I don't have 1nF cap, but I have tried 100nF, see no significant improvement, should I get some 1nF caps and try it?In addition to the cap across the motor it is often good to add a pair from each motor lead to the frame of the motor. What you are seeing is brush noise.
I did the measurement as you suggested, and I still see the noise, so how can I measure it correctly?I suppose it could be a measurement problem. Try hooking your ground lead to ground and then scoping ground. If you still see the noise it is a problem with your scope measurement.
Yes, I did that, still see the hairy noise.Make sure you use a regular scope probe with a short ground clip. It might help to have the motor case tied to earth ground.
I have borrowed a set of Tektronix probes from my tutor, still very noisey. Before I was using an original Rigol probes.Just a guess but worth checking out if you can borrow some probes from elsewhere.
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I am using a Arduino Uno board, I think it should have a 100nF close to the chip already.@ bug13
Re your schematic in post 23. I do not see a 100nF cap between the Arduino supply and ground. It is important and should be as close to the chip as physically possible.
Try using an optocoupler between control circuit (Arduino board) and power motor (H bridge). After you attach the optocoupler, mounted, between the power GND and GND Arduino board, one capacitor ~1nF - 1kV.
After doing the above changes, then use galvanically isolated power supply. Ideal would be to use two power supplies but you can use a single source of 9Vdc with the condition: after doing the changes that I have told you, then properly decoupled power Arduino boards through a LC filter consisting of a capacitor of 100nF and a series of 10 ... 100uH inductor.
Thanks for your reply, I will keep those in mind in my next prototype, my little robot works ok now, I will keep it as it it for this one....If you have any single wire going anywhere by itself, you're doing it wrong....
Oh I don't know that, what is the best material for shielding? and what can I use from home if I don't have some suitable shielding material?Shielding, especially aluminum, does almost nothing to magnetic fields.
If you ever really need to shield a magnetic field, one of the best materials is called Mu Metal.<snipped>
Oh I don't know that, what is the best material for shielding? and what can I use from home if I don't have some suitable shielding material?Shielding, especially aluminum, does almost nothing to magnetic fields.
by Jake Hertz
by Aaron Carman
by Jake Hertz
by Jake Hertz