i am working on a proximity sensor which i will later modify.I have TSAL6200 (infrared diodes),TSOP1838(infrared receiver module),NE555 timer and their corresponding datasheets.
I am not familiar with this area so i need some help.In the datasheet for TSOP1838 they specify that:suitable burst length greater or equal 6 cycles/burst what does this mean?
In the TSAL6200 datasheet:Angle of half intensity is (+/-)17 degrees, what does it mean and how is this information useful?
Can i use the 555 timer in the astable mode with a duty cycle less than 50%(say 10%)?

 

You will have better luck using two 555's. One will create the 38KHz "carrier" frequency. The other will modulate that to give you the individual bursts. Bill Marsden's blog has a circuit for that, I believe. Otherwise, there are lots of them on the Internet. Since timing is important, do you have access to an oscilloscope?

John

 

yes i do have access to an oscilloscope

 

6 cycles at 38kHz, 6 peaks on a scope, or to generate with a uC:

Pseudo code:
for (i=0;i<6;i++)
{
LED on
delay 13uS
LED off
delay 13us
}


Angle of half intensity refers to how close to directly at the receiver the transmitter needs to be pointed.

The IR Emitters also have an angle, so combine those two as overlapping "cones" to get an idea of how accurate the Emitter needs to align to the transmitter.