3 ms·
50hz is pretty easy to knock our with a simple RC low pass filter. That should make a difference but it will probably attenuate the signal so you will need an i
by kryten 13y ago
50hz is pretty easy to knock our with a simple RC low pass filter. That should make a difference but it will probably attenuate the signal so you will need an instrumentation amp.
2 hours later... Ahh commercial grade design and massive BOM.
Great work at keeping it simple :)
- xchip 13y agoThanks! I am using an instrumentation amp indeed. As for the 50hz, I think I'm getting that noise just because my laptop is not grounded properly, no biggie
- kryten 13y agoProbably right. Be careful! I had a Chinese clone Lenovo charger a while ago. There was 50v floating AC on the chassis when supposedly open circuit (!). Zapped myself on any metal part I touched. Fake one was dismantled for study and appeared to be missing most of the components. Tracing the circuit found a 1k resistor between live/hot and the ring on the PSU connector (laptop chassis DC ground). Turns out I was basically turning it into a voltage divider by touching it and was a the mercy of my quite high skin resistance :) Replaced with a genuine Lenovo one immediately resulting in no random minor electrocutions!