automatic toll tax 89c51 help.......... needed

[muralistarshine]

hi this is my final year project.... i needed to build automatic toll tax system using ir sensors ......can we directly connect tsop1738 to 8051 ???and how this ir transmitter and reciever circuit works??i am using 555 for ir transmitter and tsop 1738 in reciever section??? what happens by functionality plz help me......... i am a bit confused

 

[rikilshah]

TSOP 1738 gives TTL output so you can connect it directly to controller.Don't remember to connect out put capacitor to avoid noise which is depicted in it's datasheet.
You can find working of circuit by simple googling.But in short 555 modulates IR light at 38 Khz.Now TSOP 1738 has inbuilt Bandpass filter which receives only frequency between 36-39 Khz.So when ever any frequency in this band is received it gives output 0 otherwise it remain high normally.

 

[muralistarshine]

tsop 1738 with 555 based ir led range that it can be made worked out and also once it is interrupted it remains low and

also............
When I focus the IR LED to the receiver it will make low output. When I take the IR LED to another side receiver will make high output that is correct.

The only problem is

When I again focus the IR LED to the receiver it won’t make low it stays as high. So again I have to break the beam (cover) by hand so it will make low as earlier. That is my problem I don’t know what’s happening here.

plz help me outttttttttttttttttttttttt

 

[rikilshah]

If possible try to post your circuit.
Check again the current in IR led and test TSOP 1738 with TV remote.

 

[rushi53]

The only problem is
When I again focus the IR LED to the receiver it won’t make low it stays as high. So again I have to break the beam (cover) by hand so it will make low as earlier. That is my problem I don’t know what’s happening here.

This is very common problem.
Solution: You have to set the output freq of 555 = 38KHZ. For this use a potentiometer instead of fixed resistance.
Then place Transmitter in front of Receiver, now slowly vary the potentiometer untill the output of TSOP is low.

Post your 555 circuit here. Also post values of Ra, Rb, C used in 555 circuit.

 

[aju...]

Help me....

plz..send me a ckt. diag. of automatic toll tax using 89c51...

 

[swati88]

swati88

plz send me the ciruit digram and related information for automatic toll tax.

 

[hiten09]

plz send me the circuit diag of automatic toll tax controller using 89c51

plz send me the circuit diag of automatic toll tax controller using 89c51...if possible then plz send pcb layout also.........my id is hitensingh09@gmail.com