X-Y redesign

In version 0.1, there was a pretty major design flaw: instead of sending -9 to +9v to the scanner head, the design I used actually sent 0 to +5v, this was noticeable in that the scanning head made almost no noise.

I’ve just completed a full redesign of the X-Y signal path and here is video (with oscilloscope proof) of the vastly improved signal output to the scanner head.

So just in time for Thanksgiving, we are a major step closer to the beta!

Share

v.0.1.5: rebuild and bug fixes

I just finished building the version 0.1.5 machine.

Here’s what I’ve been working on during the past month and a half:

Electronics:

  • Fixed EAGLE routing flaws (thanks Dorkbot Chicago for a very timely EAGLE CAD class!)
  • Fixed part specification flaws (it turns out that the digital pots I originally used can’t handle much more than 8V, I was giving them 18V – oops!)
  • Built a completely new test machine from scratch, by hand (not as bad as I originally feared)
  • Started an arduino shield based design (using adafruit’s excellent protoshield as a starting point)
  • Started testing the MCP4912 DAC as a replacement for the dual 4911s, I’m currently using.
  • Switched from arduino duemilanove to freeduino/boarduino for physical design improvements (I’d like to use the UNO, but I’m waiting/hoping for improvements in the USB functionality of that board before switching).
  • Added a fast prototyping area for experiments.

Physical:

  • Stopped using magnets as fasteners for the scanning head – those were awful.
  • Built a completely new physical support with improved tripd geometry and stability.

Next up:

  • Redesign the X/Y signal pathway to use the full +/- 9V range and be flexible enough to handle +/- 18V via switch and/or gain adjust (I’m only using +/- 5V now, and it’s not flexible at all).
  • Redesign the transimpedance amp pathway to improve signal/noise ratio and gain.
  • Investigate alternative approach mechanism designs.

Reminder: I’ll be showing the ChemHackerSTM version 0.1.5 at the Armand Hammer Museum in LA on Saturday afternoon/evening as part of CRITTER Salon’s Enormous Microscopic Evening.

Share