It is based on cheap TL494, driver IR4426, and two FETs IRFZ44. 88KHz pulses push-pull primary coil of transformer with 2000HM (N-87) ring core. No warming elements thanks to FET driver.
With respect to TL494 datasheet, this circuit won't work with 8V input, but it works with 5V :) Of course, It can not convert 5 to 27V, since it was designed for operating from 9..12V.
