gEDA-user: buzzing board

[DJ Delorie]

> Does the switching power supply have a transformer?

No, it's a simple buck converter.

> Does the frequency change when you change load?

No, just intensity.

> Is the output noise within the power supply specification?

The switcher's output is pretty clean, about 7 mVpp at 150 kHz.

The OLED uses a +12 LDO; the oled side is pretty dirty (0.5 Vpp) but
adding a huge cap to it (which nearly eliminates the noise) doesn't
change the sound.