Drive IR led 100Ma with transistor

Other Hardware General Electronics
1

Hi everyone I've got an IR LED which I'm using for a project to control air conditioning, but the Range is terrible. I've read that the Arduino can only put out 30 Ma from a digital pin, and thus a transistor is needed for higher applications. I have never use a transistor before but I have used mofets and I assume the process is the same ?

Can someone draw me the most basic way I can connect a resistor and transistor to a pwm pin on my Arduino to get around 100 Ma please. Or at least a recommended transistor and a description of what connectshe to what.

2

https://www.gammon.com.au/forum/?id=12737&reply=3#reply3

And its mA. m for milli, M for mega, A for amps, a is not the symbol for amps.

3

Look at this answer in this forum:

Powering LED's from external source?
Apr 19, 2009, 02:16 am Last Edit: Apr 19, 2009, 02:18 am by gust0208 Reason: 1

This will get you started. Actually you can google "Powering LED's from external source" and it will take you right there.

FYI, 2n2222 is real popular and cheap for what I think you want to do.

4

Ok i shall get a transistor now, my store has bc337 transistors they look the same as a 2n2222 ?

5

bc337 transistors they look the same as a 2n2222

Check the Pinout.

BC transistors are CBE, typically
2N2222 or 2N3904 are EBC

... when looking at the flat side, pins down :wink:

6

Some transistors are even available in two pinouts (very annoying), but yes, the datasheet should
always be checked for the pinout...

7

And if you buy one of those cheapo-parts-testers made in china... it will SHOW you which pins are E B C.

8

You can also consider getting an IR led with a narrow "viewing angle" so the beam is more strongly focused and is, therefore, likely to have a better performance.
Farnell stock a range from 3 degrees to over 150 degrees. Look for IR emitters.
I'd consider 10 degrees or below for such an application where you require some range, and are able to direct the beam towards the receiver with reasonable accuracy.