> Easy build setup with SFH485P, Anyone can build this ! (for 5v Usb serial build see Page 2)
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Brilhasti |
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Class : Apprenti
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Registered on : 04/02/2011
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Hi all
I'm completely ignorant of electronics I'm afraid.
Can anyone confirm if these are the correct components?
LED: http://www.maplin.co.uk/3mm-infrared-emitting-diode-48038
Resistor: http://www.maplin.co.uk/10-ohm-to-30-ohmmetal-film-0.6w-resistors-341331 |
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benmeijer |
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Class : Habitué
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Registered on : 19/07/2008
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A 3 mm led is to small, use 5 mm. And probably the angle of the lens is to narrow.
Why don't you order the SFH485p ?
look here for a shopping list (for serial build on page 2)
if you prefer the parallel build (on page 1) you might need other values for resistors.
Here a list and link to Farnell (UK) of resistor values:
6.8 ohm
10 ohm
13 ohm
18 ohm
22 ohm
27 ohm
30 ohm
33 ohm
39 ohm |
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sydney |
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Class : Apprenti
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Registered on : 19/04/2011
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Hello everyone...
I need to say, at first, that I am totally ignorant in electricity&co, so it this will be my first attempt with "building something electric" 
I would like to use the usb-scheme on page 2 for my setup, and I ordered at Farnell the items in the related shopping list...now, one question is about soldering...I have no soldering irons and I am looking for a practical mean to substitute it with something else in order to join the wires and the resistors/leds...I thought about using the isolating tape and then put everything into a heatshrink tube...will it be isolated then or are there any risks of damage? In addition, should I buy some specific wire, with particular carachteristics (I have read 5v if not wrong)?
Thanks and sorry for these embarassing questions
Syd |
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benmeijer |
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You better use a part of a small electric wire connector like this one:
remove the plastic to make it smaller and use tape or heatschrink tube to isolate it (and as answer to your question: yes heatshrink isolate your wires / use 2 pieces ...).
It is not impossible just to wrap wires around the lead of a led and isolate it, but I do not recommend it.
And an solering iron just cost 10 euro or so give it a try. If you don't know how to solder just google for Youtube instruction videos.
Good luck with your build. |
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a1adin |
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Registered on : 24/01/2010
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hi benmeijer,
about your 5v Usb serial build,
has anyone tried it?
since this is serial, how about the brightness of each LED?
is the 1st LED brighter than the 2nd LED?
and the 2nd LED brighter than the 3rd LED?
please verify.
thanks.
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benmeijer |
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See my own build 5v serial <Click here>:
Can you see difference in brightness?
Here with my diffuse making IR-balls (Fimo) over the leds, read the topic <Click here>
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a1adin |
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hi benmeijer,
you are right, those look the same.
and wow, you have a very good idea diffusing those LEDs.
I don't know if I can find FIMO in my city,
but I think I am going to try it!  |
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jannypan |
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No one seems to mention it anywhere and I think that's one of the most important thing. In this setup it's something like 14 hours? Buy Runescape Gold
Buy Runescape Gold
Runescape Gold |
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a1adin |
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hi benmeijer,
I want brighter LEDs for my new usb serial build freetrack (based on your picture),
but I can not find 6.8 Ohm resistor,
only 6.2 and 7.5 Ohm,
which one should I use?
how many mA can the LEDs take?
is 6.2 Ohm too bright?
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benmeijer |
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a1adin @ 17/05/2011 - 17h30 a dit: hi benmeijer,
how many mA can the LEDs take?
is 6.2 Ohm too bright?
The SFH485P can take 100 mA max. If you want it brihgt you can even use a value near 5 ohm. But 6.2 is bright enough!
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a1adin |
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I think I am going to try 6.2 ohm.
Thanks benmeijer! |
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richb |
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Hi
I've just been building a 3 point model and plugged it in to test to discover the field of view was pretty restricted, i.e. small rotation lost sight if IR LED's.
Actually it lost sight of 2 LEDs. Turns out the third one, that had masking tape over it while the glue dried could cope with massive amounts of rotation.
Moral of the storey. An alternative option to grinding the LED flat seems to be to cover it in masking tape. Bizzare, but works for me.
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Tr0n |
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Registered on : 19/09/2011
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Hi new here and I must say what a terrific project.
Anyway I built the SERIES tracker based on the SFH485P and must confess it works really well.
The one thought that has now gone through my head is that when using the USB power source it is preferable to make use of a PTC. Now from my calculations the PTC has an average ohm rating of around 3.5 (min 2.5 max 5.5). So in builds that take the 5v power from the USB then surely the PTC resistance should be taken into consideration.
RT=R1+R2 ...
RT=PTC @ say 3.5 + Resistor @ 6.8 ...
RT = 10.3 ohms ...
So now if we introduce Ohms Law
I=V/R ...
I= 5v / 10.3ohms = 48.5mA
So introducing the PTC in the series circuit shouldn't the 6.8Ohm resistor really be a 3.3Ohm resistor to get 75mA out of the LED's
Anyone any thoughts on this ?
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benmeijer |
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Tr0n,
Thanks for your input!
You're right, the PTC has some initial resistance. Could be 3 - 5 ohms.
In post nr. 118 I mentioned it (last line).
I will update the serial build posts with your information.
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Tr0n |
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Registered on : 19/09/2011
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5v Series - PTC Resistance - For those interested and remembered their I=V/R
TE CONNECTIVITY / RAYCHEM - RXEF010 - POLYSWITCH, RADIAL, 0.1A
[100mA Hold / 200mA Trip]
http://uk.farnell.com/jsp/search/productdetail.jsp?sku=1212738
Tech Data Sheet
Initial Resistance Min: 2.50 ohm
Initial Resistance Max: 5.40 ohm
Typical Resistance: 3.50 ohm
Also just for info
7.5 ohm = Maximum resistance of device when measured one hour post trip |