Fixtures of Echoing Tubes

May 20, 2016, Episode #16

• 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.
• Bolt.io 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.

Calculations

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.

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.