Re: plz help me: IR remote control & receiver range prob
Normal IR remote controls pulse the LED at 1~2A. That is right, amperes. Thus, for a 5V supply you need about a 3 ohm resistor in series with the LED. Use a transistor that can give you that peak current, either MOSFET or bipolar.
If that still does not solve the problem, use two or more LED's, each with its own series resistor and drive them all at the same time.
If you have a higher voltage available, such as 12V, you can connect the LED's in series and calculate the resistor for about 1A peak, assuming about 2V across each LED. Say you have 4LED's, that is 8V, then you need a 4 ohm resitor in series with them. You can use 3.3 ohm, since the transistor will have some voltage drop across it, too, especially at 1A.
Use a fairly large cap (100-200uF) right across the LED driving circuit, to eliminate the spike sdue to this large current.
Of course, the LED's must not be driven continuously, but in short bursts. The micro should take care of that, stopping the 555, or better yet using an AND gate to disable the signal that drives the transistor. So you feed the output of the 555 to one input of the gate and the other input will be controlled by the micro.
With such high currents and more than one LED, you are very likely to get your range.
Do you think the receiver is OK?
Try it with your TV remote control for range. If that does not give you the correct range, then possibly the receiver is not good enough, either. Of course, you need a scope to look at the output signal, since the micro cannot recognize it.