Student Final Project Need help

[mackrackit]

If you have built a video transmitter a 40KHz oscillator should be a piece of cake. What do you need a micro controller for?

When the IR receiver receives an input, that could then start the 40KHz oscillator via transistor to an IR LED to extend the range.

Again, if you have built the video components, why do you have to ask about IR?

Or, have you got a bunch of stuff pre-built and ran a few cables?

[sougata]

Hi,

He is actually querying for the IR extender part. Its good that he wants to use a microcontroller. Otherwise he could just use a 555 timer IC to generate the 40KHz for lighting up his IR LEDs. Marco please note you need a duty cycle between 10 and 20 % to get effective IR beaming. And your receiver expects that. That is receivers (depends on which one used) may fail at a 50% duty cycle.

For the 555 thing try this link http://wolfstone.halloweenhost.com/T...TimerCalc.html also most receivers are centered around 38KHz not 40KHz. Use the reset pin (4) of 555 to switch on-off your IR.

For a PIC choose any one that has got a Hardware PWM model and few lines of code should. A quick recall 16F819 , internal oscillator HPWM.

P.S. - Marco it is high time to learn a micro. If your college does not have a copy of PBP ask them to get one. You will find many people here extending there support.

[mackrackit]

Hi,

He is actually querying for the IR extender part.

This I know.

My point was ... If the student can build a video transmitter, and yes, I do not think he is using 40KHz for the video. Why does he need a micro controller?

I still think the easy way is to have a photo-diode receiver trigger a transistor ( or 555 ) then out to IR led. Duty cycle and frequency does not change. True extender. The store bought receiver on the equipment will never know the difference.

Be glad to help with a micro solution, but things will get complicated for a first time project.

I would imagine that the remote has more than one function to send? How many? Now if pulsin this pulin that then pwm this and that.

It might help to think of a linear amplifier, but with no amp. Same signal in as out.

[mackrackit]

This is a link to what I am talking about.

http://www.zen22142.zen.co.uk/Circui...face/irext.htm

I have not tried this circuit, but it is the right concept.