I dug up this image of the CR2032 tester with a coin cell inserted.
The coin cell doesn’t have to be inserted completely for the tester to work, which
reduces test time (no need to mess up/bend fingernails prying the battery out too).
The next best thing to add to this design would probably be a plastic non-conductive
ejection system. But i’m not in the business of testing lots of coin cell batteries (yet).
The 9V attachable electroscope has been updated. The silkscreened date on the
back for this version is 2014-08-24(!)
- Pulled copper pour near inputs back
- Removed polyimide/kapton shield
- Simplified antennae construction
One slight quirk with nearly all of these electroscopes is that they appear
to be hard ‘on’ after assembly sometimes. In many cases i’ve found that this is
due to residual flux (of the water washable type).
I’ve had success by scrubbing down with isopropyl alcohol and reflowing
again with hot air.
You can find the necessary sources, gerbers, and files here. The BOM is identical to the older version.
The OSHPark shared project for direct fabrication can be found here.
I was able to release a small breakout board based on a sample I received long ago from Texas Instruments.
It is a CR2032 tester, based on the pretty accurate TPS3809L30DBVR part (which was derived
from eevblog’s µCurrent). The LED stops lighting up somewhere slightly at or below 2.64v, where most CR2032 coin cells enter
end-of-life on the discharge curve.
Read more and get it made on the project page.