I know that the LM339 Comparator IC has a current sinking output. I made a small night lamp with the help of a LDR and an LM339 comparator IC. It worked properly.
The LDR connected to the inverting input (pin 4) of the IC and a reference voltage was supplied at the non-inverting input (pin 5) from Vcc through a resistor. This way the comparator compares the value of the LDR with the reference voltage and sets the output accordingly.
I just implemented a part of it (not the switches and all. I have my LDR in place of that) in my own circuit which uses an LDR. Its taken from an answer on another thread. That entire answer can be found here: https://electronics.stackexchange.com/a/283533/127782
I realize that in order to turn on the transistor I need a current source from the output pins of the LM339. How would I achieve that ? If that's not possible, or I have misunderstood something, can you just tell me how to operate the transistor in this circuit ?