Automatic night lamp using PNP transistor,and LDR

This is an automatic night lamp circuit diagram, made using a pnp transistor, a dark detector
Here ldr is light dependent resistor, p1 is a potentiometer (100kohm-500kohm).
and the pnp transistor is working as a switch in this circuit. Consider the following diagram to 
understand the functioning of pnp as a switch.

PNP Transistor as a Switch

We can also use PNP transistors as switches, the difference this time is that the load is connected to ground (0v) and the PNP transistor switches power to it. To turn the PNP transistor as a switch "ON" the Base terminal is connected to ground or zero volts (LOW) as shown.
























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