is it possible to generate 18 different ir frequencies using 18 ir leds(having different limiting resistor in series) and also to detect those frequencies using ir detector??

 

You can modulate the signal going to each LED and then detect the different signals. You cannot change the emitted infrared frequency by changing the diode current.

 

sir how do you suggest i modulate the signal WITHOUT USING MICROCONTROLLER..

 

You need to give the overall picture of what you are trying to do.

 

i have to design an ir transmitter and reciever which i'll use to play tic-tac-toe...i have a 9*9 led matrix on receiver..
i thought by changing current through leds i'll be able to send 18 diff. freq. and on the receiver i'll detect those 18 different detectors..each detector will then display either cross or zero on a particular cell of the 9*9 led matrix...

(i wish i could explain things better)

 

Ok, you're getting there.

Explain how the game is played.
Usually there are nine squares on the board. Each player takes turns marking an X or O on the board.
What do you want to happen?
What is the purpose of the transmitter and receiver?
Where is the transmitter?
Where is the receiver?

You do not need multiple transmitters and receivers. One transmitter and one receiver will do.

But you have to explain a bit more what is the purpose of the transmitter and what is the purpose of the receiver.

(Proper communication comes with practice.)

 

tic tac toe is the X and O game played between 2 players...

there is only one transmitter that'll send X or O..transmitter should also indicate which player turn is it..

at the receiver there is a led matrix which shall display X or O send by the transmitter...receiver should also be able to tell which player has won..

all this should be done without any microcontroller.

 

And what type of keyboard, are they individual switches or a matrix?

 

individual switches

 

Just to make sure, is this the normal tic tac toe with 9 fields, (3x3)?

If it is why are there 9x9 LEDs on the receiver side? Should by 18 LEDs , two for each field, one for "o" the other for "x".

Can you confirm this?

 

it is the normal tic tac toe with 9 fields.

it is upto you to decide the number of leds on receiver side..

 

Ok. You are not giving too much information about your project. I'll just assume you have access to the parts I will refer to... I don't know where you live.

I will further assume that there are two players, each of them having a keypad with 9 switches.

So what you need is an encoder with at least 4 inputs (bits). 9 for the switches and 1 to identify which player pressed the button.

So what I think you could use for the transmitter is:
- an 555 oscillator at 38kHz
- an encoder IC like the http://search.digikey.com/us/en/products/LICAL-ENC-MS001/LICAL-ENC-MS001-ND/701458
- since this one has only 8 data inputs you will need some logic to transform 10 possible "1" states into binary code, maybe with diode logic or an encoder made out of logic gates

For the receiver you will need:
- an infrared receiver like this one: http://search.digikey.com/us/en/products/TSOP39338/751-1390-5-ND/1768192
- a decoder complement to the above mentioned encoder
- some logic to transform the binary to the 10 signals from the transmitter side
- a LED driver
- LEDs


http://pdf1.alldatasheet.com/datasheet-pdf/view/8172/NSC/CD4028.html

 

both the players have to use a single keypad...

 

both the players have to use a single keypad...

Are these keypads connected via a cable or not?

Give as many information as possible when you post something, for example distances between the players, distance to the receiver etc. It's no fun to get all the info piecewise, and you are not helping yourself.

If there is no cable between the player keypads, then you will need two transmitters of course. And if there has to be an indication on each keypad to tell the player who's turn it is then you will need an additional receiver in each player's keypad.

 

there is only one transmitter(or keypad) which both players have to use alternatively.

the distance is less than 2 meters between the transmitter and receiver.

the transmitter should somehow has to indicate which player turn it is...

the receiver has to give the result at the end of each game(this part of the problem is bugging me most, please give an idea about this)..

 

there is only one transmitter(or keypad) which both players have to use alternatively.

the distance is less than 2 meters between the transmitter and receiver.

the transmitter should somehow has to indicate which player turn it is...

the receiver has to give the result at the end of each game(this part of the problem is bugging me most, please give an idea about this)..

I forgot the button that someone pressed needs to be constantly displayed at the receiver side. So you need some RS-latches.
There are only 8 possibilities someone could win. That means you could wire the RS-latch outputs with 8x 3-input AND gates, join their outputs to an OR gate, which in turn drives a LED indicating the winner.

For reliability you will need a feedback from reciver to transmitter (that's another transmitter/receiver pair the other way around) to tell the keypad that the command was received. I wonder why such a feedback is necessary, since both players are watching the receiver side LEDs live while playing, right?

I have nothing to draw now so can't do anything else than describing it.