My main problem in this deign, as you can see, is the mosfet gate driver circuit .

How can the latter be improved, assuming that it cannot oscillate?

Boost converter circuit diagram

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  • \$\begingroup\$ It would help to know what's wrong with it. \$\endgroup\$ – Hearth Dec 6 '18 at 19:36
  • \$\begingroup\$ The fet's gate threshold voltage is 4 volts, but the NE555 outputs about 3.3 volts at a supply voltage of 5V. So, I connected the gate with the npn transistor as shown in the figure; I think if the transistor turns on when the 555's output is high, then the mosfet turns on, and when off, the gate is pulled to ground via the 12k resistor. \$\endgroup\$ – Youssef Sifi Dec 6 '18 at 19:45

Your transistor is put as emitter-follower (common collector) which means that it will amplify current but not voltage. The output voltage will be slightly lower that te input voltage. For voltage amplification, use the common emitter configuration. (Google will be your friend)

Your circuit shows an IRFZ34, which needs a gate volatge of 10V, so it won't work with the 5V you show in your circuit.

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  • \$\begingroup\$ At that drive frequency you're probably better off coming straight off the 555, particularly if it's a CMOS variant and not the bipolar one you have called out. You could maybe get that circuit to work, sort of, by replacing the FET with a logic-level FET. \$\endgroup\$ – TimWescott Dec 6 '18 at 21:46

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