Mike wanted to build a DC-DC buck converter. He didn’t stop at building one, he wanted to perfect it. So he built it on a breadboard and started experimenting. By exchanging various components and watching a scope for results, he was able to get the results he was looking for.
The buck converter takes a DC input voltage and reduces it by a controllable amount, much like a resistive voltage divider. But unlike your average voltage divider, the buck converter can efficiently supply a substantial output current. In fact, this circuit’s output current should be greater than its input current (on average). And no, that doesn’t violate any laws of physics; the converter’s output power will still be less than its average input power because its output voltage is lower than the voltage at its input.
Via Electronics-Lab.
A very committed approach yet not the most elegant way to breadboard a power supply. One should refer to Jim William’s App notes for better power supply prototyping techniques. The reason, very fast rising edges from the PWM controller even when clocked at 500KHz can start resonance between the gate capacitance and the bread board wires, thereby setting of false edges which will trip the edge detection circuit. This will lead to eventual instability.
http://www.linear.com/designtools/app_notes.php