A laser audio transmitter... Problem

[detoknight]

Im doing a project based on : ECE 4760 Final Project: Laser Audio Transmitter
Its a wireless audio transmitter and reciever using laser and photo diodes.
I have simplified the circuit, and here are the ckt diagrams for transmitter and reciever respectively:



However I am not getting a good output.
When i tried to give a sine wave as i/p,
In the Reciever end, the output is getting clipped for some reason.

Can u give suggestions for what to do?
I can only use the above components.
What change should i do to the ckt?

 

[milind.a.kulkarni]

I think there are two things to it one is what is input volatage that you get from Photo detector..... and second is your feedback resistors are designed to give the corresponding outputs are not....I will recommand you have both feed back resistor to be pot and fine tune your system....the third is you can go more voltage for OPAMP like 12v or 15v in case you don't want to have clipping....as rail to rail voltage is depend up the vcc

 

[detoknight]

I think there are two things to it one is what is input volatage that you get from Photo detector..... and second is your feedback resistors are designed to give the corresponding outputs are not....I will recommand you have both feed back resistor to be pot and fine tune your system....the third is you can go more voltage for OPAMP like 12v or 15v in case you don't want to have clipping....as rail to rail voltage is depend up the vcc

Thanks for the quick reply. I will try ur suggestions as soon as i can. But the component description of the IC says it cannot withstand the voltage range u have specified.
I am an amateur and i took this ckt from a different project and modified it. will the ckt theoretically, be able to do the transmit and receive an audio signal??

 

[milind.a.kulkarni]

one small question....are u getting negative cycle chiped.....
then possibly u go for ua741 from st micro .....but it require......+vcc and -vcc.....

Good luck

 

[Audioguru]

The laser diode is backwards and has no current-limiting.
The opamps must be biased at half the supply voltage.
The photo-diodes also must be biased.

 

[ALERTLINKS]

ECE 4760 Final Project: Laser Audio Transmitter
As pointed out in post above.

Try biasing like this.
put a 47 ohm series resistor to laser diode and adjust output of ic near 5V usig 10K variable resistor in transmitter section.