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[on:]

I made an infrared remote control with the arduino,but the transmission distance is only about 80cm. I connect a 100(om) resistance to the receiving tube.I want to extend  the transmission distance.Can I decrease the resistivity of the resistance? Can I amplify
the receiving tube's power?
How  can I do ?
Can you tell me the better method?

[Reply #1 on:]

You need to post a schematic to show what you have, your explanation did not give all the details we need to answer your question.

80cm is a good range for a simple IR setup.

To increase the range you can make the emitter more powerful by reducing the LED resistor, but your IR LED might not be able to take the power so you might burn it out. You can make the receiver more sensitive by increasing the resistor value in line with the sensor.

[Reply #2 on:]

Hi,

I am going to assume you are remote controlling a TV or something? Using the IR remote library.

You need to look at the datasheet for your IR emitter. One I used recently:

 http://cpc.farnell.com/osram/ld271/ir-emitter-5mm-950nm/dp/SC07713?Ntt=SC07713

has a forward current of 100mA at a forward voltage of 1.9V. Which is too much for the meagre 40mA of an Arduino output pin. So you would need to use a transistor, and resistor, in an arrangement like this:

http://www.robotroom.com/Infrared555.html

See the explanation on the link above for deciding on your led current limiting resistor value.

[Reply #3 on:]

You also need to match the IR diode wavelength with the receivers wavelength for maximum range.

There are ten IR wavelengths for IR emitters at this site:-
http://uk.farnell.com/jsp/search/browse.jsp?N=500006+1004339&Ntk=gensearch_001&Ntt=IR+LED&Ntx=mode+matchallpartial

[Reply #4 on:]

Do some research into pulsing the emitter. You can typically pulse an IR LED that can handle 100mA of continuous current at between 0.5 and 1A. The datasheet is essential reading to ensure you supply the correct duty cycle, and an oscilloscope is useful to check the pulse waveform before you allow it near your LED...

[Reply #5 on:]

Do some research into pulsing the emitter

.. at 38kHz