automatic switching of street lights by using ldr and relay Answered
hey me and my friends were ton a project of automatic switching of a street light depending on the brightness in the surroundings.
so we decided to use an ldr(light dependent resistor). here in this circuit ldr has low resistance in brightness(only few ohms) and very high resistance in complete darkness(nearly 1M ohm).so the transistor Q1 becomes on in day times and Q2 becomes off and hence the relay remains in NC(normally closed) state and the lamp will not glow. at night the transistor Q1 becomes OFF and Q2 becomes ON and hence the relay goes to NO(normally open) state and the lamp glows.and the sensitivity of the device can be varied by adjusting the potentiometer
now i just want to know are there any defects in this circuit so can u please help me in knowing the drawbacks and correcting them
and i want to know whether i can connect a relay in place of a fuse as shown at bottom