Modulater IR detector

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Modulated IR detector

Hello, I'm new to these forums and a beginner in electronics. I am currently building a school project which (I hope) will teach me some practical electronics. The project is about an autonomus toy car which can sense obstacles and avoid them by turning left or right. I am currently working on the proximity sensors and, after searching the net (and these forums) for many many hours, I've come to the conclusion that I need a pulse modulated proximity sensor in order to get rid of false readings.
I can modulate the IR led by the use of the microcontroller which also controls the whole car (it has PWM) but for the receiver I'm stuck with almost nothing. I don't have access to specialized IR receivers (like the Sharp IS471F) and must build a receiver from scratch. I dissected an old computer mouse and extracted the diodes but I'm afraid they aren't up to the job (don't seem too powerful). I've studied some plans but they are so different (from using a microcontroller to using Schmidt inverters I know nothig about). Also, would it require amplification? (the rage is 10 inches)
Sorry for the long message... hope you can help me

 

[Nigel Goodwin]

DON'T try and build an IR receiver from scratch!, it's not worth it - simply take a receiver IC out of an old television or VCR if you can't buy one. It's a three pin chip and works perfectly, building it yourself will require multiple IC's, careful layout, and a fully screened metal casing (and is unlikely to work as well!).