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Revision
TEXAS A&M UNIVERSITY
Electrical & Computer Engineering
Multi-parameter
Tester User Guide
TEXAS A&M UNIVERSITY
Multi-parameter Tester User Guide
By: Team Dos
Samuel Reyna
Joshua Austin
Richard Olivo
Jason DeVout
Table of Contents
Overview .................................................................................. 1
Device Diagram........................................................................ 2
Operation ................................................................................. 3
To Turn On/Off ......................................................................... 3
Measuring Temperature ........................................................... 4
Measuring Pressure ................................................................. 5
Measuring Water Conductivity.................................................. 5
Measuring Speed (in RPM) ...................................................... 6
Troubleshooting and Calibration............................................... 8
Temperature ............................................................................ 8
Pressure................................................................................... 9
Water Conductivity ................................................................... 9
Speed (in RPM)........................................................................ 9
Battery Charging/Monitoring ..................................................... 9
Bill of Materials ....................................................................... 11
Main Board............................................................................. 11
Pressure Sensor Board .......................................................... 12
Water Conductivity Circuit Board ............................................ 12
Temperature Sensor Board .................................................... 13
Speed/RPM Sensor Board ..................................................... 13
Battery Charging Board .......................................................... 13
Battery Monitoring Board........................................................ 14
Ratings and Warnings ............................................................ 15
Ratings ................................................................................... 15
Warnings ................................................................................ 15
Appendix ................................................................................ 17
Temperature Sensor Circuit Schematic .................................. 17
Pressure Sensor Circuit Schematic ........................................ 17
Water Conductivity Circuit Schematic..................................... 18
Speed Sensor Circuit Schematic ............................................ 18
Charging &Powering Circuit Schematic .................................. 19
Acknowledgements ................................................................ 20
D E S I G N
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Chapter
C U S T O M I Z A T I O N
Overview
This section presents the device needs and an overview of
functionality.
T
his Multi-paramater Tester serves to ensure proper operation of various pieces
of hospital lab equipment in low-resource settings.This is achieved by
measuring four parameters: temperature, pressure, water conductivity, and
speed. It to be primarily used for the following:
Temperature
 Refrigerators
 Incubators
Speed
 Centrifuges
Water Conductivity
 Distillers
Pressure
 Sphygmomanometer
It may also be used for devices other than the ones mentioned, so long as the
guidelines in this manual are followed. By measuring these parameters technicians are
able to determine if the piece of equipment is functioning properly and make
adjustments accordingly. This prevents malfunction, inaccurate results, and ultimately
loss of expensive medical equipment.
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Device Diagram
Touch Screen
LED Battery Indicators
Power Switch
Pressure Sensor
Power LED
Charging LED
Figure 1 - Front of Multi-parameter Tester
Temperature and RPM sensors located at back of device; Water purity probe located at
the top of the device.
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2
Chapter
Operation
This section ensures proper operation of device.
To Turn On/Off
To turn device on, locate the power switch on the front of the device and switch to
either power source.
Figure 2 - Power Switch at Replaceable Battery position
By switching to the left side, the device uses the rechargeable batteries to run, while
switching to the right side allows device to be powered by the AA replaceable batteries.
To power off, simply move the switch back to the middle.
Once device is turned on, the touchscreen will display the main menu as shown below:
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Figure 3 - Main menu
To choose parameter to be measured, press firmly on the virtual button on screen
indicating that parameter.
Measuring Temperature
To measure temperature, press button on main menu reading ‘Temp’. The screen will
now change to indicate the temperature in the default unit (Fahrenheit) received from
the sensor located on the back of the device.
Figure 4 - Temperature Screen
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The ambient temperature will be displayed in units of Fahrenheit and Celsius. To go
back to the main menu, press the ‘Back’ button on the lower left corner of the screen.
For a proper temperature reading, place the device inside the environment to be
measured for at least 5 seconds.
Measuring Pressure
For measuring pressure, press button on main menu indicating ‘Press’. The screen will
now change to indicate the pressure in units of mmHg received from the sensor at the
front of the device.
Figure 5 - Pressure Screen
To obtain a proper pressure reading, make sure rubber tube being used for calibration
fits snugly onto the pressure sensor.
To go back to the home screen, press the lower left corner of the screen.
Measuring Water Conductivity
To measure water conductivity (for purity), press button on main menu indicating
‘H2O’. The screen will now change to indicate the status of water conductivity/purity
being sensed by the probe.
Unwind probe cable from side of device. Place probe in the water to be tested, until it
is completely submerged. Maintain probe in this position for at least 5 seconds to
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obtain a proper reading of the sample. Once status of water is given, remove the probe
from the water, dry with a cloth and securely wind cable back onto cable holders.
WARNING:
The water conductivity probe looks like a standard two-prong wall plug;
however, it does not supply power. DO NOT ATTEMPT TO PLUG
PROBE INTO WALL OUTLET. DOING SO MAY RESULT IN
DEVICE FAILURE.

