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12V / 230V 50Hz square wave inverter with 555

     The DC/AC power inverter can be useful anywhere where you do not have mains outlet, for example a car, trailer or cottage. It can power mains appliances like radios, tape recorders, DVD players, televisions, electric shavers, fluorescent lamps or cell phone charger. The maximum load depends on the transformer, transistors, and the size of the heatsink.
     The source of 50 Hz frequency is a well known 555 timer. The frequency is set by the resistance of Rx and capacitor Cx. As the switches two N-type MOSFETs are used. One is driven directly from the 555 IC, the other through an logic inverter with BC547. 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 12V supply must be sufficiently hard, the supply voltage should be in the range of about 11 - 14V. Use the proper fuse in series with the power input! In products 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 Rx value by 1/6 (from 120k to 100k). 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.

When working with the power inverter be careful - the output voltage is lethal, although input is safe voltage. Output voltage is isolated from the ground, but if you touched both output terminal the voltage is similarly dangerous as the mains voltage. Everything you do at your own risk. Author does not take responsibility for any of your harm.

The schematic of the 12V / 230V 50Hz square wave power inverter with 555.

case TO220 MOSFET pinout - (same for all transistors)

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