hi. i have attached the circuit. sorry i have not made it properly.
here my idea is that when the light of led does not fall on the LDR , the emitter output is high(2.5 V). so comparator will compare it with 1.5 V and result is Vcc. now when light falls on LDR, its resistance is decreased and emitter output is low(0.7 V). so my comparator will give 0 V as output.
now the problem is that when the +ve and -ve wires of multimeter are touched to output pin 2 and gnd to measure voltage, the output changes suddenly.the high output becomes low.