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.
For All Your PCB Need, One-stop PCB Solution Services Appear
EasyEDA: free PCB design tool, 200,000+ engineers are using
PCBs: 10pcs 2-layer 10x10cm only $8.21, on-time global shipping
Components: save up to 50% , combine shipment with PCBs