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General Discussions => The Chamber => Topic started by: miszt on January 15, 2016, 05:37:15 AM

Title: ATMega based LCRs
Post by: miszt on January 15, 2016, 05:37:15 AM
has anyone tried these cheap ATMega based LCRs, I cant find much info on how accurate they actually are?

they are based on an open source project which seems to have quite allot of support, although the ones available to buy online are clones of apparently variable quality
Title: Re: ATMega based LCRs
Post by: peterc on January 15, 2016, 08:40:43 AM
I have 2 and I use them regularly.

At first I was a bit suspicious and used to confirm my readings with a Fluke meter, but now I dont worry.

Mine have a transistor tester in as well which is nice.

Peter
Title: Re: ATMega based LCRs
Post by: miszt on January 15, 2016, 08:55:08 AM
mine arrived this morning, and so far i'm pretty impressed, none of the components I've tested came outside of their stated range; and its great being able to stick a transistor in and be told instantly what it is, without having to strain to read the print and then look it up

one thing I wondered about was with capacitors and drift; i'm trying to match ones which are labelled 10% tolerance, and according to the LCR, I've managed to find pairs that are within 0.5% of each other for about 2/3's of the capacitors I was testing, all the rest are in 1% pairs - if the readings are accurate, then i'm very impressed (and happy lol)... i guess i'll find out if I have a wonky stereo field when my PQD2 is finished

(going to test all the pairs again a few times before I accept the readings i think)
Title: Re: ATMega based LCRs
Post by: miszt on January 16, 2016, 05:50:13 AM
spent the morning double checking all the capacitor pairs, got almost identical readings to yesterday; the only noticeable difference comes when testing a capacitor twice, without shorting it before testing the second time - and then the difference has so far still only been 0.1%-0.2%

either these things are unbelievably accurate, or they are reliably inaccurate lol either way the best £10 I've spent in a long while :)
Title: Re: ATMega based LCRs
Post by: gyraf on January 16, 2016, 06:30:26 AM
Agreed. I built one of these last week - http://www.banggood.com/DIY-Meter-Tester-Kit-For-Capacitance-ESR-Inductance-Resistor-NPN-PNP-p-929603.html - and I'm amazed how usable it is for the price...

The only half-weak spot is inductor measurement (this is stated in the manual) which is a bit off, but still VERY usable for relative measures.

Jakob E.
Title: Re: ATMega based LCRs
Post by: miszt on January 16, 2016, 08:27:57 AM
Agreed. I built one of these last week - http://www.banggood.com/DIY-Meter-Tester-Kit-For-Capacitance-ESR-Inductance-Resistor-NPN-PNP-p-929603.html - and I'm amazed how usable it is for the price...

The only half-weak spot is inductor measurement (this is stated in the manual) which is a bit off, but still VERY usable for relative measures.

Jakob E.

had a quick read through, the only ref I can find to inaccurate inductance readings are with <2.1K resistors; any idea what the accuracy is for inductor measurements? cant find anything online yet
Title: Re: ATMega based LCRs
Post by: miszt on January 27, 2016, 04:21:28 AM
Spent the week matching resistors, and discovered my unit over calculates values consistently; I only realized when I checked some 0.1% 9.09K resistors, they read as 9.13K, all of them
Title: Re: ATMega based LCRs
Post by: gyraf on January 27, 2016, 07:51:37 AM
Did you do the initial calibration correctly?

Schematic here - http://elecfreaks.com/estore/download/EF06128-LCR-1602tester.pdf - I guess the precision is down to ratio of the 680R/470K resistors (although I'm not sure about this).

References:
http://www.eevblog.com/forum/testgear/$20-lcr-esr-transistor-checker-project/ (http://www.eevblog.com/forum/testgear/$20-lcr-esr-transistor-checker-project/)

http://translate.google.ca/translate?sl=auto&tl=en&js=n&prev=_t&hl=en&ie=UTF-8&eotf=1&u=http%3A%2F%2Fwww.mikrocontroller.net%2Farticles%2FAVR-Transistortester

Jakob E.
Title: Re: ATMega based LCRs
Post by: miszt on January 27, 2016, 10:59:34 AM
I've got the ready made Chinese one, I've read that they can be calibrated but not reliably...i might get the official GPL kit and build it at some point
Title: Re: ATMega based LCRs
Post by: gyraf on January 28, 2016, 03:51:09 AM
On my very-cheap kit (from Banggood, above) I get a reading of 10.03 KOhm for a resistor that measures 9.963 KOhm on my calibrated Fluke45.

That's a deviation of 0.6%

which is quite good considering the kit's $11.5 price tag...

Jakob E.
Title: Re: ATMega based LCRs
Post by: miszt on January 28, 2016, 10:23:45 AM
It seems that the measurements are at least consistent, ie I don't get a different reading for the same resistor at different times
Title: Re: ATMega based LCRs
Post by: Cjuried on March 05, 2016, 07:55:42 PM
Wow. Not bad for under $15. I can deal with +-0.6% for on-the-fly measurements.

On my very-cheap kit (from Banggood, above) I get a reading of 10.03 KOhm for a resistor that measures 9.963 KOhm on my calibrated Fluke45.

