How to power on infrared LED?

Thread Starter

atifah samuri

Joined Jan 5, 2022
1
I'm doing the project of hand vein visualizer but the vein images result are not appear clearly so I bought the IR LED transmitter and receiver. I tried to power on the LEDs. I don't know why they didn't work but they not light up. Can anyone help or share any circuit for me to try?

WhatsApp Image 2022-01-04 at 11.58.17 PM.jpeg WhatsApp Image 2022-01-05 at 3.46.19 PM.jpeg
 

LowQCab

Joined Nov 6, 2012
2,058
You must have a Current-Limiter of some sort.

This may be as simple as a single Resistor, if You have a stable Power-Supply.

What type of Power-Supply do You have ?

You need to supply the Spec-Sheet-PDF for your Infa-Red-LED.
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ericgibbs

Joined Jan 29, 2010
15,542
hi as,
IR LED transmitter
Is the light output in the human visible range.?

Try this simple test:
Power up the IR LED, use your mobile phone camera, in a darkened room, you should be able to see the glow on the camera, most phones are IR sensitive.
E

BTW: On your setup the Emitter must be pointing towards the Detector, NOT as shown in your image
 

DickCappels

Joined Aug 21, 2008
8,711
You should find that one lead of the LED is shorter than the other. This lead should go to the negative battery terminal, something like this.
1641373882707.png
The dark colored device is the detector. If you are using a 3 volt battery pack, and your LED may be safely and continuously driven at 20 milliamps, we can figure what value resistor you need to use.

The LED voltage is about 1.1 volts;
The battery voltage is about 3.0 volts;
The desired current through the resistor is about 20 milliamps.

The resistors needs to be (3.0V - 1.1 volts)/.020 amps = 100 ohms.

I use the camera test @ericgibbs mentioned in his post #3, but found that some cameras have really good IR filters and had try a second camera before I had success. So, if the first camera or phone doesn't work, try another one.
 
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