This is the more modern version of the 12V / 230V DC/AC inverter. It is controlled by IR2153 circuit. This integrated circuit is better than the 555, because it has two outputs specifically designed for driving MOSFETs, deadtime IR2153 protection against undervoltage (low supply voltage). This is good for a high efficiency and reliability. Transformer is a mains one with two secondary windings 12V and must be designed for the maximum load required. The heat sink of the two power transistors must have heatsink according to the load. They are mounted on isolation pads. You can also use separate heatsink for each transistor and no isolation pads, but then the heatsinks must not touch each other and must not be grounded. The source must be sufficiently hard, the supply voltage should be in the range of 9 - 14V. If the supply voltage is lower than 9V circuit IR2153 is turned off, preventing damage to the battery, inverter or powered unit. The supply is suitable fuse. In appliances that are not dependent on the frequency of 50Hz, it is possible to use a higher frequency, about 100 - 300Hz. This reduces the standby power. The frequency can be adjusted by changing the values of Rx and Cx. It is also easy to modify the system from 50Hz to 60Hz just by reducing the oscillator R value by 1/6 (from 270k to cca 220k). MOSFET can be IRFZ44 for loads up to 200W, IRFZ48 up to 350W or IRF3205 up to 600W. For output above 600 watts is possible to combine multiple transistors IRF3205 in parallel. Very good parameters has also IRF1405. This type of DC/AC power inverter has non-stabilized output voltage, square wave.