Inductance meter

[dotneck335]

Looking for a meter to measure inductance; specifically 130uH. I already have a nice Fluke digital meter for measuring voltage, resistance, and current; and I have a good B&K capacitance meter. But I need an inductance meter that will measure down in the uH range---don't need the other measurements and don't want to spend a lot of money. Any suggestions?

 

[CG]

https://www.amazon.com/5000-Handheld-LCR-Meter-accessories/dp/B00S298KJO

Note: You can often get these for less elsewhere.

There's other newer gadgets out there now, too, but I have no experience with those.

 

[trobbins]

Is the measurement to be made with just a small ac signal, or is the inductor operating with high signal levels and with a DC component?

 

[Mark Johnson]

I own and use six different inductance meters, at price points from USD20 to USD700. The one I use and rely upon the most, is a brand called "DER-EE" and a model called DE5000. It's sold lots of places but the best value for USA buyers is eBay. Get one that is bundled with ALL the accessories, especially the tweezer option. You won't be disappointed.

 

[Mello4]

.... The one I use and rely upon the most, is a brand called "DER-EE" and a model called DE5000.....

That is the DE5000 that was posted in the link above. I have one & it works well. It is physically larger than it appears in the picture.

 

[dotneck335]

Is the measurement to be made with just a small ac signal, or is the inductor operating with high signal levels and with a DC component?

It is for a coil operating in a sensor circuit, driven by an oscillator---- ~ 10v p-p @ 833 KHz, no DC.

 

[trobbins]

Is it air-core?
One option is to drive the inductor with your intended oscillator at the intended signal voltage, and use a series RC to identify resonance. You may already have test equipment that can accurately measure frequency and capacitance.

 

[dotneck335]

No, its with a P14x8 pot core. You have a good point that I could just determine it from its resonant point with a known-value capacitor.

 

[Mark Johnson]

If you happen to have a Quasimodo or Cheapomodo test jig, they measure inductance quite readily. Apply stimulus, measure ringing frequency fR, insert fR and Cx into parallel LC resonance formula ---> shazam, out pops L.

 

[jackinnj]

Got an am radio? 130uH will resonate at 1,040kHz midway through a 365pf variable capacitor. Make a one transistor oscillator with the inductor and variable cap, set the a.m. radio to say 1MHz, sweep the variable cap until you get a beat, measure the capacitance and the inductance falls out from the math.

Everybody should have a voltage network analyzer. The "Steber" Impedance Measurement Set used a sound card and a quad op-amp -- unfortunately, the software was circa 2005 but there are variants on the web: ZRLC

If you would like the original QEX article PM me as it's now behind a paywall.

 

[Mark Johnson]

Or buy a DER-EE DE5000 for $118 and let someone else do the parts purchasing, board assembly, debugging, and (most annoying of all jobs) calibration.

 

[jackinnj]

Or buy a DER-EE DE5000 for $118 and let someone else do the parts purchasing, board assembly, debugging, and (most annoying of all jobs) calibration.

Or you can get one of these for ~$10 -- very, very handy.

 

[Mark Johnson]

Believe it or not, somebody is still building and selling brand new grid dip meters. I happen to know this because I bought one last September. The device is "MFJ-201" (sometimes listed without the hyphen) and I paid just under $200 for mine.

link

 

[Mello4]

Or you can get one of these for ~$10 -- very, very handy.

With the 6AF4A tube....

Eico model 710 grid dip meter, instruction manual: Eico: eico model 710 grid dip meter : Free Download, Borrow, and Streaming : Internet Archive

 

[dotneck335]

I'm wondering if one of these would get me by. My measurement doesn't have to be super-accurate; I think 20% ball park would be good enough.
LC-100A LCD Capacitance inductance meter LC Meter 1pF-100mF 1uH-100H - Newegg.com

 

[1audio]

It looks quite good actually. I'm tempted even though I have several high performance meters simply to save the space.

 

[Mark Johnson]

Thanks for the pointer! I decided to buy an LC100A on eBay, where several sellers offer it. The one I happened to choose was (here)

 

[dotneck335]

I also placed an order with that seller. Be interesting to see how well the LC100A measures. I figure I can check its accuracy by using my HP AC voltmeter, HP oscillator, a capacitor with known value from my B&K cap meter, and some mathematics.

 

[JohnPM]

If you use REW you could also use its component model analysis of impedance measurements.

 

[jackinnj]

If you use REW you could also use its component model analysis of impedance measurements.

And while you're at it, you can use REW to characterize all the components like magnetizing and leakage inductance of transformers, interwinding capacitance etc.