Custom hardware


I try to build an energy monitor and this works fine. The only issue is when occur noice in the AC line, the display go crazy, and I can stop it.

Any idea how I can isolate the noice from the 9V AC Transformer to the circuit?

Robert Wall's picture

Re: Custom hardware

That is surely a problem with your supply, not with the measurement of it?

If you have noise spikes, it is far better to trace the source and apply suppression there than to try to filter the noise out elsewhere. If the noise is not being generated by something you own, you might find that there are regulations that limit the amount of noise that can be injected onto the public electricity supply, and your electricity supplier might be able to help.

Alternatively, you could introduce a low pass filter, for safety's sake on the secondary side (unless you buy an approved noise suppressor that works at mains voltage), but a filter will inevitably introduce a phase shift that will mean you must recalibrate.

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