Some time ago, I reverse-engineered a low-cost inverter made by Vector Mfg. (now Black & Decker). It uses a classic 2-BJT astable multivibrator (AMV) but with a circuit design twist, as shown below.

In the classic configuration and most variants of the astable 555 multivibrator circuit, the timing characteristics are based on the charging and discharging of a capacitor. However, it can be argued ...