The CR2032 tester in action

 On 2015-03-12 and filed under: cr2032 tester breakout pcb hardware

I dug up this image of the CR2032 tester with a coin cell inserted.

coin cell tester in action

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).

Electroscope update

 On 2015-02-10 and filed under: electroscope toy pcb hardware

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.

Updated electroscope


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.

CR2032 tester

 On 2014-06-29 and filed under: cr2032 tester breakout, pcb hardware

CR2032 tester

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 ĀµCurrent). 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.