Hi,
I've implemented the circuit as shown here: http://openenergymonitor.org/emon/buildingblocks/how-to-build-an-arduino-energy-monitor-measuring-current-only
It works perfectly when my laptop is not connected to the charger. However, as soon as I connect my laptop charger the values go wrong. Is there anyway to prevent this?
P.S.: Newbie at this stuff. :)
Re: Values Disturbed when Laptop is Charging
My best guess is you are picking up radiated magnetic fields from the laptop charger. Move it away.
The next best guess is the charger is putting a lot of electrical noise onto the USB connector (if that is what you're using) or back into your electricity supply. If that is the case, you probably need to get a better charger, or a better power supply for your Arduino, or add some RFI filters.
Until you find out exactly how the interference is getting in, it is very hard to suggest a cure.
Re: Values Disturbed when Laptop is Charging
First of all, thanks for replying. :)
Coming to the problem, as far as the laptop charger radiating magnetic field is concerned, I don't think that would be an issue because the disturbance doesn't occur until the charger is connected to the laptop. So, if I have the charger on, and even near my sensor, it won't affect it until I connect it with the laptop.
As far as the charger putting electrical noise onto the USB connector, I think that is the main issue, since I am using it to supply power to my Arduino. I'm using a Dell Laptop with its original charger so I'm not sure if I could get a better charger than the original.
So I guess, what I need to do is either supply power to Arduino from a different source or add some RFI filters. Could you help me with that, since I'm new to this so I'm not sure how would I be able to do that? For reference, my Mains Voltage is 230V, Frequency 50Hz and Alternative Current (AC).
Re: Values Disturbed when Laptop is Charging
because the disturbance doesn't occur until the charger is connected to the laptop
I'm not sure that's a particularly good test. The SMPS inside the charger will be behaving vastly differently when it's driving a load Vs idle; just notice how much warmer it gets when it's working. If you really want to test that theory, power the Arduino from a different source altogether, and then bring your laptop charger (connected to your running laptop) close to it and see if anything changes.
Re: Values Disturbed when Laptop is Charging
Anecdotally, self-built front ends and Arduino boards have always been more susceptible to noise and interference than the emonTx. The latest emonTx has, I believe, passed the EN 61000-6-3:2007 and EN 61000-6-1:2007 certification. Not that this will help you in your particular case.
Let us know what a separate power supply to the Arduino does for you, and we can take it from there.