Hi,
Will have some IR-LEDS on a board.
connected as house number , ex 62.

Have heard that the LEDS will have to be pulsed, at 15-20 kHz.
for brighter light ?

Is that correct, or can i just hook up straight to 5v with resistor ?

Rgds ForceMaster

 

You don't have to flash LEDs. You only do that to send information or get a bright pulse with an average power that won't smoke the LED.

 

I'm not sure where did you heard that, the IR led using the frequency is for transmission and avoid affected by the ambient light.

Infrared Sensing and Data Transmission Fundamentals.

 

Ok.
If i connect the IR led as follow.
Will the Resistor R1 be ok with 120 Ohm ?

 

How could you connected 6 IR leds?
If the IR led is 2V/20mA, then it only can connected 5 piece.

 

The LED use 1.5 v 100 ma each

 

If using 80% of 100mA.
R=(12V-9v)/80mA=37.5 Ω, you can use 39Ω.

 

If using 80% of 100mA.
R=(12V-9v)/80mA=37.5 Ω, you can use 39Ω.

@FroceMaster
Note: 39 ohms makes 80 mA and a 3V drop.
3V x 0.08 amps is 0.24 Watts. Too close for comfort on a standard 1/4 watt resistor.
If you already bought a pack of 120 ohm resistors, you can put 3 in parallel to make 40 ohms of resistance and you get 3/4 watt of power handling ability (assuming you are using the common 1/4 watt resistor).

 

You don't have to flash LEDs. You only do that to send information or get a bright pulse with an average power that won't smoke the LED.

I'm sort of wondering; why IRLEDs for a house number?

 

So you can't see it without night vision goggles, of course.

 

So you can't see it without night vision goggles, of course.

Maybe the postman checks all the door numbers through the viewfinder of a digital camera.