100% brand new and high qualityWork voltage:3-14VPCB size:2.3*2.3cmThe simple flash circuit kit/parts circuit board is made of 1.6MM thick FR4-A plate, and the pads have been treated with tin spraying, which makes the welding easier and the solder joints are more beautiful! It is especially suitable for friends who are beginners in electronics.When the power is turned on, due to the difference of the components, there is always a transistor that is turned on first. We take Q1 as an example to analyze its working principle. Q1 is turned on - Q1 collector voltage drops - D1 is energized to emit light - C1 positive potential is close to zero, because the voltage across the capacitor cannot be abruptly changed - Q2 base is also close to zero potential - Q2 is turned off - D2 does not emit light without electricity; Charge C1 - Q2 base potential rises (over 0.6V) - Q2 turns on - Q2 collector voltage drops - D2 energizes and emits light, at this time the drop of Q2 collector potential causes Q1 base potential to drop through C1 - Q1 is turned off -D1 goes out. In this cycle, Q1 and Q2 are turned on and off in turn, and D1 and D2 keep emitting light in cycles. Changing the capacity of C1 and C2 can change the speed of LED cycle.Package included:PCB board x19014 transistor x2LED blue 5mm x230K resistor x2510ohm resistor x222uf electrolytic capacitor x2dupont wire x2Tips: There are slight difference between the picture and the real item caused by light brightness,hope you can understand.