I need your help to understand more how does this circuit work theory !

 

It could be either 'reflective' or 'interrupted' ,, Emitter to Detector.

Do you have a link or other information on where it is used.?
E

 

http://embedded-lab.com/blog/?p=2425

Its my mini project i have to achieve a tachometer but i first i have to understand this circuit then programming the microcontrollers

 

hi,
Its as the link states, the Emitter IR LED is ON for 1second and the IR Detector receives an increase in reflected IR every time the White piece of paper passes under the faces if the Emitter and Detector.
The transistor at the detector is used to amplify the weak reflected IR pulse voltage to level suitable for the MCU to 'see' as a pulse.

Is this what you are asking.?
E

 

yes.. but i didn't how can i find the value of the resistors ??

 

hi,
The values of the resistors are already shown on the circuit you posted.
example:
4.7K ohms and 68 Ohms

1.8K, 1K and 10K Ohms

The unmarked Diode 'D' is a general purpose signal diode.

 

hi,
The values of the resistors are already shown on the circuit you posted.
example:
4.7K ohms and 68 Ohms

1.8K, 1K and 10K Ohms

The unmarked Diode 'D' is a general purpose signal diode.

hi eric please can u give a tutoriel how to programm with mikroc whats is the instructions i should follow

im beginner

 

hi s-e,

Sorry I don't use 'C', I am a Assembler-saurus.

This link may help.
https://www.google.co.uk/search?q=m...firefox-a&gws_rd=cr&ei=2sDsUo_RC4KXhQeE-4GIBA
E