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FreeTrack Forum > FreeTrack : English Forum > Support : Tracking System > Is this SFH485P?

RSS > Is this SFH485P?, possible to use SFH485P without IR flitter?

silenthunter	#1 18/11/2007 - 05h03 Top
Class : Apprenti Posts : 7 Registered on : 02/11/2007 Off line	Is this SFH485P? Without IR flitter, I cannot use this LED at day because its beam is very small and I have to move threshold to left for catching beam, but other lights will be catched at the same time. Move threshold to right, FT cannot see the beam. Why the SFH485P's beam is small ? Mine is with a 100ohm resistance and was connected to USB. Are there any problems on my resistance, connection or I just need the flitter ?
tristan68	#2 19/11/2007 - 09h34 Top
Class : Electronicien en chef Posts : 651 Registered on : 10/07/2007 Off line	hello silenthunter. Is this SFH485P? Looks like it The SFH485P has a rather unusual case (flat top), so its very easy to visually identify it. Without IR filter, By IR filter , you mean the filter you put in front of the webcam lens, right ? This isn't an IR filter but a VL filter (visible light). It cuts visible light and lets IR go through. I cannot use this LED at day because its beam is very small and I have to move threshold to left for catching beam, but other lights will be catched at the same time. Move threshold to right, FT cannot see the beam. Why the SFH485P's beam is small ? Mine is with a 100ohm resistance and was connected to USB. Are there any problems on my resistance, connection or I just need the flitter ? The reason the SFH485P is often used for FT is it has a strong and wide beam. But to get this strong beam, you need to power them accordingly. I assume you use a single led or parallel led setup in your example. Doing so, you let about 35mA in each led by using a 100ohms resistor. This current value should be more than enough to many webcam setups (It may even be too bright if your webcam was ir-modded by removing the webcam's builtin IR filter). But this is webcam dependant, since it relies on the webcam's builtin IR filter. Some webcams aren't IR sensitive , unless modded. If you have such a webcam, you'll need : - either to put more power in your SFH485, to get more brightness. - either to IR-mod your webcam You can increase the SFH485P current up to 70mA without any problem (thats using a 50ohms resistor for a single led setup powered by a 5v source). BTW : I don't recommend powering your led setup directly from USB, in case of a problem, you may fry your PC motherboard. Better use an old power supply, from a cell phone or a small electronic device. cya
silenthunter	#3 19/11/2007 - 14h12 Top
Class : Apprenti Posts : 7 Registered on : 02/11/2007 Off line	Thank you for your reply. Yes, I mean VL filtter. I made mistake. Does it mean it's possilbe to use SFH485P without VL filtter at day by changeing resistance to 50ohm ? If so, then I will have a try and let you know results.
tristan68	#4 19/11/2007 - 16h57 Top
Class : Electronicien en chef Posts : 651 Registered on : 10/07/2007 Off line	Hello Silenthunter the VL filter should always be used. It increases constrast between the IR beam sent by your leds and the various VL light sources or reflexions. Your problem is mainly a webcam's lack of sensitivity to IR radiation. The first step to try and solve is to increase your led current to 70mA, and see if this solves your problem. You should be able to use the sfh485 and your webcam with a vl filter , without any problems. question : what is your webcam model ? cya
silenthunter	#5 21/11/2007 - 09h11 Top
Class : Apprenti Posts : 7 Registered on : 02/11/2007 Off line	Thank you very much for your help. The webcam is not a famous brand. It uses vimicro301. FPS is very stable on 31. I even tried to use a 30ohm for SFH485P, but FT still got a beam which is smaller than 5mm red shining LED. I made a 1000ohms for that red shining LED, it's not so bright but it's enough. To buy VL flitter is not economical although I can buy one.
Kestrel	#6 21/11/2007 - 09h57 Top
Class : Webmaster (admin) Posts : 780 Registered on : 13/07/2007 Off line	silenthunter @ 21/11/2007 - 09h11 a dit: To buy VL flitter is not economical although I can buy one. A photographic quality VL filter is not required! Just use the magnetic disc inside old floppy disks or fully exposed developed photographic film negatives. Support FreeTrack
tristan68	#7 21/11/2007 - 17h40 Top
Class : Electronicien en chef Posts : 651 Registered on : 10/07/2007 Off line	silenthunter @ 21/11/2007 - 09h11 a dit: Thank you very much for your help. The webcam is not a famous brand. It uses vimicro301. FPS is very stable on 31. I even tried to use a 30ohm for SFH485P, but FT still got a beam which is smaller than 5mm red shining LED. I made a 1000ohms for that red shining LED, it's not so bright but it's enough. To buy VL flitter is not economical although I can buy one. Hello silenthunter since you tried your led with a 30ohms resistor, at 5v power supply voltage : if your webcam still doesn't perceive the leds correctly, then cause is your webcam has certainly a strong builtin IR filter. 3 available solutions : - use red leds. - IR mod your webcam (only if you think you're able to do it, and if your your webcam is only used for freetrack). - change webcam Sorry to have to say that , but according to the infos you gave , we only have those choices left. keep us informed if we missed something. cya

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