$18 LCR Meter

[Silver Dollar]

I bought this LCR meter fpr $10.29 + $7.99 shipping and it came in today.

It works great for measuring the coil inductance (but only 2 digits for PI)

I'm not sure if it is still available? I have a link but couldn't find it by searching

http://www.ebay.com/itm/300418629699...84.m1439.l2649

[Mega B]

Have seen the same meters on on the UK Ebay site and was wondering if they are any good as i am just about to buy one,not sure what you mean by the 2 digits but the coilos that i am planning on using it on are for a Pulse machine,you can tell that i am just a novice at this game

[Silver Dollar]

Well it seems to work great! The numbers are repeatable. But it only has 2 digits in the uh range
so 540 uh reads .54. That's still fine by me as the VLF coils in the mh range read with enough
resolution. I'd buy it again!

[Mega B]

Many thanks for the update on the LCR meter,i will buy the exact same item this afternoon.

[bernte_one]

the 4070L from china is crap a own it too before i spend me a peaktech 2010 made in germany direct from factory around 20€
i got better results all L measurements with 4070L i made before were wrong

[WM6]

the 4070L from china is crap a own it too before i spend me a peaktech 2010 made in germany direct from factory around 20€
i got better results all L measurements with 4070L i made before were wrong

Or vice versa.

[sinclairuser]

they are like all mass produced instruments, some work spot on some not so, i have 3 identical ones that look a lot like the pic, one is a philex original, the other 2 are clones while one clone is actually more accurate than the philex, the other is worse it seems to be somewhat of a lottery.
as a stand alone tool to build coils they are a bit naff, but in conjunction with a scope they are ok, its more important that they give stable readings than anything else, even with expensive models you should still short the probes and take base readings.

[WM6]

they are like all mass produced instruments, some work spot on some not so, i have 3 identical ones that look a lot like the pic, one is a philex original, the other 2 are clones while one clone is actually more accurate than the philex, the other is worse it seems to be somewhat of a lottery.
as a stand alone tool to build coils they are a bit naff, but in conjunction with a scope they are ok, its more important that they give stable readings than anything else, even with expensive models you should still short the probes and take base readings.

Sometimes is better to use cheap L-meter with proper working frequency (for VLF/IB measurement say of about 5kHz) than high precise L-meter with improper working frequency (say 500kHz or more of measurement working frequency). The difference in results is significant, but this does not mean that results from high precise 500kHz L-meter are more correct for our VLF/IB coil needs.

Here is better to ask what should be proper working frequency of L-meter for PI coil measurement.

[Bob_T]

WM6, I also wondered about the effect of frequency on inductance measurement too. I bought a DER EE DE-5000 meter from ebay. It has a selection of measurement frequencies of 100Hz, 120Hz, 1kHz, 10kHz and 100kHz. The measured inductance doesn't very much more than 1uH from 100Hz to 100kHz. I don't know what the effect of using one of the RF frequency meters that measure at 500kHz might be. I spent about $150 USD on my meter including shipping from Japan (meter is made in Taiwan, and surprisingly it came with a 9 volt battery installed that was made in the USA) and I'm very happy with it, although I now think that a $20 meter might give the same results for the frequencies we're interested in. The bad news is that my first coil that should have an inductance of about 300uH according to the calculations, measures at 250uH. So far it's unshielded and I'm going to wrap the shielding on and see what effect is has on the inductance.

Thank you for bringing up the point of possible change in measured inductance with frequency.

Bob

Sometimes is better to use cheap L-meter with proper working frequency (for VLF/IB measurement say of about 5kHz) than high precise L-meter with improper working frequency (say 500kHz or more of measurement working frequency). The difference in results is significant, but this does not mean that results from high precise 500kHz L-meter are more correct for our VLF/IB coil needs.

Here is better to ask what should be proper working frequency of L-meter for PI coil measurement.

[Bob_T]

As a follow up to the previous post, I wrapped the coil with shielding tape and measured the inductance again. There wasn't a significant change at 1k or 10k Hz but at 100k Hz the measured inductance dropped by about 20%. I don't understand why, but the lesson for me is that inductance measurements taken at frequencies much higher than 10kHz with a shielded coil are probably suspect for metal detector coil purposes.

Bob

[WM6]

There are different applied method to measure inductance in L-meters.

Sometimes, especially in MCU controlled units with single working frequency some correction factor is added to calculating code for different inductance range.
Sometimes frequency is adapted to pre-measured inductance value and recalculated.

There was never pure inductance with our coil.
We can count at parasitic capacitance's and resistances and stray coupling between all of them, which cause distortion in measurement.

With added shielding all those stray couplings are magnified.
Usually not big problem with bigger inductance's at low working frequency, but if we change L-meter to higher working frequency, such parasitic and stray coupling become important.

Nevertheless, in cases when we measure original factory coils, using cheap L-meter, to manufacture our own coils, we can count on exact and reliable results. We only need to take measurements at same working temperature to minimize temperature drift in results.

What, if we got coil data from web and we don't know what sort of L-meter was used to get those coil data? In this case will be of little importance, if we use high precision instrument, if data was taken by cheap one, and vice versa. For our amateur needs, practically all available instruments in $40 class and above more than satisfied. Correct handmade too. More important are coil building knowledge and constructor experience.

And yes, it is usually more correct, for our VLF needs, to use cheap L-meter with single working frequency at 5kHz, than high precise instrument with single working frequency at 500kHz.