infra-red remote control ...

hi all ;


i have got a strange problem on infra-red remote control , my problem is short range af transmitter ,

i have desigend a receiver and transmitter ( infra-red ) , using 2 89c2051 , one as sender and one as receiver .

i connected a LED to the output of infre-red receiver ( 38 kH ) , when i turn my transmiter on , it makes some pulses ( 38kH ) to infre-red LED sender and the LED connected to output of infra-red receiver turns on and off according to the pulses of transmiter , but when i go far for more than 4 meters , it doesn't recieve any pulse !! , so i used our home TV remote conrol as transmitter , it's range is about 15 meters and the same receiver !! i changed infra-red LED's of my made transmitter and TV's with each other , but the result was like before , i don't know where's the problem , my transmiter's voltage is 5V but TV's is 3V , i have used a transistor in output too , but don't know why mine is short range !! can it be because of special pulses giving to infra-red LED ?

for example , should it be 5 uS high and 21uS low or other values ???!
my wave is 13uS high and 13uS low , ( 50% duty cycle ) period = 26 uS , frequency is about 38.461 kH .
please share your experience with me ,
thanks you all .

for increasing the Ir range you have to modify your output stage:

1. you heve to increase the IR transmitter current at hundred of mA (depending of the catalogue specs)

2. You have to make for amp stage a power buffer (an RC group, C will maintain the battery power during Ton, and will charging thru R during Toff)

3. You have to decrease Ton time to obtain a medium consumpted power according catalog speciffication for IR transmitter.

Hope this help,
//a

yes , thank your for your help , but in receiver's datasheet it's not said how long is the allowed minimume Ton !!
i want to know the minimume allowed time for better battery life ...

with 2248 and 2249 or 2250 ,you can control 10-16 signal control
2248 this is the transmitter
2249,2250 is the receiver

You should use a pair of 2248-2249. In order to control another objects, you see carefully about signal waveform & driver of 2248

plz explain ur problem a little more