Need help regarding my final year project

[abhisinghal2002]

Since the transmitter modulates the light from the laser then its range will be small during the daytime and its receiver's sensistivity pot will need to be turned down to avoid light causing the phototransistor to saturate.

The receiver is an AM detector so it will create loud buzzing at night from street lamps.

It will be extremely difficult to aim the tiny laser beam onto the tiny phototransistor at a distance.

yes u r rite but if we modulate the light with high frequency them i think our problem is solved...
n abt the rx. if we make the rx. as a photodetector...thn thr must not be any problem.....wht u say???????

 

[audioguru]

yes u r rite but if we modulate the light with high frequency them i think our problem is solved...

The laser is Pulse-Position-Modulated with a high frequency. But the receiver is not tuned to the high frequency and doesn't filter out buzzing from street lights. The receiver is too simple, it is just an audio amplifier.

if we make the rx. as a photodetector...thn thr must not be any problem...

The receiver already has a photo-transistor as a photo-detector. A photo-transistor saturates when light shines on it. When it is saturated then it doesn't work.

A good system would FM modulate the high frequency of the laser. The receiver would use a photo-diode in the photovoltaic mode which does not saturate. Automatic gain control would control the gain of the amplifier. A tuned circuit would pass the modulated frequency and reject other interfering frequencies. The receiver circuit would have an FM detector to reject amplitude-modulated interference.

The receiver's photo-diode would still need to be shaded from light which would cover-up the modulated signal it receives.

I don't know how you are going to accurately aim the transmitter at the receiver, unless they are permanently installed.

 

[abhisinghal2002]

The laser is Pulse-Position-Modulated with a high frequency. But the receiver is not tuned to the high frequency and doesn't filter out buzzing from street lights. The receiver is too simple, it is just an audio amplifier.


The receiver already has a photo-transistor as a photo-detector. A photo-transistor saturates when light shines on it. When it is saturated then it doesn't work.

A good system would FM modulate the high frequency of the laser. The receiver would use a photo-diode in the photovoltaic mode which does not saturate. Automatic gain control would control the gain of the amplifier. A tuned circuit would pass the modulated frequency and reject other interfering frequencies. The receiver circuit would have an FM detector to reject amplitude-modulated interference.

The receiver's photo-diode would still need to be shaded from light which would cover-up the modulated signal it receives.

I don't know how you are going to accurately aim the transmitter at the receiver, unless they are permanently installed.

thanx a lot for this information....i'll consult it from my project co-ordinatior.....bytheway...wht could be the best solution as per u????

 

[abhisinghal2002]

As I said, "Easy comes, easy goes..."

You gave him the complete circuit, but he does not know how to read a schemactic.

my freind...i m totally new to this field.....but still i want to know abt that......plz dont mind...if u can't help some one...plz don't disheart any one.....

 

[audioguru]

my freind...i m totally new to this field

It is new to me also. I have never seen a laser communicator circuit before.
When I went to school there weren't any lasers and photo-transistors. You should have learned all about this stuff in the school you have been attending for a few years.

You were given a lousy circuit and I have discussed ways to improve it. It still might not work because a modulated light beam is difficult to aim and detect in daylight.
I am shining my laser pointer outside in daylight right now. Even when it shines on something fairly close to me (2m), I can't see it. At night I can see it shine all the way down the street.

 

[riya karambelkar]

hello everyone!
i am a final year student of ENTC branch.i need your help in finding a good project. can you send me details related to 'tracer with camera','toutch activated speaking robot', prepaid card for 1.petro card 2.shopping 3.internet 4.EB application'
please sir do reply