My boost converter makes little buzzing noises according to how much of the OLED is being used. The boost converter takes 9v down to 3.3 and powers both the OLED and the 74lvc245 logic converter. I’m thinking maybe I could put a 100nf capacitor between vcc and gnd to filter out the noise?
Sorry, I cannot help with your question but are curious to know how long a 9V battery would last with this large screen?
A lot longer than you’d think. About 8 hours, from what I remember calculating
Yeah the boost converter on those displays have a decent coil whine to them. Not sure what specifically causes it, but it would be cool to know!
So nothing to worry about I take it?
I think @Nateo87 is talking about a separate converter that reduces the 9V battery voltage down to 3.3V (which would be a buck converter, not a boost converter).
A capacitor might help somewhat, if the buzzing is due to rapid changes in current draw, not just relatively slow variations in DC current. It would likely have to be much higher than 100nf, though.
The noise you hear is caused by the switching current running through the inductor coil of your DC converter or the one on the OLED display or both and is typically known as coil whine Usually you can say the higher the load (current) the more noise. Adding hot glue to the inductor(s) sometimes help to reduce the noise.
It’s the OLED display that requires most of the power. It’s boosting your 3.3V up to ~14V to drive the OLED panel. To reduce losses and hopefully some noise. You could try to increase your DC converters output to let’s say 3.6V (The OLEDs SSD1309 controller max voltage rating is 4V according to the datasheet.).
Certain capacitors can whine or buzz at audio frequencies, as well.
Oh he said boost, but you are right, either way those cheap modules are noisy.
If it really bothers you you could replace the coil with a potted one to dampen the audible harmonic or just remove the onboard converter and supply the oled bias voltage externally from a properly designed boost converter with the switching frequency and subsequent harmonics well above the audible range.