This street light controller circuit is designed for around a single IC timer 555. This IC has been used in its bi-stable mode in the circuit. Two LDRs are also used in this circuit to differentiate between day light and dark light. During the day time this bi-stable circuit remains reset by the LDR-2 while in the night time this bi-stable is set by the LDR-1. The output from the timer IC is given to the base of transistor T-2 which drives the relay in turn
Street light connections are given from the N/O contacts of the relay as shown in the figure. The number which can be connected in parllel to this circuit depends directly upon the load rating of the relay contacts.