picpicpikapika WROTE:From what I know, when the light intensity is stronger the voltage output of the receiver will be lower (I am using voltage divider circuit for the receiver). It means when a white colour or reflective surface is approaching my transmitter and receiver, my voltage divider output should be decreasing. On the contrary, when a black colour or nonreflective surface is approaching my transmitter and receiver, my voltage divider output should be increasing.
I have tried with the white colour surface and the outcome is ok...it is able to decrease to minimum 3.7V from 4.5V when I put the white colour surface above a certain distance on top of my sensor, and my comparator output was able to act accordingly.
But when I tried to experiment with black colour surface, the voltage change was insignificant, maybe from 4.5V to 4.6V...with the insensitivity of my comparator we can expect nothing will happen
. So I would like to ask how to increase the voltage difference when we are using black colour surface(but I think it is quite impossible since my supply voltage to the receiver is only around 4.8V). Or is there any other methods??
Thanks a lot...
1st, IR receiver is does not depend on light intensity, specifically, it should be infrared intensity. When you say voltage changes, you are referring to?
In your example, white surface changes the voltage from 4.5V to 3.7V as compare to nothing blocking your infrared or in other words, is non reflective objective, correct?
Black surface does not reflect any infrared or less, it is nearly same to nothing is blocking the infrared. Thus, if you compare 2 same condition, there is no significant changes, which is normal. When there is no infrared reflection, it can either be the sensor does not have anything in front of it, or something that cannot reflect infrared, therefore black surface and nothing blocking it is the same condition, or I would say nearly same in your test. The 0.1V changes might be fluctuation of mutlimeter or even noise on the circuit.
If you are using it for line following, it is normal to have only blank and white or 2 colors condition.