I designed this high-speed data acquisition board for AerospaceNU's liquid rocket engine test stand during Summer 2022. The electronics successfully gathered data during a hotfire during October 2022.
The PCB was designed to validate data acquisition designs for the club's eventual liquid-propelled rocket, and replace the interim breadboard solution designed during Spring 2022. The design exceeded our requirements on connectivity, data acquisition rate, and resolution.
The sensor board has inputs for:
- 15 pressure transducers, either 4-20mA or 0-5v (configurable), at up to 1.5KHz
- 4 type-K thermocouples
- 1 loadcell (configurable gain)
The sensor board can be seen installed inside the electronics box of the test stand, which also houses power supplies and pneumatic solenoids for valve actuation, below.
I did schematic capture and PCB layout in KiCad 6, my new favorite EDA program. I used a layout replication plugin in KiCad to quickly replicate the input filter layout (shown below) 15x.
Input voltage divider and filter for current- and voltage-output pressure transducers, selectable my moving a solder jumper. Includes TVS diodes for input protection, and a rail-to-rail opamp to drive ADC inputs.
The passives on the back of the PCB (above, middle) were placed by JLCPCB, and ICs were hand-soldered. The MCP3564 was particularly troublesome in its 20-UQFN (3x3 mm) package (above, right; 0603 capacitors for scale).
