We always appreciate when someone takes the time to build something and then demonstrates what different design choices impact using the real hardware. Sure, you can work out the math and do simulations, but there’s something about having real hardware that makes it tangible. [Julian Ilett] recently posted two videos that fit this description. He built a buck converter and made measurements about its efficiency using different configurations.
The test setup is simple. He monitors the drive PWM with a scope and has power meters on the input and output. That makes it easy to measure the efficiency since it is just the ratio of the power output to input. You can see the two videos, below.
It is interesting to see that the various design options do change the efficiency, but perhaps not by as much as you would think. The range wound up being 72% to 84% — unless you count removing the low-side device which led to 0% efficiency because the circuit won’t work without it.
If you want a refresher on how a buck converter — that is, a DC to DC converter that reduces a higher input voltage to the desired voltage — works we had a good brief video about that recently. If you want a little more whiteboarding and explanation, you might enjoy the Sparkfun video on the same topic.