what is the role of two high value resistors with LDR?

[sunnystar]

LDR is connected with a transistor and emiiter of transistor with pot of 10k and and ldr and collector are also connected with two resistors (1.5k and 100k) what is the role of two high value resistors with LDR?

 

[amayilsamy]

Post your schematic. Your statment was not clear..

 

[sunnystar]

ldr ckt attached

 

[LvW]

I suppose, the inventor of the circuit wanted to use a feedback resistor of 101.5 kOhms. Nothing more can be derived from this part of the circuit

 

[sunnystar]

then what is the role of this feedback resistor?

- - - Updated - - -

more clear ckt from datasheet of ldr is attached. tell me the purpose of 2 resistors, pot and transitor

 

[Audioguru]

then what is the role of this feedback resistor?

You wrongly sketched two series feedback resistors from the transistor collector to its base but the circuit has no feedback resistor.

In the clear schematic, the transistor is used as an on-off switch.
1) When dark, the LDR has a very high resistance so the transistor has no base current and stays turned off.
2) When light, the LDR has a low resistance so the transistor has enough base current to be turned on.
3) The 1.5k resistor limits the amount of base current so the LDR and transistor do not blow up.
4) The pot adjusts the sensitivity the circuit has to light brightness.