MEP EP#16: Fixtures of Echoing Tubes

Parker Dillmann |   |, Debouncing, Engineering, IoT, Jig of Destiny, KORG, MakerBeam, MEP, MOnSter 6052, NuTube, Podcast, Prop Fan, Space Echo RE-201, Tubes

MacroFab Engineering Podcast


Download: MP3
RSS Feed: Link

Parker Dillmann
Stephen Kraig


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 NuTubes. The equation for the constant current is I ~ Vgs/Rs.

Figure 4: Jig of Destiny 3D render.

Podcast Notes

  • Parker really wants to get Josh’s (the sound guy) Space Echo RE-201 working. There is a digital filter that simulates the effect though. See figure 1.
  • Stephen received his NuTube’s from KORG this week. See figure 2.
  • To run the tubes, Stephen is going to use a constant current power supply like on page 229 in “Designing High-Fidelity Valve Preamps” by Merlin Blencowe. Stephen really likes this book. See figure 3 for the schematic.
  • Parker has been working on the “Jig Of Destiny” which is a aluminum fixture that is designed to support the large 16″ x 16″ panels used for prototype builds at MacroFab. Test version was made out of 10mm x 10mm MakerBeam material. Production version will be machined out of 3/16″ aluminum to be extra rigid. See figure 4 for a 3D render of the fixture.
  • Parker’s new board was completed by MacroFab today. It is a fan and system controller for his Jeep. Hardware and software will be open source as always. Picture of the board can be seen here.
  • While testing the PCB board, Parker noticed there was a 0.03V over the power cables. Stephen calculated it out. See below for the calculations. The drop is most likely coming from the spring contact in the clip.
  • has a nice article about hardware and startup jargon used in the industry. Parker and Stephen pick through it.
  • Stephen and Parker rant about connector datasheets again. This time about connectors that need multiple parts to be used. Example of this would be connectors that have separate conductor pins.
  • Amazon released a programmable version of their IoT Button.
  • The MOnSter 6502 is a discrete level 6052 CPU. Parker thought it would be bigger. It has over 4000 discrete transistors.
  • On the note of 6502 CPUs, there is a really cool visual 6502 online simulator.
  • Stephen and Parker discuss where debouncing a switch should be done in Hardware or Software.


12.01V from power supply
11.98V at input of circuit
60mA current draw so
0.03/0.06 = 0.5ohms resistance
But that is across two wires so 250mOhms per wire or 0.083mohm per foot
33 AWG wire matches this but that is fairly thin.

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