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 wow , that was a quick reply, i didn't expect that
Thank you benmeijer, but is there any method to test it (ipod usb power adapter) except voltmeter (if thats how its called) ?
Edit: if its not regulated my leds will die first, right?
Edited by blueman on 22/12/2010 at 15h33. |
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benmeijer |
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If your power adapter is not regulated it has not exact 5v , but maybe 6v.
If you use a 6.8 or 10 Ohm resistor your leds should stay alive !
But I think your USB power adaptor is regulated...
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jimbop2 |
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For anyone building the USB-powered model from post #112 in this topic in Australia you can get the components from Jaycar:
CAT. NO. ZD1945 = 5mm Infrared Transmitting LED
CAT. NO. RR1522 = 6R8OHM 1/4 WATT 5% CARBON FILM RESISTOR
This serial design works perfectly directly into the computer without the optional polyswitch PTC fuse.
I've had excellent results with the clip design mentioned in another post using stiff, plastic-coated coathanger wire as the frame: http://www.free-track.net/forum/index.php?showtopic=2302
You definitely need to remove the IR filter from your webcam! |