For L1 i used 25 thurns and for L2 i used 50 thurns.
The thurns of the secunadry determine the output voltage.
From an 9V batery the transsitor will probobly not overheat.The R1 is heating a lot,so use an big resistor.Or you can use an graphite pencil mine for it.
Yea be careful not to overcharge it.You cod make an cap full detection cirucit.You can shut this cirucit down by disconectiong the R1(The lest curent to be swicthed)
Also this cirucit outputs AC at +20kHz.So stick an didoe on to make it DC for cap charging.