View Full Version : help read Back EMF of DC motor
jetpr
- 21st January 2008, 02:52
Hello if son one don this ..
I need to read Back EMF of DC motor
Darrel Taylor
- 21st January 2008, 04:27
I would probably use an oscilloscope.
Or do you mean, have the PIC read it?
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jetpr
- 21st January 2008, 04:49
yes read with the pic
Darrel Taylor
- 21st January 2008, 05:11
yes read with the pic
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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jetpr
- 21st January 2008, 05:42
my problem is
I needed to know when the motor begins to rotate
Darrel Taylor
- 21st January 2008, 07:55
I - I - I don't have a clue.
I thought it was a different problem. Sorry.
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Acetronics2
- 21st January 2008, 08:44
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
jetpr
- 22nd January 2008, 00:38
thanks for all the help..
Angus Anderson
- 22nd January 2008, 09:16
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
victorf57
- 23rd January 2008, 01:05
Take a look here .
http://www.romanblack.com/encoder.htm
hope it helps
Victor
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