Another good demonstration of the LM2577 boost converter IC to upgrade mini-portable fan power. The original circuit of the fast is quite slow and the speed runs as if it was using the battery directly. Since i still need this fan to keep away soldering smokes so i decided to use the LM2577 IC to upgrade the power from 4 volts to 12 volts DC. It turns out to be a perfect upgrade - now i can use my USB 5 Volt port to power up this fan instead of the battery to avoid recharging it over and over again. I have tried a few IC before for example using 555 timer + mosfet and also the Linear Technology LT1172 but the result is not turn as i expected. Although the voltage is upgrade but the amperage output is not satisfactory compare to the LM2577. Apart from that the simplicity of the circuit and also the regulated voltage output is really perfect a small voltage step up.