Suitable alternative to the AADE LC meter

[bd139]

I'm on the market for an LC meter. The one I was after has been discontinued as the poor chap who sold it is now silent key.

I don't want to fish out for an expensive LCR meter and need something with reasonable resolution for toroid winding and checking variable and fixed capacitors. Currently I'm using a resonant circuit with some 1% mica caps and signal generator, scope and counter and it's accurate but it's a pain in the butt.

I've got a cheapy chinese "transistor tester" but it's shit. It can read a different value every time I run it and it is more than 10% out measuring a decent quality 1% mica cap.

Any suggestions / homebrew versions / anything I can look at in this space appreciated. I can program AVR and PIC devices and modify code if needed.

I don't need it to be able to fluff around with any components other than inductors and capacitors for ref.

[CJay]

You might want to calibrate that cheapy one, they're pretty good in my experience though they struggle with caps under 10-15pF and low value inductors.

There's a few designs on the web which are similar in principle to the AADE ones, they work on the same principle at least. There were some PIC based ones ISTR...

[bd139]

Ok will have a look around - thanks for the pointers. A quick Google points to this article ( http://kripton2035.free.fr/LCR%20meters/lcr-marc.html ) which I happen to have all the bits lying around for.

I'm trying to measure quite low inductance (hundreds of nH to 20uH max) which this one appears not to be particularly happy with. Plus it won't calibrate sensibly. If I cal with the supposed 220pF capacitor (I've got a 1% silver mica here), when I stick a 100pF one in, it reads 145pF. If I stick the 220pF one back in, it reads 300pF. It should in theory calibrate out the fixture capacitance but nope, shitty software I suspect.

If I build one with PIC source at least I can fix it so it works properly

[Z80]

As you are in the UK, I'll blow the trumpet for this company:
http://www.peakelec.co.uk/acatalog/jz_instruments.html
I have a couple of their products and they are pretty good.  When you start getting down to low values like 5pF caps then it is often very easy to get swamped by parasitics even after doing a zero cal.

[w2aew]

You might want to calibrate that cheapy one, they're pretty good in my experience though they struggle with caps under 10-15pF and low value inductors.

There's a few designs on the web which are similar in principle to the AADE ones, they work on the same principle at least. There were some PIC based ones ISTR...

I think this is based on the same principle as the AADE unit.  Seems work pretty well on low values.
http://electronics-diy.com/product_details.php?pid=500&name=Special%20Edition%20Accurate%20LC%20Meter%20Kit

[GrahamC]

I have had an AADE LC meter for many years and it has served me well. As you note, it is no longer available except as used.

I also have a couple of the inexpensive Asian sourced AVR based LCR meters, they are ok but leave me wanting. They do generally work well for quick and easy part id'ing which the like of the AADE does not.

After much fussing and reading and viewing youtube videos plus a nice review by Dave of EEVBLOG and for which you will find many postings on this forum, I bought a DER DE-5000 LCR meter.  It does everything and as well as and better too than the AADE does. The AADE is a simple and dated design but did what it does quite well. The DER DE-5000 is a more modern integrated design with many more features AND for a bit less money than the AADE sold for in it's final years of availability.

There is something to get said about building your own and I do so frequently. But there is something to be said for an off the shelf solution as well.

cheers,

[bd139]

Might be buying an atlas LCR45 yet...

Edit: although I’ve wound about 10 toroids this year so that’s about £9 a torpid so not sure it is justifiable for this. I have a UT61E which is ok for capacitance. Saw a shitty Heathkit GDO go for £166 yesterday though.

[CJay]

You might want to calibrate that cheapy one, they're pretty good in my experience though they struggle with caps under 10-15pF and low value inductors.

There's a few designs on the web which are similar in principle to the AADE ones, they work on the same principle at least. There were some PIC based ones ISTR...

I think this is based on the same principle as the AADE unit.  Seems work pretty well on low values.
http://electronics-diy.com/product_details.php?pid=500&name=Special%20Edition%20Accurate%20LC%20Meter%20Kit

And I think this was too but there's firmware available, albeit for the ancient 16F628 or even older 16F84, 

https://sites.google.com/site/vk3bhr/home/lcm1

[bd139]

I’ve got a whole tube of 16f628’s and a working JDM programmer somewhere (assuming I can find a serial port in the house) so this is technically free

[bd139]

For ref, I've scrapped this and am building a little box based on the article that kicked off all these things that plugs into my DG1022's counter and then reads it off via SCPI/LXI (or my dumb counter and a calculator program - haven't decided yet). Will post a thread when complete.

[CJay]

A link to the article would be nice...

G3UUR crystal testing is working nicely BTW, filter passband looks *lovely*...

[bd139]

Thought I put one. Fail!  Here you go: http://www.qsl.net/wm5z/cq199301b.pdf

Parts arrived this morning so will get on with it this week when I get some time.

G3UUR crystal tester looks interesting - will read further into that today

[bd139]

Boring bit aka the box is done. The innards are still winging their way from various places.

This box was done whilst muted on a conference call about ISO 27001.

[GrahamC]

There are other simple alternatives that you may find useful, in particular a sound card based RLC meter,

https://www.eevblog.com/forum/suggestions/poor-man%27s-rlc-meter-software-pc-soundcard/

http://www.sillanumsoft.org/ZRLC.htm

http://wb6dhw.com/RLC_Meter.html

http://www.rcl-meter.strobbe.org/

http://www.daqarta.com/dw_0o0z.htm

use google and search for sound card RLC  or  sound card LCR  or sound card impedance meter and you find a few other examples.

cheers, Graham

[bd139]

Interesting stuff in there. Thanks for the links

[bd139]

Got some time to put some brains in the box. Didn't fancy winding the toroid tonight so the output amp complete and tested:

[orbanp]

The "Secohmmeter" that is available on eBay in kit form uses the same principle/circuit as the AADE and similar LC-meters:
https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2380057.m570.l1313.TR0.TRC0.H0.Xsecohmmeter.TRS0&_nkw=secohmmeter&_sacat=293
It uses the Atmel AT89S52 processor.
The board I have (it looks like there are two versions of the PCB available) has the ISP-port, so one can reprogram the firmware easily, right on the board.
There are a number of minor issues (at least to my mind) that can be corrected.

Peter