A quick build and design of an Astable Multivibrator using PN222 NPN BJT transistors.
Blinking lights are ubiquitous as common amusements in the electronics hobby community. Who doesn’t like Blinky things?
Important design considerations:
-R1/R2 should be sized alongside Rb1 and Rb2 such that the transistors saturate when turned on
-C1 and C2 are charged through Rb1/Rb2, this can allow for computation of on times using the RC charging formula
-setting C1=C2 makes duty cycle adjustments easier as the duty cycle would just be the ratio of Rb1/Rb2 (or the inverse on the opposing transistor)
For more information on how this circuit works, I suggest these video resources
Over the Corner 