Which form of PCB design pattern is better for magnetic field?

I was wondering which form of PCB design patterns, detects mall DC motor running over it better - (change of magnetic field)?
And one stupid question: Can I connect it directly to micros adc with just a voltage protection circuit, if so how accurate can it be?
Well I wanted to detect just if it is rotating or not, but is it possible to detect speed, anything?
will paralleling cap help, or should I be looking into making RC?

Re: Magnetic Field

I was wondering which form of PCB design patterns, detects mall DC motor running over it better - (change of magnetic field)?

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I'm a little rusty in Electromagnetics but as far as I recall, round patterns are better but slightly. The practical results will be similar.You should use the shape that is easier to implement in PCB, IMHO.

Can I connect it directly to micros adc with just a voltage protection circuit, if so how accurate can it be?

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No you cannot. The voltage variations will be around a few milivolts. A microcontroller's ADC usually has 10 bits resolution which does not have enough accuracy to sample the signal directly.

You must amplify the signal first, with an opamp. If you do that you must filter power supply noise with capacitors to avoid interference with your signal.

Well I wanted to detect just if it is rotating or not, but is it possible to detect speed, anything?

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Yes, I think it's possible but it is hard. At every half-turn, the current inside the DC-motor changes direction. You might be able to detect the current's electromagnetic field spike. However you will also be detecting the permanent magnets field which can make it harder to distinguish magnet field from current field.

will paralleling cap help, or should I be looking into making RC?

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I don't understand what you meant with this sentence.

Re: Magnetic Field

I meant for a simple filter, for better ADC reading <Nothing Important>

Re: Magnetic Field

How about connecting to micros Analogue Comparator Input?

Magnetic Field

Hi Ama,
You should connect it so & so to the comparator input, but you must have amplifying, them its to assume that your signal will be in mV range, the comp need surly min 100mV or better at 1V input signal(I dont know what is the minimal reference voltage)...
Greetings!
K.