u/elpechos

I got tired of the "SMPS bad" orthodoxy in audio circles so I decided to actually measure what's going on and design a proper filter for a laptop brick.

I prototype and test a two stage filter design: a high-frequency LC filter followed by a capacitance multiplier.

The result is sub 1.6 mVpp ripple from a laptop brick that started out with a shocking 584 mVpp noise.

I've documented the whole process here:

https://siliconjunction.top/2026/04/21/stop-hating-smps-clean-audio-power-from-laptop-bricks/

I discovered that adding a single 1N4004 diode to a Schmitt trigger RC oscillator increases edge jitter by 15x, turning a simple 4-component circuit into a cryptographic-quality hardware RNG for microcontrollers.

I've done (What I think is) a pretty comprehensive write up of the project here:

https://siliconjunction.top/2025/12/04/practical-hardware-entropy-for-arduino-projects/