Three led flasher by 3 transistor astable multivibrator

 

The Flash rate of LED1-LED3 in each frequencies output are easily changed simply by changing one, or three of the timing capacitors (C1,C2,C3) which each capacitors not need same capacitances.
The Resistors-10K are used to bias transistor conducting.
And we insert VR1-10K-potentiometer to control base current of transistors which importance them are used to simply adjusts the flash rate.
And each the 470 ohms resistors is used to control current flow through or limits current to each LEDs.
We assemble all components into the breadboard as video below.
We will see that, the LEDs alternately flash ON and OFF about once per second, always two LED will glow each time.
The components List
Q1-Q3____CS9013__500mA 30V NPN transistor______= 3 pcs.
C1-C3____47uF 35V Electrolyte capacitors__________= 3 pcs.
VR1___10K (B) Potentiometer single ________________ = 1 pcs.
R4-R6_____470 ohms ___1/4watts resistors___________ = 3 pcs.
R1-R3______10K ____1/4 watts Resistors____________ = 3 pcs.
LED1-LED3___LED as you wants____________________ = 3 pcs.
PCB or bread board.