measure DCR with multimeter...

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warpie

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Feb 7, 2009
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I can't find it right know but I think I've read a topic some time ago that was mentioned that measuring the DCR of an inductor with multimeter is not a good idea because you might magnetize it. So, is it risky to measure the resistance on each tap of an eq inductor with my multimeter?

thanks
w.
 
thanks for the help s2udio.

btw, just out of curiosity, what are the symptoms of a magnetized inductor/transformer?
 
To measure resistance the DMM injects a DC current which can magnetize the core. Modern meters keep the current small to aid in-circuit measurements, i.e. they avoid the forward bias of diode junctions. Hence magnetization is much less a problem than it used to be.

What are the symptoms of a magnetized inductor/transformer?

Increased distortion, less low-frequency bandwidth.

Samuel
 
Increased distortion, less low-frequency bandwidth.
thanks Samuel!

Modern meters keep the current small to aid in-circuit measurements, i.e. they avoid the forward bias of diode junctions. Hence magnetization is much less a problem than it used to be.
is it the case for even the $10.00 quality DMMs?
 
There is another gotcha when using SOME digital multimeters to measure transformer DC resistances.
These types of digital multmeters only take the resistance reading periodically for some fraction of second to conserve battery power.
This can cause an inductive "kick" voltage during measurement and give you wild, inconsistent readings.
Some auto-ranging digital multimeters are even worse.
That's one of the reasons I keep a beat-up old Triplett analog meter on my bench.

Cheers.

ZAP
 
zapnspark said:
There is another gotcha when using SOME digital multimeters to measure transformer DC resistances.
These types of digital multmeters only take the resistance reading periodically for some fraction of second to conserve battery power.
This can cause an inductive "kick" voltage during measurement and give you wild, inconsistent readings.
Some auto-ranging digital multimeters are even worse.
That's one of the reasons I keep a beat-up old Triplett analog meter on my bench.

Cheers.

ZAP


Is this also applicable when you measure DCR of a loudspeaker?
 

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