If the probe is not in water, the screen will change to indicate ‘Not in Water’.

If screen indicates ‘Pass’, water being tested is pure/clean; distiller is working
properly and water is good for use.

If screen indicates ‘Fail’, water being tested is unclean/dirty; distiller is not
working, do NOT use water.
Figure 6 - Water Purity Screen demonstrating that probe is not in water
To go back to the home screen, press the lower left corner of the screen.
Measuring Speed (in RPM)
To measure speed (in revolutions per minute), press button on main menu indicating
‘RPM’. The screen will now change to indicate the speed of the object being calibrated.
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Figure 7 - Screen showing a sample RPM
For a proper speed reading, ensure that the optical sensor located on the back of the
device is directly on top of spinning object. Furthermore, to get the right speed, the
object being measured (e.g. a centrifuge) should have only one section/strip of
reflective material (or non-reflective if surface is metal) going from the center of the
spinning object to the edge. Modifying this may cause a speed measurement higher
than the actual speed of the object. Maintain device steady in this position until speed
reading on the screen is stable/constant.
Once speed is measured, you may go back to the home screen by pressing the lower
left corner of the screen.
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3
Chapter
Troubleshooting and
Calibration
Fixing potential problems and ensuring correct measurement.
T
His device has been designed to give accurate measurements even in poor
conditions; however, should the device begin failing at any time the following
steps will aid in the repair of each sensor. To determine if any of the sensors
are malfunctioning, follow these guidelines:

Pressure sensor should read about 40 mmHg (may be unstable due to noise)
with no pressure from tube. If reading fluctuates too much from this, sensor
circuit is malfunctioning.

If temperature shown on screen is obviously inaccurate (reads 170 ºF when it
should be 70 ºF) then temperature sensor circuit must be adjusted/repaired.

If water conductivity reads ‘Not in Water’ while probe is in water, or reads
‘Pass’ for dirty water, troubleshooting must be done.

