Close
0%
0%

LC100A LC Meter Fix

Turn a cheap LC meter into a highly accurate device!

nqtronixnqtronix
Following
Liked Like project

Just one more thing

To make the experience fit your profile, pick a username and tell us what interests you.

Pick an awesome username
hackaday.io/
Your profile's URL: hackaday.io/username. Max 25 alphanumeric characters.
Pick a few interests
Projects that share your interests
People that share your interests

We found and based on your interests.

Choose more interests.

OK, I'm done! Skip
Similar projects worth following
11.6k views
7 comments
15 followers
View Gallery
The LC100A is a fairly popular and cheap LC meter available on aliexpress and similiar sites. It is advertised as an up to 1% accurate device (depends on range) with a resolution of up to 0.01pF and 0.001uH. Unfortunatly he device I received had errors up to 50% and was thus not usable at all.

Thanks to a comment on aliexpress I found out that the issue was low quality components for the LC resonance circuit, likely the manufacture substituted them because they were cheaper. I think the main issue was that the max frequency was well above the rating of the inductor, so it's effective inductance dropped and threw off the measurements.

I replaced the parts with the best I could find (part names below) and the performance is within spec now. During my research I found a manual and a low-res schematic; I've up-scaled the latter manually and have both files attached below. The pictures are watermarked to prevent the seller from using my pictures.

3_LC100a_schematic_upscale.png

Portable Network Graphics (PNG) - 848.15 kB - 12/21/2020 at 13:24

Preview

4_User-manual-of-LC100A.doc

msword - 181.00 kB - 12/21/2020 at 13:24

Download

5_comment_aliexpress.PNG

Portable Network Graphics (PNG) - 963.97 kB - 12/21/2020 at 13:24

Preview

MURATA_2200R.pdf

Adobe Portable Document Format - 156.24 kB - 12/21/2020 at 13:32

Preview

WIMA_MKP4.pdf

Adobe Portable Document Format - 477.61 kB - 12/21/2020 at 13:32

Preview

View all 6 files

  • 1 × MURATA 22R104C inductor, 100uF 10%, self resonance 7MHz, high Q>90
  • 1 × WIMA MKP4F031003C00JF00 capacitor - PP film, 100nF 5%
  • 1 × WIMA FKP2J011001D00HI00 capacitor - PP film 1nF 2.5%

Enjoy this project?

Share

Discussions

briker.fm2019 wrote 04/04/2022 at 21:16 • point

i have this kits but ic stm broken. can you share firmware for replace new ic stm to me?

  Are you sure? yes | no

nqtronix wrote 05/28/2022 at 20:03 • point

Sorry, I don't have a programmer or the required software to read it, and even if I could, I'm certain it will be locked.

Sorry for the late reply, hackaday.io's notification system is broken and I didn't get an email.

  Are you sure? yes | no

paulandreasen wrote 01/09/2022 at 00:59 • point

Mine was 4-6% off on lo caps, 20-40% off on high caps. After your mod, I get 40-300% off on lo caps, 1-4% on high caps. Duh! Used your exact parts. Replaced caps with Vishay 1%'ers and samo-samo. Any guesses?

  Are you sure? yes | no

nqtronix wrote 05/28/2022 at 19:59 • point

Did you remember to zero before the measurement? This LC meter measures the DUT with an LC oscillator, and I replaced the critical parts with parts which are stable across a wide frequency range. If you have exactly the same parts, I have no idea that the issue could be.

Sorry for the late reply, hackaday.io's notification system is broken and I didn't get an email.

  Are you sure? yes | no

paulandreasen wrote 05/29/2022 at 02:41 • point

Yes, I did zero it out. Weird. I cannot find any problems with the board or wiring, and replaced the parts (I had ordered a few of each - cheaper) I got a friend who works on Vandenberg Space Force Base nearby, in their PMEL shop, to check all he components. All were within a couple % of ratings. Just my luck I guess. Good thing I am getting too old to do much now!

Thanks for the reply tho!

  Are you sure? yes | no

anthonyfu wrote 11/24/2021 at 13:01 • point

is it possible to modify to measure inductance as low as 1nH, capacitance as low as 1pF?

  Are you sure? yes | no

nqtronix wrote 05/28/2022 at 20:02 • point

With such small values the parasitic inductance/capacitance will dominate and you'd need a much better setup overall. You'd be better of buying a suitable device in the first place.

Sorry for the late reply, hackaday.io's notification system is broken and I didn't get an email.

  Are you sure? yes | no

Does this project spark your interest?

Become a member to follow this project and never miss any updates

Going up?

About Us Contact Hackaday.io Give Feedback Terms of Use Privacy Policy Hackaday API

© 2025 Hackaday

Yes, delete it Cancel

Report project as inappropriate

You are about to report the project "LC100A LC Meter Fix", please tell us the reason.

Send message

Your application has been submitted.

Remove Member

Are you sure you want to remove yourself as a member for this project?

Project owner will be notified upon removal.