Hi All,

I am looking for the circuit detect the object within 4 inches to make the output goes high. I have this project and don't not know where to start, so I think you are an expert and need your help.
Please let me know your suggestion or any reference circuit is ok.


Thanks, in advance for your help

Kevin

 

We need to know more about this sensor. What is "the object"? How is it to be distinguished from another object? Under what conditions is the detection to be done in?

There is a great deal of difference between a light source, for example, and a small block of wood.

 

The object such as paper or hand to cross over the sensor, so that make output goes high

 

So the sensor is stationary, and detects a change in light intensity?

 

No, it look like hand and soap dispensing station

 

You might be looking for something like this - http://www.hobbyengineering.com/H1060.html