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#116: Standard-ish

EP#116: Standard-ish

StephenUsing an oscilloscope as a dynamic signal analyzerAnalog scopesParkerGameboy update Code compiles! Quartus II still compiled my Gameboy Project1.25mm? pitch 21 pin. Connectors are hard to find....

18 Apr 201852min

EP#115: From A Current Perspective

EP#115: From A Current Perspective

StephenLM13700Dual Operational Transconductance Amplifiers With Linearizing Diodes and Buffers built by Ti?All passive filterNot just a zero ohm resistor ;)Shift the phaseFixing a Kegerator Kegerator ...

12 Apr 201847min

EP#114: Chasing Oscillations

EP#114: Chasing Oscillations

StephenNasty Analog Oscillations Opamps are drama queens of electronicsSolved the oscillation with a small capacitor in the feedback loop to lower the frequency of the feedbackParkerWaiting on circuit...

4 Apr 201845min

EP#113: Put All Your Power On Blue

EP#113: Put All Your Power On Blue

StephenAutoDesk Fusion 360Fusion 360 Tutorial by Lars ChristensenParkerGetting the PCM5122 DAC to talk to an ArduinoanalogRead FAST Cuts the number of cycles needed to do an Analog read on the Arduino...

28 Mar 20181h 1min

EP#112: Bruce Hamby and Owning Your Product

EP#112: Bruce Hamby and Owning Your Product

Bruce HambyAttorney with the Hamby Law FirmThe Hamby Law Firm focuses on patents, intellectual property, trademarks and business lawHas been an attorney in the Houston region for over 15 yearsOwn your...

21 Mar 201857min

EP#111: Logic Commander

EP#111: Logic Commander

Stephen"Slow Start" or soft start circuitsBulk capacitance is killing the power supply for the new synth designCapacitance MultiplierParkerBadge Design for DefCon NFC Belt BuckleLots of LEDs of course...

14 Mar 201839min

EP#110: Dangling Transformers

EP#110: Dangling Transformers

StephenRibbon Microphone Turn it into a Hackaday.io project?Make a USB microphone from scratch? PCM2912ATalked about this IC on a previous episode of the MEPDatasheetStephen will be in Denver next wee...

7 Mar 201838min

EP#109: Arduino, The Gateway Drug To #BadgeLife

EP#109: Arduino, The Gateway Drug To #BadgeLife

AND!XORCheck out the previous MEP EP#69 Incognito Mode for the last time the AND!XOR group was on the podcastBitstr3mDid the Android mobile application for the DEFCON 25 badgeZappDoes the hardware des...

1 Mar 201848min

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