This circuit will provide a very stable "Square Wave" Output Voltage. Frequency of operation is determined by a pot and is normally set to 50Hz/60 Hz. Various "off the shelf" transformers can be used. Or Custom wind your own FOR BEST RESULTS. Additional MosFets can be paralleled for higher power. It is recommended to Have a "Fuse" in the Power Line and to always have a "Load connected", while power is being applied. The Fuse should be rated at 32 volts and should be aproximately 10 Amps per 100 watts of output. The Power leads must be heavy enough wire to handle this High Current Draw!
Appropriate Heat Sinks Should be used on the RFP50N06 Fets. These Fets are rated at 50 Amps and 60 Volts.
** Other types of Mosfets can be substituted if you wish.
The LT1013 offers better drive that the LM358, but its your choice.
The Power transformer must be capable of handling the chosen wattage output.
Also, Appropriate Heat Sinks are Necessary on the Mos-Fets.
Using a rebuilt Microwave transformer as shown below, it should handle about 500 watts Maximum.
It requires about 18 turn Center-Tapped on the primary.
To handle 500 watts would require using a 5 AWG wire. Pretty Heavy Stuff, but so is the current draw at that power.