1) Personally I check the Zero/calibration of the tool at every sensible opportunity, that is not just the amps clamp but the DVOM , scope etc. etc. I am always looking to check the tool is giving me sensible numbers. Both the scope and the DVOM get flashed to NBV regularly as a quick and dirty check that everything is OK.
I always zero the DVOM/leads before carrying out resistance checks; especially if the expected value is of a low Ohms figure.
Similarly with the amp clamp they are all subject to temperature fluctuation and battery performance which can also be temperature related. Having said that it does depend on how minutely accurate you need the reading to be.
Call me anally retentive if you like (and many have!) but I prefer to use what I understand as best practice at all times. So yes; for the sake of pushing a button and glancing at the screen I would check it whenever you swap scales or any time when it has been idle for a while. Notwithstanding of course the initial set-up when you first plug it in.
2) There are a number of schools of thought on signal noise. My personal preference is to leave it there in the initial capture as signal noise can be a significant factor in the circuits/components operation. You can always tidy the trace up afterwards. That way you will not miss something that may be important to your diagnosis.
3) As above I do not worry too much about noise but if it is bugging you them tinfoil wrapped around the remaining open section of the loom with a jumper wire back to a good ground will help.
A bit of roofers lead sheet can be a useful signal insulator but keep it contained in a plastic bag or similar because the residue is poisonous and eating your sandwiches after handling it without protection/washing is very bad for your health.
As I said just my opinion and I am sure other will have other advise as well.
Have a good day,
Dave Hill wrote:You can call me anally retentive too, because I am constantly zeroing my amps clamps & not just the Pico low amps clamps either. They all tend to drift after a while & in my experience the Pico units are quite sensitive to external magnetic influences, in particular the magnetic influence that the Earth creates & that is one hell of a magnet!
Try observing a low amps waveform, whilst you wave your amps clamp around like Yoda with a light sabre (don't bother with the sound effect, folks will just think you are just weird ) & you will see the signal wandering all over the place. This is not a fault, it is just the normal effect of the earth's magnetism, so try to zero the clamp, in the same orientation that you are about to take your measurement.
As Kev mentioned, don't be obsessed with noise. Often it can be useful, as it can display events that are occurring on neighbouring circuits, that would otherwise be missed.
Zero often is the best practice in my opinion.
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