help read Back EMF of DC motor

Hello if son one don this ..

I need to read Back EMF of DC motor

I would probably use an oscilloscope.

Or do you mean, have the PIC read it?
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yes read with the pic

Quote:

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Originally Posted by jetpr

yes read with the pic

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Well, I won't say that it can't be done.

But the thing is ... For any normal "dc motor" circuit, you need to "shunt" any "Back EMF" with reverse biased diodes, because the voltage is outside of the operating range of the PIC. And being "outside" of the PIC's range, it can't read it.

I'm sure it's possible to create a Test Circuit to measure the effect, but if you just want to try and read it, because it keeps reseting the program. It would be better to use an oscilliscope.
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my problem is
I needed to know when the motor begins to rotate

I - I - I don't have a clue.

I thought it was a different problem. Sorry.
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Hi,Jetpr

Was a long time ...

Do a search in the Microchip app notes ... this question is covered ( 3 or 4 ANs )

I think there was also a Thread about this subject at RC Groups Forum, DIY section ... "BLDC" keyword could be the one ...

a Happy new year to you.

Alain

thanks for all the help..

Hello Jetpr

Look at Microchip Appnote AN893. Back EMF RPM monitoring is explained in H Bridge DC motor application. Also AN905 which explains Brushed DC motor control fundamentals

Hope this helps

regards


Angus Anderson

Take a look here .
http://www.romanblack.com/encoder.htm
hope it helps
Victor