Blocking oscillator converting 12 volts DC-220 volts AC - uses two common collector power transistors to switch DC in alternate directions through transformer and uses magnetic base switching

摘要

The circuit uses two 2N 3055 power transistors connected in common collector configuration. The transistor are used to switch the direction of current from a 12V DC source in alternate directions through the primary of a transformer to give a sinusoidal 220 V alternating output at the transformer secondary. The transistors (TR1,TR2) conduct alternately and have part of the transformer prinary (B1,B2) connected between their emitters and earth. Another section of the primary winding (A1, A2) is connected between emitter and base of the transistors causing them to conduct in alternation. An offset resistor (R1) between collector and base of one transistor ensures starting of the inverter, and the turns ratios on the primary set the oscillating frequency.