EP#145: The Vox in a Box Roxs

EP#145: The Vox in a Box Roxs

  • Stephen's Vox in a Box
    • Preamp Design
      • Vox AC30 preamp - 3 gain stages with a cathode follower and a phase inverter
      • Phase inverter - create differential signals for the power amp input
      • Drop signal using voltage dividers and mosfet buffers
      • 320V phase inverter to 18V buffer drive
      • Built point to point on an aluminum plate for easy modification and testing
    • Power Amp Design
      • TPA3116 Class D amplifier
      • LM311 comparator mute circuit for start up mute ~5 to 10 Seconds
      • Runs at 400KHz - Left open pads for boosting this up to 1.2MHz
        • Is there an advantage at running at higher frequencies?
    • Power Supply Design
      • TPS40210 Switching controller into a diode/cap ladder voltage multiplier
      • 7 stages of multiplication leads to ~50V per stage
      • Variable Switching from 35KHz to 1000KHz
      • PMP8621 Appnote
    • Testing the Vox in a Box
      • Been going nonstop for weeks now
      • Have taken it up to nearly 60 Watts without problems
    • Layout of the PCB
      • Multiple ground system with master start
      • Each sub circuit has its own ground return
      • 8 Master star ground returns
      • 4 layers
    • Issues with the current design
      • High Voltage SMPS does not like high capacitive load
      • Ground for signal input is very important - Nearly all noise is dominated by this single point
        • Alligator clips for signal patching are not low noise…
      • Cold Heater impedance
    • Current Schematic for the Vox in a Box
    • Fusion 360
      • New amp design
        • Learning by building a virtual amp
      • Vox in a box
        • Going to model the whole design to ensure proper fit
  • R.F.O.

Tags: Chris Gammel, electronics podcast, Fusion 360, Hackaday, LM311, MacroFab, macrofab engineering podcast, MEP, PMP8621, Preamp, SuperCon, TPA3116, TPS40210, Vox AC30, Vox in a Box

Episoder(448)

EP#24: Pokey Datasheets and Incognito Arduinos

EP#24: Pokey Datasheets and Incognito Arduinos

Podcast NotesParker and Stephen have been working on the Super Simple Power Supply. Parker has the test panel done and working. See Figure 1. Stephen has the Analog "Energon Cube" PCB made. See Figure...

15 Jul 201636min

EP#23: Interview with Ben Heck of The Ben Heck Show

EP#23: Interview with Ben Heck of The Ben Heck Show

Podcast NotesDactyl nightmare -  One of the first demonstrations of virtual reality used in a video game at the mall of America in the early 90s.Sony/Nintendo console – Before Sony created the Playsta...

8 Jul 20161h 3min

EP#22: Quirky Quadcopters with Scott Shawcroft

EP#22: Quirky Quadcopters with Scott Shawcroft

Podcast NotesScott Shawcroft of Chickadee Tech is our guest on this weeks podcast. He is working on a modular flight control system called polystack. It has 13 different boards that can be stacked tog...

30 Jun 201654min

EP#21: Let The RF Hit The Noise Floor

EP#21: Let The RF Hit The Noise Floor

Podcast NotesDustin 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 ...

24 Jun 201643min

EP#20: I Will Never Know You Viper

EP#20: I Will Never Know You Viper

Podcast NotesMatt Keas is a onboarding instructor over at The Iron Yard. Matt has a background in software and startups. He runs tech related conferences like Space City JS.Brian Dorton is the campus ...

17 Jun 201655min

EP#19: Panning for Caps

EP#19: Panning for Caps

Podcast NotesWith the broken tap removed progress continues on the SAIM. Parker almost has the upper gantry is almost done.The SSPS front panel test is is scheduled to be built next week. Should have ...

10 Jun 201648min

EP#18: Classy Capacitors and Lab War Stories

EP#18: Classy Capacitors and Lab War Stories

Podcast NotesParker has been working on the SAIM (Semi-Automatic Inspection Machine) this week. Work had to pause as Parker broke off a M5 x 0.8MM drill/tap combo bit off inside the extrusion. Should ...

3 Jun 201645min

EP#17: System-in-Package (SiP) Platforms with Greg Sheridan

EP#17: System-in-Package (SiP) Platforms with Greg Sheridan

Podcast NotesThis week Stephen and Parker have a guest. Greg Sheridan of Octavo Systems.Greg is the Marketing and Sales Manager for Octavo Systems.Octavo Systems builds "System-in-Package" or SiP styl...

27 Mai 201636min

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