IR

[Dr_Doggy]

I was reading that we put tv remotes on a 40khz signal so we can burst it, emitting more light at a time, thus going farther.

1)Is that 50% duty cycle?

2)could this work with a pocket laser?

3)IR led with a voltage rating of X-volts(DC), how much higher do/can i raise my burst voltage?

4) what is the best IR transmitter circuit i can use, just a basic 555 + transistor + LED....(how do i calc supply voltage)?

5) what is the best IR receiver to use, could I use an op-amp(or band filter) to filter out the ambiant room noise thus increasing my 40khz carrier signal?

thnx!

 

[Nigel Goodwin]

You were reading (or understanding) wrongly - the 40KHz modulation is to give immunity from interference, the bursts of 40KHz have a low duty cycle to allow high pulse currents. Try reading my PIC IR tutorial, for a receiver use one of the many IR receiver IC's, they give excellent performance, easily exceeding 10m.

 

[Dr_Doggy]

thnx nigel, that does make more sense, however i am not using serial comm, so my data packs are different, even though i can still use the carrier frequency, is there a way to measure the increase in bursts,,,

ie. if i use a 3v IR led(DC)nominally, then switch to a 40Khz w. 10% duty cycle does that mean i can now use 30v ? ........or should i say amps?

 

[Nigel Goodwin]

thnx nigel, that does make more sense, however i am not using serial comm, so my data packs are different, even though i can still use the carrier frequency, is there a way to measure the increase in bursts,,,

ie. if i use a 3v IR led(DC)nominally, then switch to a 40Khz w. 10% duty cycle does that mean i can now use 30v ? ........or should i say amps?

It's the current that matters, applying 30V directly to an LED would instantly destroy it.

You need to explain EXACTLY what you are trying to do, the repetition rate of the data bursts is pretty crucial.

 

[Dr_Doggy]

well 2 things.....
1) I got some Ir led's rated at 100mW, 30mA constant,, 1A@300pps for 10us , so i get that now, so its not a problem,

but I have a IR Laser diode, but it has no datasheet, right now, i am running it directly from a 555 timer servo PWM circuit, can I "burst" with the laser too?

 

[audioguru]

I think you must go back to school for a couple of years to learn English and to learn about the basics of electronics.

 

[Dr_Doggy]

ENGLISH is for jerks, and my school came out of a cracker jack box!

 

[canadaelk]

That explains that, I think. E

 

[Dr_Doggy]

and which part dont i knwo ? I'd learn faster if you explain things, how bout this u buy my edu an i go so i can speak pretty boy too

hey HERES A QUESTION : u drink your tea with you pinky out, don't you, PUNK!?

 

[canadaelk]

Buy a book. Read it! I am an ESL (you know what that is, don't you?)
And, about your post #7: You are in a box allright, but you ain't no cracker jack!
E

 

[Dr_Doggy]

well then go bak to your wheres waldo