FreeTrack Forum
|
Off line |
Hello remoteplayer1
If you plan to use SFH485P , don't use them at 100mA, you would overpower them !!! Use : 50 to 75 mA, if you plan to use an unmodded webcam. 25 to 50 mA, if you plan to use an IR modded webcam. About the resistor power : Once you've found the correct value, you need to get a resistor sustaining AT LEAST the dissipated power. As a rule of thumb , you usually use at least a resistor able to widstabd 2x or 3x the calculated dissipated power. So for your 0.05 w of calculated dissipated power , I would use the plain standard 0.25w carbon resistor (cheapest resistor ever... period  )Don't forget to recalculate your resistor for the desired led driving current. cya |
|
Off line |
hello remoteplayer1
Well, lets do this step by step. 1) Please tell me if you plan to use an IR modded webcam or an unmodded (plain stock) webcam ? 2) USB power ... I usually don't recommend it , since you aren't proficient in electronics (risks of frying your PC's motherboard if you make a mistake)... Please confirm you want to use USB power , or tell me what power supply you intent to use (in case of a power adapter, a pic of the characteristics plate would be fine too )thx cya |
|
I will be using a vx-1000 lifecam by microsoft --- modified IR filter removed with floppy disc cut out on top of lens (can't find any negative film as of now)
this color coded resistor thing though, is whats confusing me, why can't someone just tell me exactly what resistor i need to use. Everyones giving me diffrent ways on wordings of resitence, voltage. Then tell me i need .25 watt, which i thought was the mutiplier. i am using LEDS: 1.5v OSRAM SFH 485 P < max 100 mA 5v USB 3 point head tracking now assuming i use 50mA i will need a 10 Ohms 5% quarter watt resistor? its saying disipated power 0.03 watts <--- do i need to know this for the color code ? 4 band: brown black black _space_ gold 10 ohms 5% 25 mA 20 ohms 5% same with 50 mA i would require this resistor at 1/4 watt 4 band: red black black black _space_ gold i will picking either 50mA or 25mA with following resitor(s) of choice, would these work? And should i use a PTC fuse for insurance (specifically what kind and how do i know), also how do i wire that in series before the resistor sorry for asking so many questions  |
|
|
Off line |
Hello Remoteplayer1
Do you know the meaning of the term : weekend ?  Sorry , just wasn't avail, happens....
No, the color code only provides the resistor value and precision, not it's max admissible power.
Well, you just gave them yourself : thats : 10 ohms 1/4w if you want to put 50mA in your leds 22 ohms 1/4w if you want to put about 25mA in your leds As I told you in my 1st message , the wizard gives you the power dissipated in your resistor (ie : 0.03w). You need to get a resistor sustaining AT LEAST that power, so EVERY resistor allowing more than this value is OK (you can use 1/4w, 1/2w, 1w, 2w, 10w, but this gets big.....) I told you to use 1/4w resistor because : - they sustain the power you'll have them dissipate. - they're the cheapest resistors you can find (no need to pay too much). BTW, you don't really need to know the color code , since you're going to buy the resistors. You'll ask for a model, and you'll get that model. The color code is mainly provided for people salvaging parts on old printed circuit boards, or if you buy a complete set of resistors....
Yes, its better to use one if you're powering your setup directly from an USB port. you just mount in serial with the setup so, you'll have : USB positive lead -- PTC -- RES -- LED1 -- LED2 -- LED3 -- USB negative lead cya |
|
Off line |
|
|
do you mean it can only request more if its connected with data and request it via the computer?
im wiring these in serial see my most previous post for the exact setup the others are asking for right setup. so for 25mA leds it would require 250 mA of total current 50 mA 500mA of total current throughout the usb adapter i would use would work for 25mA as its 4.2v --- 400mA rated but not 50mA
are you directing to this to me and other, it subtracts in series right so im still good, but i might need a usb hub to get 250- 500mA is what your saying also when i try to get a reading from a multi meter with the red and black wire on the usb plugged into computer or adapter i don't get any readings, whats up with that? its a usb extender cable, don't see how it wouldn't work. |
|
|
Off line |
Hello remoteplayer1.
If you want to stick with USB : to keep things simple, just remind you wont normally exceed the USB power capability ( we're building a freetrack clip, not a flashlight  )Since you'll use a serial setup , your setup current need usually won't be far greater than 50 mA (often less than this values , depends of your preferences while building and modding your webcam).  Now , if you want to go with batteries, your recommended setup will be different based of the battery type you'll use. If you use 4 standard (alcaline) batteries (6v pack) : recommended setup : serial  you can use the following resistor values : - 62 ohms 1/4w for 25 mA (usual value if your webcam is IR modded) - 30 ohms 1/4w for 50 mA (usual value if your webcam is NOT IR modded) - 20 ohms 1/4w for 75 mA (usual value if your webcam is NOT IR modded and have difficulties to see the leds) If you use 4 rechargeable (NiCad or NiMh) batteries (4.8v pack) : recommended setup : parallel  you can use the following resistor values (3 resistors needed in this setup, 1 for each led) : - 130 ohms 1/4w for 25 mA (usual value if your webcam is IR modded) - 66 ohms 1/4w for 50 mA (usual value if your webcam is NOT IR modded) - 47 ohms 1/2w for 75 mA (usual value if your webcam is NOT IR modded and have difficulties to see the leds) cya |
|
Off line |
> Stats
1 user(s) connected during the last 10 minutes (0 member(s) and 1 guest(s)).