# LCR meter

Discussion in 'Electronic Repair' started by D-unit, Nov 6, 2007.

1. ### D-unitGuest

What is an LCR meter?

Thanks,

Don

3. ### Arfa DailyGuest

"L", the mathematical symbol for inductance, "C", the same for capacitance,
"R" the same for resistance, so a meter that measures inductance,
capacitance, and resistance ...

Arfa

4. ### D-unitGuest

VOM other than the "L" and the "C"?

Thanks!!!!!!

Don

5. ### GGuest

No, its rather simple. You can buy better true RMS meters. If
you have the need for the LC meter, then its real handy. I don't understand
why more meters don't have the L, other than the need. If you can measure
C, then it easy to convert to L measurment with the right calculations.

greg

6. ### joeGuest

Hmm, interesting,
I have a Capacitance meter, so how do I check an inductor with it ?

7. ### John BachmanGuest

This seems to be the blind leading the blind.

There is no way to connect an inductor to a capacitor meter, get a
measurement and then calculate the inductance.

If you want to measure resistance then a VOM will do the job. If you
want to measure capacitance then a capacitance meter will do the job.
If you want to measure inductance than an inductance meter (I suppose
that there is such a thing) would do the job.

If you want to measure resistance, inductance and capacitance with one
meter then you need an LCR meter.

See a nice one at www.anatekcorp.com/testequpment/atlaslcr.htm

John

8. ### Arfa DailyGuest

They do come in other combinations as well. My bench portable digital meter
has the standard volts, amps and ohms ranges, as well as L and C, so I guess
that's an LCRVA meter ... !!

One interesting thing that I'd never noticed before. The bank of half a
dozen switch positions which cover the capacitance ranges, are actually
marked "F" ...

Arfa

9. ### CJTGuest

Are the inductance ranges marked "H?"

10. ### Arfa DailyGuest

Ah yes ... I see where you're going ! Indeed they are. "H" for Henries, "F"
for Farads. Each individual range is then marked by its sub multiplier 2n
..... 200n .... 200u ....F

Amazing how 'fixed' you can get in your thinking. I used to have a digital
meter that had a crude frequency counter - as in it only went to a coupla
megs - built into it, and I seem to recall that the frequency ranges on that
were marked "F" also, hence why my poor addled old head immediately thought
"Frequency" rather than "Farads". Thanks for making me think about it again
!

Arfa

11. ### GGuest

Why don't you try it and get back to us. I never tried it. A capicitance
meter has a resistor, oscillator, and voltmeter. An inductance meter
has a resistor, an oscillator, and a voltmeter. I would think it
should work. You do have to generate a conversion graph.

greg

12. ### John BachmanGuest

The difference is that a capacitance meter usually uses a known
constant current source to drive the capacitor under test and monitors
the resulting voltage to calculate the capacitance.

Conversely, an inductance meter uses a known constant voltage source
to drive the inductance under test and monitors the resulting current
to calculate the inductance.

Therefore, your scheme will not work.

John

For the OP,

The proper term for these things is 'LCR bridge'

Googling that shows plenty of examples

14. ### John BachmanGuest

A bridge is one type of LCR meter. The OP originally asked about
meters, which do not have to be bridges.

John

OK, but I would guess by number that most LCR meters worth using (and
probably sold) would work by the bridge method?

<http://www.multimeterwarehouse.com/SM8280.htm>

So something else to look at...