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

Jaksot(448)

EP#16: Fixtures of Echoing Tubes

EP#16: Fixtures of Echoing Tubes

Hosts: Parker Dillmann Stephen KraigGuests: N/A Figure 1: Non working Space Echo RE-201 Figure 2: A NuTube 6P1 straight from KORG. Figure 3: The constant current source Stephen is using for his NuTub...

20 Touko 201643min

EP#15: Ridiculously Blinking LED

EP#15: Ridiculously Blinking LED

Hosts: Parker Dillmann Stephen KraigGuests: N/A Figure 1: SSPS front panel test layout. Miniature version of the real front panel to test physical placement and new parts. Figure 2: Two TPS65982-EVM b...

13 Touko 201633min

EP#14: Discrepant Diodes

EP#14: Discrepant Diodes

Hosts: Parker Dillmann Stephen KraigGuests: N/AFigure 1: SSPS front panel layout. Traces to come soon. Figure 2: Inconsistencies in the LTST-C171CKT datasheets.Podcast NotesStephen is still working on...

6 Touko 201635min

EP#13: Picture Books for Engineers

EP#13: Picture Books for Engineers

Podcast NotesOur guest this week is Dustin Holliday, a Production Line Engineer at MacroFab, INC. Dustin programs the My200 paste jetter, the My500 pick and place, and the Rhythm Selective Solder. See...

29 Huhti 201640min

EP#12: Silicon Condensors

EP#12: Silicon Condensors

Podcast NotesStephen built a power supply for an old school tube microphone for Josh. Josh does the recordings for the Podcast. See Figure 1 for the schematic.Microphone is a Sony C37 tube condenser m...

22 Huhti 201630min

EP#11: False Fuses and Kitschy Kickstarters

EP#11: False Fuses and Kitschy Kickstarters

Podcast NotesParker has been hard at work on the PinHeck Test Fixture. It uses over 160 pogo pins to test every single function of the PinHeck Pinball System. There will be an article about designing ...

15 Huhti 201637min

EP#10: IoT’s Cloudy Future

EP#10: IoT’s Cloudy Future

Podcast NotesFirst Guest for the MacroFab Engineering Podcast! Trey German is working on a IoT platform using BLE and a small coin cell.Trey's device worked on the first revision! How often does that ...

8 Huhti 201641min

EP#9: Robots with Feelings

EP#9: Robots with Feelings

**Podcast Notes*** Parker and Stephen continue work on the [Super Simple Power Supply](https://github.com/MacroFab/SSPS). There is a full on simulation of the analog section on MultiSim.* Stephen foun...

1 Huhti 201636min

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