electromagnetic field sensor

Thread Starter

phill

Joined May 9, 2009
5
for a college project, i need to design and build a "car" which will follow an electromagnetic field eminating from a wire. The wire will be supplied with 20kHz, can any body suggest a suitible sensor to detect this field, at the moment i'm thinking some coils of wire!

thanks
 

mik3

Joined Feb 4, 2008
4,846
for a college project, i need to design and build a "car" which will follow an electromagnetic field eminating from a wire. The wire will be supplied with 20kHz, can any body suggest a suitible sensor to detect this field, at the moment i'm thinking some coils of wire!

thanks
Coils work very well for this case. I have personal experience because my team at my university built one of this with inductive guidance.

Have a look at my blog to see it.
 

Thread Starter

phill

Joined May 9, 2009
5
the video looks very impressive! did you use any formulea to calculate the corect size/values for the coils? Im planning to feed the sensor signal in to an ADC of a micro. What sort of conditioning did you have to do? i'm not after specifics, just generalaties to point me in the right dirrection.

Thanks!
 

mik3

Joined Feb 4, 2008
4,846
They told us to use a 330uH coil but the the current's frequency was 10 kHz. It should work with 20 kHz too.

I suggest you to use an amplifier to amplify the inductors signal and then feed it into a band pass filter as to pass only the 20 kHz signal and reject noise. Also, use a pot on the amplifier as to be able to adjust its gain, it really helps.
 

mik3

Joined Feb 4, 2008
4,846
What is more, I recommend you using more than two sensors as to be able to detect when the car losses the track easily. I used two sensors and I had to sacrifice between steering accuracy and lost track detection. Finally, I didn't use lost track detection and achieved a very accurate steering.
 
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