Cheap DMM that does L and C?

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abraxalito

abraxalito

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Joined 2007
For measuring L, its not just the value but the losses over frequency which are important. A cheap DMM will, if it measures L at all (I've never seen one that does) only measure at a single frequency and not measure loss (or Q).

Worth investing in a decent 4-wire LCR bridge IME.
 
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gootee

Member
Joined 2006
fullnet.com/~tomg/index.html
The cheapest (but not actually cheap) somewhat-decent LCR meter that I've seen (as of a year or so ago), which is not a multimeter, is the Tonghui TH2821A. It has a four-wire probe setup and measures L, C, R, and Z, and measures Q for L, C, and R, and DF for C. Frequency is selectable from 100, 120, 1000, and 10000 Hz. It auto-calibrates by asking you to short and open the test clips. Check ebay.com .

Or, you could make or buy a bridge.
 
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macboy

Member
Joined 2003
The two that dudaindc refers to can be built if you are into PIC microcontrollers; just google "PIC microcontroller LC meter", and you will find several similar projects. The accuracy ultimately depends on the accuracy of a precision capacitor that is used as part of the measurement (so probably no better than 1%).

You can buy even cheaper meters on eBay, don't search for DMM, search for "LCR meter". You can get a handheld model as cheap as < $20 US. Carefully consider the measurement range vs. your needs, the accuracy or lack thereof, and the measurement frequency. If you will use your inductors at 100 kHz, there is little point in measuring them at 100 Hz (which happens to be the frequency that many of the cheap ones use).
 
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ChicagoJTW

Member
Joined 2011
The C measurement is generally the limiting factor. If you only want to measure small capacitors, there are a number of inexpensive options. If you want to measure over 25000uF or so, you need to buy a separate LC or capacitance meter and forget about combining all the other DMM functions.
 
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macboy

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Joined 2003
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AudioLapDance

Member
Joined 2003
Thanks everyone for the great replies.

My original reason for wanting a cheap LC meter: I have a bunch of crossover inductors that the stickers have fallen off of and I can remember what value they are.

Yes I know I could set up a test frequency and resistor and measure them but I thought having a cheap general LC meter would be good.

As I don't have a lot of free time anymore (2 year old) I was looking for a ready-to-go-meter rather than a kit.

So I'm looking for something to mostly measure crossover caps and inductors and active filter caps.

Thanks again,
Cheers,
Jeff
 
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AudioLapDance

Member
Joined 2003
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bear

bear

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Joined 2002
bearlabs.com
There are some that are multimeters DMM, that do L,C,R & F...

Alpha made one.
There is another brand too... or more.

They can be found, in the ~60-90$ range.
Perfectly serviceable for getting close to the real value, not half bad actually. Won't replace a precision instrument IF you need one.

I have a precision bridge, but rarely need to use it... I end up using that mostly for precise R measurements... although it will permit external freq source so you can see what the cap (for example) does at some reasonably high frequency...

check ebay, of course...

_-_-bear
 
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