Class : Apprenti
Posts : 2
Registered on : 26/09/2016
Hello, and thanks for this great website! I'm trying to build a head tracking clip with 3x SFH485P LEDs. I've tried making the circuit as instructed on this site:
I've tried both a parallel build with 47 ohm resistors, and a serial build with anything from 10 - 470 ohms, both on a 5V power supply or 3x AA batteries, and the result is that the leds are super bright! Way too bright. My webcam is a PS2 eyetoy with the IR filter removed. The webcam see the LEDs as just one large mass of light.
However, if I supply only 3V through 2xAAA batteries, or 3.3V through a power supply, in a serial circuit, the LEDs look like perfect little spots on the webcam.
I'm still learning electronics, and can't figure out what to do. Is it ok to run 3 of these LEDs on 3V? The forward voltage is supposed to be 1.5V on these, and from what I've read you should then supply at least 4.5V for 3 LEDs. So do I build it with 3V, or do I use 5V and a large resistor? I tried 470 ohms, serial circuit, and that was close to ok, but the LEDs still blended together a bit.
Or maybe my webcam is picking up too much IR light?
Class : Légende du Forum
Posts : 450
Registered on : 02/01/2013
I should stick to 5 volt(usb-power).The reason is that it is easy to get a powersupply for your setup.You can choose a smartphone charger or a backup battery wit usb output.With normal batteries the voltage will drop slowly when you use them.
For 5volts you can use 10 ohm resistor with serial setup for less bright and 6,7 ohm if they need to be brighter.
Put you say they are to bright already, what kind of daylight filter are you using?
Did you also disable all the automatic functions?