v2.9-beta.2 -

What's Changed

• Stabilized Analog Chain closing #7
• Tie geophone negative terminal directly to GNDREF, eliminating the DC-bypass filter previously needed.
• Gain control is now linearized, but needs calibration to account for resistor and digipot tolerances.

Full Changelog: v2.7...v2.9-beta.2

Version 2.7

Essentially the same as v2.5 (and v2.6) with minor tweaks and file format updates for the current version of KiCad.

v2.5 Final Revision

Final v2.5 version, Deployed at USMARC.

Fabricatable with Cheaper Gain Pot

Switch to MCP41010 gain pot, which is available at JLCPCB

Faster Fab with more common parts

I've eliminated every specialty part I can except for the gain resistor (there's only the one option with <5% tolerance), so this should be more manufacturable. Also, we're back to JLCPCB because PCBWAY was super slow, but there's no need to loosen the tolerances.

Single-ended Analog Chain

Switched to PCBway design rules (slightly more stringent than JLC).

Since the SM-24 geophones are apparently single-ended outputs (found from experimentation), the analog chain is simplified to account for that.

Minor fab updates

v2.5-beta.2

Added Tooling Holes for JLCPCB SMT assembly

First UMich Version

After all the checking and tweaks, this is ready for a short run and hardware testing.