If screen shows a high speed when the RPM sensor is not measuring a
spinning surface, the speed sensor circuit and algorithm must be checked.
Temperature
If the temperature output is not working correctly, the first thing to do is to
measure the resistance of the RTD. Unpowered, and near room temperature, the
RTD should have a resistance of approximately 2000 ohms. The second step is to
measure the incoming power to the sensor circuit board. Reference the schematic,
and make sure that the three sources are the correct value. If one of the voltages is
incorrect, then the regulators need to be checked. Once the power has been
observed to be correct, measure the voltage on the supply terminals of the
operational amplifier and the instrumentation amplifier. The output of the sensor
board can be calibrated by tuning the potentiometer on the top left side of the
circuit board.
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Pressure
If the pressure output is not working correctly, the first thing to do is to measure the
resistance of the pressure sensor between the “Icc” and “GND” pins. Unpowered, the
pressure sensor should have a resistance of approximately 20.000 ohms. The second
step is to measure the incoming power to the sensor circuit board. Reference the
schematic, and make sure that the three sources are the correct value. If one of the
voltages is incorrect, then the regulators need to be checked. Once the power has been
observed to be correct, measure the voltage on the supply terminals of the operational
amplifier and the instrumentation amplifier. The output of the sensor board can be
calibrated by adjusting the processing equation in the microcontroller software.
Water Conductivity
If the temperature output is not working correctly, the first thing to do is to measure
the resistance of the probe. Disconnected from the circuit, the probe should be an
open circuit and have an infinite resistance. The second step is to measure the
incoming power to the sensor circuit board. Reference the schematic, and make sure
that the two sources are the correct value. If one of the voltages is incorrect, then the
regulators need to be checked. Once the power has been observed to be correct,
measure the voltage on the supply terminals of the operational amplifiers. The first
potentiometer in the schematic allows you to calibrate the Wien Bridge Oscillator that
generates the AC waveform. The amplitude of the signal generated at the output of the
first op-amp needs to be approximately 20Vpp. The third potentiometer sets the bias
for the zero point pressure. Change the pot until the output at zero pressure is
approximately zero.
Speed (in RPM)
If the pressure output is not working correctly, the first thing to do is to make sure the
phototransistor on the optical sensor still operates. Unpowered, the phototransistor
should be an open circuit with zero voltage output. The second step is to measure the
incoming power to the sensor circuit board. Reference the schematic, and make sure
that the source is the correct value. If the voltage is incorrect, then the regulator needs
to be checked. Once the power has been observed to be correct, measure the output
voltage when a reflective surface is within a few millimeters of the sensor. The output
of the sensor board can be calibrated by adjusting the processing equation in the
microcontroller software.
Battery Charging/Monitoring
If the led indicators on the battery charging system do not turn on, or if the system
does not seem to be powering the NiMH battery, check the voltage at the input of
the Smart Charging Circuit board to see if the circuit is in fact receiving voltage.
The Smart Charging Circuit is set to charge the NiMH battery at 500 mA.
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Disconnect the incoming voltage jumper from the PCB and place an ammeter in
series with the jumper and ensure that the board is pulling 500 mA when charging.
Second, measure the output voltage of the circuit to see if the voltage is indeed
leaving the circuit. If the Smart Charging Circuit is not outputting proper voltage or
current, replace the IC along with the two BJ Transistors.
If the battery monitoring system does not indicate the system’s voltage through the
LEDs, check to see if the Monitoring PCB is receiving voltage. If the board is
receiving voltage, check to see if all LEDs are connected to the board. If every
component seems fine, then the IC may need to be replaced.
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4
Chapter
Bill of Materials
List of parts for repair of device.
T
his section list all components of the device according to the individual PCBs
found within the enclosure. All sensor, battery, and processing boards are
attached to the main PCB board, which is fixed onto the enclosure with 4
clips. The temperature, speed, and water conductivity boards are found on the
bottom of the board, while the remaining boards (including the microcontroller and
screen) are found on the top side. Components with more than one of the same
element are denoted with (#).
Main Board
Components:
 NiMH Battery Pack: 14.4 V 2200mAh ( 31.68 Wh, 12xAA)
 Battery Holders, Clips & Contacts 10XAA TABS BLK
 Slide Switches Mini slide vertical actuator SP4T
 LM7805 +5V Voltage Regulator
 LM7812 +12V Voltage Regulator
 LM317T Adjustable Voltage Regulator (2)
 755-BP5122 Negative DC/DC (-12V) Converter/Regulator
 0.1 uF capacitors (5)
 1 uF capacitors (6)
 240 ohm resistor
 430 ohm resistor
 1.6 kohm resistor
 82 ohm resistor
 DC PWR 2.1 MM Gray Kobiconn Connector for DC Power
 PCB 2.1 MM Kobiconn Connector
 Samsung Replacement 19V, 3.16 A 60W AC Adapter
 TI Stellaris LM4F120 LaunchPad Evaluation Board (EK-LM4F120XL)
 Kentec Display Stellaris LaunchPad LCD Boosterpack EB-LM4F120-L35
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Pressure Sensor Board
Components:
 2SMPP-03 OMRON Pressure Sensor
 INA126PAMicroPOWER Instrumentation Amplifier IC
 LM1458N TI Dual OPAMP IC
 2N2222 BJ NPN Transistor
 1N4001 Diode
 TC54VC42 Microchip Voltage Detector
 500 ohm resistor
 10 kohm resistor
 100 kohm resistor
 1.4 kohm resistor
 1 kohm resistor
 100 ohm resistor
Water Conductivity Circuit Board
Components:
 LM1458N TI Dual OPAMP IC (3)
 1N5227 Zener Diode, 3.6V
 1N4148 Diode, GP Silicon (4)
 2N2222 BJ NPN Transistor
 TC54VC42 Microchip Voltage Detector
 0.22 uF capacitor
 0.15 uF capacitors (2)
 100 kohm potentiometer
 2 kohm potentiometer
 22 kohm potentiometer
 33 kohm resistor
 1 kohm resistors (5)
 100 kohm resistors (3)
 56 kohm resistor
 0.22 Mohm resistor
 6.8 kohm resistor
 22 kohm resistor
 220 kohm resistors (3)
 82 kohm resistor
 2 kohm resistor
 380 ohm resistor
 200 ohm resistor
 6.3 kohm resistor
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Temperature Sensor Board
Components:
 INA126PAG4 MicroPOWER Instrumentation Amplifier IC
 LM1458N TI Dual OPAMP IC
 TD5A RTD Temperature Sensor
 2N2222 BJ NPN Transistor
 TC54VC42 Microchip Voltage Detector
 1N4001 Diode
 LM7805 +5V Voltage Regulator
 50.5 kohm resistor (2)
 7 kohm resistor
 4 kohm resistor
 9 kohm resistor
 28 kohm resistor
 68 kohm resistor
 680 ohm resistor
 6.3 kohm resistor
 10 kohm potentiometer
Speed/RPM Sensor Board
Components:
 TRCT5000 Vishay Optical Reflex Sensor
 15 kohm resistor
 180 ohm resistor
Battery Charging Board
Components:
 2N4403 Fairchild PNP General Purpose Amplifier
 MAX712 NiCd/NiMH Battery Fast-Charge Controllers IC
 2N2222 BJ NPN Transistor
 1N4001 Diode
 10 uF capacitors (2)
 1 uF capacitor
 22 nF capacitor
 150 ohm resistor
 10 kohm resistors (2)
 1 kohm resistor
 2.2 kohm resistor
 500 ohm resistor
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



