I am looking to assemble a power supply with an output of roughly 600 watts. One of the components required for such an apparatus is a 40 kVDC, 20 mA flyback transformer that I managed to find and hack in order to work for this specific purpose. I noticed that in this process, many people were calling for a transistor based circuit that seemed to be for transformer feedback. This was the circuit that I was considering:

https://qph.fs.quoracdn.net/main-qimg-b6b61f0253f7c878d9e9a8507053aa42-c

Thus, I was first of all curious if such a circuit would be required for the flyback. If so, I was also curious if the shown parts and their descriptions would be capable of withstanding an input of 60 VDC and 10 A. Thank you.