If any one can help me am doing a small project to make a night light sensor with the parts 5v power supply - LED - bc547 transistor - LDR Photoresistor , i am trying to work out what resistor value to use with the LDR , I found a datasheet online but i am still not sure what to look for they seems to be lots of different values , the transistor is from a Arduino kit so i found a datasheet online i thinks it the right one..