Here is an interesting circuit of 1.5 V to 20 V converter Circuit from an ordinary 1.5V AA sized cell. At the heart of this circuit is transistor 2n2222 you can use S9013.
This charger circuit will step up the voltage from 1.5V to 5V DC. The circuit uses only an AA or AAA 1.5v battery (1V to 2.4V). The charger is composed of simple oscillator, a rectifier, and voltage regulator.
The feedback winding F is composed 5 turns of #30 AWG magnetic wire and main winding P is composed of 6 turns of #24 AWG wire.
The windings are not critical, and you can experiment using different number of turns. If ever the charger doesn’t have any output, try to reverse the winding connection.