IR Led with Boost Converter

[_Nate_]

I have been attempting IR communications, but range is an issue. In a 2-pin led, you must use the digital pins as output, which can not supply enough voltage to the led to provide sufficient range. If I were to use a variable boost converter with the digital pin of the Arduino into the IR led, would this work well?

 

[kellys_eye]

Just use a buffering device (transistor or MOSFET) to switch the IR LED. You can then apply shorter, higher power pulses to the device.

 

[_Nate_]

Just use a buffering device (transistor or MOSFET) to switch the IR LED. You can then apply shorter, higher power pulses to the device.

So will the signal from the digital pin of the arduino match the signal going from the higher voltage source into the led? And will the boost converter work or not?

 

[kellys_eye]

The digital signal from the Arduino will feed to the base of a transistor via a current limiting resistor. The LED will fit in the collector circuit of the transistor with a current limiting resistor connected to whatever DC supply you care to use.

Note that the use of a single transistor in this fashion will INVERT the LED signal - you may have to 'NOT' the digital output to get the right pattern.

Using a 'boost converter' is one way around the issue (if you have a single supply source) but a simple 9V battery would also work - the load isn't significant and the battery would last 'ages'.

You could also add more LEDs to the collector circuit to increase the light output of you wanted.

 

[BobK]

IR LEDs forward voltage is around 1.3 to 1.5V. You do not need to boost voltage. The problem is that the digital output pin cannot provide enough current. Using a transistor lets it operate at a higher current. You can use whatever voltage the Arduino is using, typically 3.3 or 5V, and calculate a resistor to drop that to the needed forward voltage at the operating current. See here:

All About driving LEDs

Bob