Step up booster

If you want to speed things up swap out the NPN BJT for an nMOSFET with high width. EveryCircuit BJTs aren't really appropriate for high current needs.

Any trannie here isn't good from one crucial aspect. Here one transistor is a model of single Die device. Power mos for example a hexfet series is a one thousand small trannies acting mostly parallel. Factors are statd as sum of all smaller values such as widht or lenght. And believe me one device with channel lenght of 700um do not behave even similar to a 700 small devices having 1um widht . And this single one behave dramatically bad compared to this one divided. Similar situation but not so crazy rated is in bjt's where power ones are composed from 2 OR 3 single devices a one example is 2n3055 as i remember it was a duo combo created and hits market in early 60, s brw.