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Sunday, July 15, 2012

Very simple 5v to 65v DC boost converter!

The circuit is derived from the well known DC boost converter circuit using 2 transistors to switch the MOSFET (PNP and NPN). The RC (10nF and 1K) decides the frequency. Higher capacitance gives lower frequency and lower resistance gives higher frequency. The circuit works but im not sure if its the best way to build a DC boost converter. However its the simplest i could think of.

Using iCircuit App for iPhone (Shadi Soundation 2012)


  1. The collector of the transistor is missing a collector load resistor. The gate of the MOSFET does not draw any current, and the way it is the collector current has nowhere to go, and the transistor can't function properly, if at all. I would start with a 1k from collector to ground, and see if the waveform has fast risetime. It could be slow risetime because the gate of the MOSFET has a lot of capacitance which has to be discharged. Thanks.

  2. principally you are right about the collector resistor (exactly what i did in a later version of the circuit) .. However, I wonder why does it work despite the missing resistor :-) !!?? About the gate capacitance of the MOSFET .. I really dont know which MOSFET that was ... and how would I discharge it (a resistor between gate and GND !!?? )!? Thanks again for the feedback

  3. Does the voltage drop while in a load??