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Dissolved Oxygen Monitor

Dissolved Oxygen Monitor. Senior Design Dec1211. Team Members: Andrew Beougher Anthony Swope Hao Wang I- chun Chao Bing Bai Colin Hicks. Measures the concentration of dissolved oxygen (DO) Uses the photoluminescence (PL) of a

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Dissolved Oxygen Monitor

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  1. Dec1211 Dissolved Oxygen Monitor Senior Design Dec1211 Team Members: Andrew Beougher Anthony Swope Hao Wang I-chun Chao Bing Bai Colin Hicks

  2. Measures the concentration of dissolved oxygen (DO) • Uses the photoluminescence (PL) of a • Platinum-Octaethyl-Porphyrin (PtOEP) Polystyrene film • Major components: • Sensor Control Unit (SCU) • Sensor Probe Dec1211 Dissolved oxygen monitor

  3. Applications • Waste water treatment • Marine ecologies • Fermentation Dec1211 Dissolved oxygen monitor

  4. Re-engineer current design by removing or changing existing components. • Lowering power consumption • Adjusting system timing of the sensor Dec1211 DesignObjectives

  5. Functional • Water proof sensor probe, water resistant SCU enclosure • Measurement range of 0-20ppm DO • Local and remote control operation • Microcontroller shall determine the dissolved oxygen level over 1 second • Long battery life during discontinuous operation • 5 samples every 5 minutes • Operating duration of at least 30 days • Probe: • Submersible to 100 ft. • Operational range of 0-50ºC Dec1211 DESIGNRequirements

  6. Non-functional • Local multi-character LCD • Indicator lights • Handheld / Portable Dec1211 designRequirements

  7. Dec1211 SystemCurrent Design

  8. Dec1211 SystemProposed Design #1 Dual Supply System

  9. Dec1211 SystemProposed Design #2 Single Supply System

  10. Dec1211 SystemSignalamplification Previous design

  11. Photodiode • Pre-amp • Current to Voltage • 4 LED’s • 525nm • LED driver • Temperature sensor Dec1211 SystemSensor Probe

  12. Dec1211 Systemsensor probe

  13. Excite PtOEPfilm • Sample the decay using the microcontroller • Calculate using least-squares exponential fit • Calculate DO using simplified equation with temperature dependent variable a and b Dec1211 softwareOperating theory

  14. Dec1211 softwareCurrent sensor timing

  15. Dec1211 softwareProposed sensor timing

  16. Microcontroller • ATXMega128 • LED Current Driver • MAXIM3699 • TPS61042 • LT1932 • DC-DC Converters • ADP150/151 • TPS61006 • MAX1763 Dec1211 HardwareProposed components

  17. MAX3699 • 10 port PWM • 0.7 A standby current • TPS61042 • 83% efficiency • Output voltage protection • LT1932 • Input voltage of 1.0V • 0.1 µA standby current Dec1211 HardwareLED drivers

  18. Why drive with current and not voltage? Dec1211 HardwareLED Current Drivers

  19. Benefits of constant current • Can provide a more accurate representation of power consumption • LEDs will not burn out due to over current • Constant luminosity of LEDs for accurate readings Dec1211 HardwareLED Current Drivers

  20. Output voltage of 3.3 V: • ADP150/151 • 10 µA quiescent current with 0 load • Requires minimum 3.7 V • TPS61006 • Can operate as low as 0.8 V • Low battery indicator • ~50 µA quiescent current with 0 load • MAX1763 • ~88% efficient at input voltage of 1.2 V Dec1211 HardwareDC-DC converters

  21. 3 potential configurations Dec1211 HardwareBattery configurations

  22. Issues of parallelism: • Can increase available Amp hours • One side becoming a sink or source • Need to keep levels equal • Use a diode to help regulate levels • Performance benefits of using batteries in parallel • Cost of power loss through diodes • Benefit of increased Amp hours Dec1211 HardwareBattery configurations

  23. Dec1211 Hardware battery configurations

  24. Power System: • Power efficiency • Current output • LED driver: • Startup times • PWM output • Actual vs. computed current output • Microcontroller: • Power consumption of different modes Dec1211 Testingcomponents

  25. Test individually to derive accurate representation of the current used. • Monitor the current drawn by the supplies in various modes of operation. Dec1211 TestingPower systems

  26. Speed test for start times • Check the output wave form for ripple Dec1211 TestingLED system From tps61006 data sheet.

  27. Test the current use in different modes • Data Collection • Calculation • Idle Mode • Power-Down Mode Dec1211 Testingmicrocontroller

  28. Full System Test: • Long term battery duration Dec1211 TestingSystem

  29. Dec1211 TestingSystem

  30. Evaluate system operation • Update customer requirements • Perform component testing • Create preliminary circuit board revisions Dec1211 Projectcurrent Status

  31. Andrew Beougher • Group leader, soldering, parts ordering, Cy-point server, organize meetings, edit and finalize documentation • Anthony Swope • Weekly reports, testing power supply components, sensor probe design • Hao Wang • Updating website, testing power supply components Dec1211 Projectcontributions

  32. I-Chun Chao • Research the LED driver parts and do the marketing research • Bing Bai • Improve the performance of current software design, develop testing program on different operation mode. • Colin Hicks • Production of documents, research of parts, design of test conditions, investigation of wireless communication. Dec1211 Projectcontributions

  33. Finalize new circuit board version • Assemble new circuit board • Perform long term battery duration tests • Perform application and calibration testing • Test programming modifications • Re-integrate wireless communications Dec1211 projectfuture plans

  34. Questions? Dec1211

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