Engineering Podcast

MEP EP#21: Let The RF Hit The Noise Floor

Download: MP3
RSS Feed: Link

Runtime: (43:53)

Parker Dillmann
Stephen Kraig

Dustin Holliday

Podcast Notes

  • Dustin Holliday is our guest this week. He was on EP#13 of MEP. Dustin has been working on MacroFab’s KiCad parser and is currently researching the KiCad Python API Documentation.
  • Stephen and Dustin have also been working on a customer test fixture. The fixture can program an entire panel of boards with an ST Link. A brushless motor is attached to the fixture with an encoder to automatically test the boards. See Figure 1.
  • Parker has been working on the Jig Of Destiny REV 3. Parts where ordered on Monday.
  • The SSPS front test panel is complete with minimal hardware mods needed. Parker didn’t get to writing test code for it before the podcast but should have something to show on his twitter by Friday. See Figure 2.
  • Parker got a I2C LCD display working. Ran into an issue but it turned out his SDA and SCL lines for the I2C protocol where backwards. He is using a Saleae DLA to debug the information. See his twitter post about it.
  • Stephen has the analog test board for the SSPS ordered. Has a Pos/Neg rails of 35V, two OPA541 output opamps in parallel, and 0.08 Farads of capacitance. Beefy! See Figure 3.
  • The MacroAmp’s PCB has been completed. Stephen ordered the PCB earlier this week. It is a 2 X 10W tube Hi-Fi stereo using Korg Nutubes as the preamp.
  • The FCC is going to investigate why the RF noise floor in the US has risen in the past years. Parker thinks its the “cost reduction” of devices after being certified. Will this be good or bad for makers? Does import customers have to test devices now? On the plus side, energy harvesting the RF band is more viable!
  • Parker, Stephen, and Dustin get in a rant about Vss/Vdd/Vcc notation for schematics and circuits and Parker offers a solution.
  • The AeroScope is a wireless, ultra-portable oscilloscope that uses Bluetooth 4.1 LE to communicate to a phone or tablet for the screen. Would be useful for Maker style field work. 100Mhz, 500M/samples, +-40V input. Fairly typical specifications. Runs $260 on the crowd funding website.

PCB Test Jig
Figure 1: The test fixture Stephen and Dustin have been working on. Talks to a python script Dustin wrote on the PC.

Figure 2: Front test panel for the SSPS. Code should be working shortly for it. Everything physically fit in the footprints!

Figure 3: MacroAmp Stephen is working on. 3D rendering done in SketchUp.

Special thanks to whixr over at Tymkrs for the intro and outro theme!