Why do real IR remotes work so well compared to my experimental device?

[SeanB]

Bananas, I just finished the last one in the bunch.

Back to the OP consideration, I have often seen IR transmitters with limited power using a very nice trick, having a local RC circuit with a typical value 10R resistor and a 1000uF capacitor feeding the LED power, so that you can have a very high transmit power, but the current drawn from the supply is limited by the resistor, so it is low enough not to reset the MCU because of the high internal resistance of the main supply. You do need though to keep duty cycle low, which is easy on an IR transmitter as there even with a key pressed continuously most IR transmitter protocols are going to have a low sub 10% duty cycle.

[dentaku]

Random ir leds ? They may be the wrong wavelength
Or you are not pumping enough juice through tem

Yes, like I said in my last post it works well now that I tried controlling the IR LED with a transistor and a 9V battery instead of just powering it directly from the 5V of the Arduino which couldn't safely supply the needed current anyway.

Well hold on there, the Arduino IO *pin* might not be able to supply the current, but what is providing the 5V to the system? Are you saying that can't supply about a 100mA more? You could clean up the whole thing by just using the available 5V supply rail.

You're right, it doesn't matter how much current the IO pin can safely supply anymore because it's just connected to the base of the transistor. I don't know why I didn't think of that. An UNOs 5V rail can safely supply 200mA according to http://playground.arduino.cc/Main/ArduinoPinCurrentLimitations

[dentaku]

I've done some testing and a 12ohm resistor works well when powering the IR LED from the +5V rail of the Arduino.
The TV picks up the signal just fine without having to point the emitter perfectly in the right direction.

I would have never dared to use a 12ohm resistor on an LED before reading some of your answers but I guess IR LEDs pulsed very quickly are quite different than just constantly lighting regular LEDs.

[Alex Eisenhut]

I've done some testing and a 12ohm resistor works well when powering the IR LED from the +5V rail of the Arduino.
The TV picks up the signal just fine without having to point the emitter perfectly in the right direction.

I would have never dared to use a 12ohm resistor on an LED before reading some of your answers but I guess IR LEDs pulsed very quickly are quite different than just constantly lighting regular LEDs.

Well you can't *see* what's going on, you can't tell if it's working, not working, or if you just blew it up. Radio Shack, RIP, used to sell this



it's magic, you charge it up with visible light from a fluorescent or sunlight, then that pink strip lights up in the presence of IR. I can't find a picture of it glowing.

But now that electronic cameras are everywhere, you just use that. When I bought that strip, the only video camera I had was a B/W Panasonic tube camera hooked up to my Amiga...

I'm old.

[dentaku]

I've done some testing and a 12ohm resistor works well when powering the IR LED from the +5V rail of the Arduino.
The TV picks up the signal just fine without having to point the emitter perfectly in the right direction.

I would have never dared to use a 12ohm resistor on an LED before reading some of your answers but I guess IR LEDs pulsed very quickly are quite different than just constantly lighting regular LEDs.

Well you can't *see* what's going on, you can't tell if it's working, not working, or if you just blew it up. Radio Shack, RIP, used to sell this



it's magic, you charge it up with visible light from a fluorescent or sunlight, then that pink strip lights up in the presence of IR. I can't find a picture of it glowing.

But now that electronic cameras are everywhere, you just use that. When I bought that strip, the only video camera I had was a B/W Panasonic tube camera hooked up to my Amiga...

I'm old.

I pointed my brother's Samsung Galaxy phone at it and compared it to a Bell remote.

I guess I'm old too because I've had a Vic-20, C-64 and Amiga 500

[Wim_L]

I've done some testing and a 12ohm resistor works well when powering the IR LED from the +5V rail of the Arduino.
The TV picks up the signal just fine without having to point the emitter perfectly in the right direction.

I would have never dared to use a 12ohm resistor on an LED before reading some of your answers but I guess IR LEDs pulsed very quickly are quite different than just constantly lighting regular LEDs.

It's not specific to IR LEDs. Regular visible or UV LEDs can also be used with short high-current pulses.