I am new on electronics and i was practicing on transistors. I have a working circuit below. The LDR I use allows current and letting LED smoothly based up to amount of darkness. The Voltage after 2.3 k resistor is 0.7 maximum .. All i want to do is to let led run on the darkest moment. So only if it is fully dark the LED must light up .. Not smoothly relative to darkness. What should i do for this ? FIX: the source voltage is 6 Volts
If you want it to accurately switch you really need something more active like a comparator. This circuit will pull around 15mA through your LED when the voltage at the top of the LDR exceeds the voltage set by VR1.
There are other ways to do it with discrete parts, but seriously, you just end up with many more parts and a bigger circuit.