I used to repair EEG systems and we had about a dozen "noisy" units. The boards ...

		neurotech1 on July 27, 2015 \| parent \| context \| favorite \| on: Ask HN: What's the hardest problem you've ever sol... I used to repair EEG systems and we had about a dozen "noisy" units. The boards all tested fine, but were noisy when hooked up to measure brainwaves. It turned out people were running the SLA battery completely flat repeatedly, and subtly "wearing out" the battery.