IR leds and forward voltage drop

[izua]

I'm designing my own remote, for a custom protocol. I know there are a few tricks with using IR leds to save battery, but I'm not really sure which. I know that they can be put in series to increase brightness, for example, but how exactly should this be done?

How do you 'check' them, when you work with IR projects, since you can't see them?

And also, is there an easy way to measure their fwd voltage drop?

 

[Eumel]

At 5V you can put 2 or 3 LEDs in series.

Use a digital or video camera to see them work.

LED in series with 100 Ohm resistor. Increase the voltage of a variable power source until you reach the nominal current e.g. 20 mA. Measure the foreward voltage at the LED with a multimeter.

 

[izua]

would i need a series resistor with the leds seried up? i'm trying to make something really low power.

 

[master_picengineer]

You can consult the led's datasheet, it surely contain the information you need.

 

[izua]

They're cheap bulk leds. No datasheet, that's why i'm asking