Hello all I have a fairly straight forward question about transistors. I am an engineer focusing in power generation systems, and currently working on designing a test inverter for a new type of DC generator. I have extensive knowledge of DC circuits and power systems, however this is my first foray into the AC realm. I have already designed all required circuitry for the inverter, sans the switching mechanism. I currently have relays in place to handle the switching however they are not reliable enough for me to use. So I have been pointed in the direction of using transistors in their place, and would like to know if anyone has any pointers of where to start looking. On to specs of the design, the inverter will be a 1 to 1 inverter meaning there will be no transformer in use. The output Voltage of the power source is 170Volts and the maximum output current is 42 Amps. The current design is using relays to flip the DC power source inputs from positive to negative to create a square wave voltage. This square wave voltage is then passed through two different 3 pole filters the first being a shunt band-pass filter and the second being a low-pass LC filter. These filters turn the square wave into a suitable sine wave output. I have constructed a simple 60Hz oscillator circuit out of a NE555 Ti timer chip. The output of the chip is boosted and then used to trigger the relays to switch. I would like help on using transistors to directly switch the output of the generator instead of the relays. The maximum DC power output of the generator is 7,200 Watts. Maximum Power output of the inverter needs to be at the very least 3,500 Watts. So you guys know I am very aware of the safety issues when dealing with power levels and output levels of this nature. Also the entire project is being performed in a laboratory environment, with the latest in safety equipment and regulations.