Infrared Remote Control

[walid]

Hi

from this link:  http://home.maine.rr.com/randylinscott/aug98.htm

Iread the following:

The MOD accepts a 40khz IR signal that is modulated at 4 khz. When a signal is received the MOD will go low. The sensitivity of the MOD is set by different values for R1 and C1.

from that I understand that the modulating sig is 4khz and the modulated (carrier) sig is 40khz

Look at the fig below:
the freq of the transmitter sig is calculated from:
f = 1/[0.693 x 0.05 uf x ( 2.2k + 2 x 1K)] =6.871kHz niether 40 nor 4 khz

R1*C1 = 0.4 sec

from where he had that values of freq

[audioguru]

Hi Walid,
Radio Shack doesn't have the specs for the MOD anymore so nobody knows what it does.
Maybe it is just a photodetector that responds to any frequency of IR, then R1 and C1 filter its output.

[walid]

Hi guru

ok, lets agree that Radio Shack doesn't have the specs for the MOD anymore so nobody knows what it does.

i need you help in designing a gate guard using IR MOD as RX and IR diode as Tx
i baught  the RX mod's

i search the net but no circuit satisfied me

i want your help guru so please help me

[audioguru]

Hi Walid,
Replace the unknown MOD rx with a modern TSOP IR receiver module that is common in TVs.
Look at its datasheet. Here is its sales sheet.
Then tune the 555 to make 38kHz or 40kHz to match the new receiver.

[walid]

Hi guru

look at the two figs below,
If i use these circuits as Tx and Rx, and put my idenyified MOD....

that is if i put and aligned these two circuit

[audioguru]

Hi Walid,
We are just guessing about what is inside the MOD. Buy or steal a TSOP from a TV and get its datasheet then you will know what it is and how it works.

[walid]

Try to forget this MOD
I have one and its datasheet, i know its pins and wait your answer to costruct the circuits above

i want to get logic 1 or 0 or any thing else at pin 3 of the nand gate when someone pass, is this possibe or not, or you have a better idea
please tell me

thanks

[audioguru]

I don't know the spec's for your MOD so I don't know if it is sensitive to a certain frequency.
You could make the circuit then experiment with different modulating frequencies to see if it is more sensitive to one.

[walid]

Hi guru

then experiment with different modulating frequencies to see if it is more sensitive to one.

are u mean the Tx freq?
OR u mean the Rx freq through R1 and C1, and if it respond to some freq what the output at pin 3 of the nand gate

thank you very much

[audioguru]

are u mean the Tx freq?

Yes, the frequency of the 555 oscillator.

OR u mean the Rx freq through R1 and C1, and if it respond to some freq what the output at pin 3 of the nand gate

No. R1 and C1 are just a lowpass filter so the output is DC and not the high frequency.

[walid]

thank you guru very much you really helped me