This flasher circuit is bit different from other flasher circuits published on buildcircuit.com.
If you have never made any flasher circuit, I recommend these links:
In this project, the NE555 timer is configured in astable mode. You can change the output frequency varying the values of resistance R1, VR1 and C1. When the power is given, all the four LEDs blink at the same time.Free Circuit Design Software: learn to use Editor quickly and easily Cheapest PCB: 10pcs 2-layers 10cm×10cm only $8.21, 3-day build time, 100% E-test