[SOLVED] I'm facing problem regarding sensor circuitry?

[shantilal.s50]

Hello frnds,
I'm a beginner in the robotic field, I'm using a LDR sensor @receiver with White LED as a transmitter Ckt(Proximity sensor)
and I'm facing a very uncommon problem in my receiver sensor (Proteus simulated Design is attached below )that when I design this Ckt on Bread board then @ critical Values of Potentiometer i.e. 0 ohm & 20k ohm , the complete ckt shuts down. why so happens??

Note: I found this problem when I'm using Two or more than two sensors.

The proteus design of my sensor ckt is working and attached below.

 

[Usama Siddiqui]

the problem is that when you actually sets your potentiometer to 0,the path actually sinks all the current to the ground therefore the transistor remains in cutoff state,secondly simply invert the position of your LDR with potentiometer.it will work

 

[FvM]

the complete ckt shuts down

Hard to guess the actual meaning of vague descriptions like this.

 

[shantilal.s50]

Alright Usama,

I'm agree with you but happens in second case when value of pot. is maximum i.e. 20k ohm.

Do you have any idea!!!

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@Fvm

Sir,
Actually I'm working with a small project named Collision Avoidance Robot in which two LDR based sensors(Mentioned in the main post) are used One at front side and another sensor at the Back side of a toy car(Having a DC Motor).

I'm controlling the motion(F/w, B/w or stop) of this car by interfacing the sensors o/p to the H-Bridge ckt and hence control the motion of car with the o/p of H-Bridge.
Know I'm facing the problem at this stage and also, just before interfacing the sensors o/p with H-Bridge ckt.

 

[Usama Siddiqui]

check the potential at 20k it will be less then the nominal required maybe becoz of the current passing through ldr. and use a comparator ic lm324(easily available) it will do you job far more easily