That's a deviation of 0.6%

which is quite good considering the kit's $11.5 price tag...

Jakob E.
Title: Re: ATMega based LCRs
Post by: Whoops on May 04, 2017, 09:43:59 PM
I got this one,
Portable MK328 LCR ESR Tester transistor inductance capacitance resistance meter

http://www.ebay.co.uk/itm/Portable-MK328-LCR-ESR-Tester-transistor-inductance-capacitance-resistance-meter-/171927184554?hash=item2807a8a4aa:g:MdoAAOSwk0pVgETb


Let me tell you I'm really impressed, for the price it's the best measuring tool you can have.
I really recommend this to everyone.

Imagine how much electronic engineers would pay for a unit with these capabilities in the 70s....
Title: Re: ATMega based LCRs
Post by: ungifted on May 05, 2017, 04:50:21 PM
I've got various types - L3-L4, M328 (latest, with generator and encoder). Really good tester for transistor testing etc, but must have one of the latest firmware - 1.11k-1.12k
https://www.mikrocontroller.net/articles/AVR-Transistortester
Purchased it for testing germanium transistors: i will compare it with DCA55/75, rg keen and small bear jigs.
Title: Re: ATMega based LCRs
Post by: Whoops on May 05, 2017, 08:41:13 PM
I've got various types - L3-L4, M328 (latest, with generator and encoder). Really good tester for transistor testing etc, but must have one of the latest firmware - 1.11k-1.12k

I have to check with firmware came with my unit.

In case I have an old firmware is it possible to update it?

thanks
Title: Re: ATMega based LCRs
Post by: ungifted on May 06, 2017, 06:01:50 PM
Yes, it's possible to upgrade firmware (usb AVR programmer needed). Here is the link
https://yadi.sk/d/yW8xa5NJgUo5z/Mk-328/Firmware

There is a lot of info over www, incl youtube movies describing how to upgrade your transistor tester.
Title: Re: ATMega based LCRs
Post by: Whoops on May 07, 2017, 10:04:09 PM
Thanks, going to check that
Title: Re: ATMega based LCRs
Post by: squarewave on May 18, 2017, 02:00:12 PM
Purchased it for testing germanium transistors: i will compare it with DCA55/75, rg keen and small bear jigs.
Can these really measure Germanium transistors / diodes accurately? One of these would be great if they really properly report leakage, gain and diode drop of a Germanium transistor.
Title: Re: ATMega based LCRs
Post by: ungifted on May 18, 2017, 02:39:25 PM
Please take a look at my post at diydtompboxes, I've compared all I've got:
http://www.diystompboxes.com/smfforum/index.php?topic=117061.msg1092755#msg1092755
Title: Re: ATMega based LCRs
Post by: cyrano on May 18, 2017, 05:03:12 PM
Very interesting. Not only the meters, but also the Russian germanium transistors. Thanks!
Title: Re: ATMega based LCRs
Post by: Whoops on May 18, 2017, 08:25:03 PM
Very nice Link and tests.

Thank you Ungifted
Title: Re: ATMega based LCRs
Post by: ungifted on May 19, 2017, 03:27:59 AM
Thank you for your feedbacks and support!
Title: Re: ATMega based LCRs
Post by: Whoops on May 24, 2017, 04:34:47 PM
Hi Ungifted I just checked my MK-328 tester and it already came with the firmware V1.12K

Do you know if this meter takes into account (subtracts) Leakage from the HFE measurement when measuring HFE of germanium transistors?



Title: Re: ATMega based LCRs
Post by: ruffrecords on June 10, 2017, 04:37:23 PM
Can anyone recommend a good one of these that will test JFETs? The one I have just identifies them as a pair of diodes and gives the forward voltage drop.

Cheers

Ian
Title: Re: ATMega based LCRs
Post by: ungifted on June 10, 2017, 07:27:38 PM
Whoops Yes, it takes into account leakage when measuring germanium transistors, please check 1.12k datasheet
https://github.com/svn2github/transistortester/tree/master/Doku/tags/english/ttester_eng112k.pdf
ruffrecords
At least MK328 must measure JFETS, not so in detail as DCA75 but it it must identify them correctly. I saw jfets as a diode junction with fake J201s or SK170s when their gain is too low or possibly other reasons. BTW even mk328 with 1.12k doesn't show Vgs (off) though it must (see docs). Only Vg (on) shown.
Please note that every transistor tester from China with 1.12k must identify jfets. But stock firmware of T3-T4 as instance identify them as BJT.
Title: Re: ATMega based LCRs
Post by: squarewave on July 01, 2017, 10:25:21 PM
I just tried the one pictured here:

http://www.instructables.com/id/AVR-Transistor-Tester/

and it was a total fail for measuring JFETs. I manually measured Idss of a J201 at 390uA and the tester reported 220uA.

I tried to calibrate but it didn't make any difference.
Title: Re: ATMega based LCRs
Post by: Whoops on July 02, 2017, 03:34:21 PM
Wow. Not bad for under $15. I can deal with +-0.6% for on-the-fly measurements.

yes, probably not bad even if it cost $150

lololol