33 kohm resistor
470 ohm resistor
0.3 ohm resistor
Red LEDs (2)
Battery Monitoring Board
Components:
 LM3914 TI Dot/Bar Display Driver IC
 56 kohm resistor
 200 kohm potentiometer
 10 kohm resistor
 Red LEDs (2)
 Yellow LEDs (3)
 Green LEDs (5)
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5
Chapter
Ratings and Warnings
Taking proper care of device and preventing malfunction.
Ratings
This device was designed to accurately measure each parameter within the
following ranges:

Temperature: 0°-100° C ( 0.1° resolution)

Water Conductivity: 0 –99 uS

Pressure: 0-300 mmHg

Speed: 200-100,000 RPM (60 RPM resolution)
Attempting to measure any parameter beyond the above ranges may lead to
inaccurate measurements or damage to the sensors.
Warnings
General:
1.
DO NOT shake or throw device with excessive force. This may cause
component damage and ultimately failure of device.
2.
Keep device in a dry place at room temperature. Except for the water
conductivity probe, device is not designed to be in wet or damp
environment.
3.
DO NOT press hard on touch screen or use sharp object to press the on
the screen. Doing so may pierce it and leave it unusable.
Water Conductivity Probe:
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1.
DO NOT plug probe into wall outlet. Doing so may result in device
failure.
2.
Properly wind probe cable back onto holder to prevent cable from being
stretched and detached from device.
3.
Dry probe completely before winding it back to prevent other
components from getting wet.
Temperature Sensor:
1.
Avoid touching temperature sensor in the back of the device. Moving or
touching sensor could cause improper readings and sensor malfunction.
2.
Do not remove protective metal clip from enclosure. Doing so leaves
temperature sensor vulnerable to bending/breaking.
Pressure Sensor:
1.
When adjusting tube to pressure sensor, make sure to not press into sensor
roughly in order to prevent sensor from being pushed into the enclosure.
2.
Keep sensor and surrounding area clean, any dirt/debris that falls inside
the sensor may affect performance.
Speed/RPM Sensor:
1.
Do NOT cover sensor when measuring the speed of an object. Doing so
will prevent speed reading.
2.
Do NOT place several reflective/non-reflective strips on surface of object
being measured; this will cause the device to output a higher speed than
what the object is actually spinning at.
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Appendix
Temperature Sensor Circuit Schematic
Pressure Sensor Circuit Schematic
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Water Conductivity Circuit Schematic
Speed Sensor Circuit Schematic
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Charging &Powering Circuit Schematic
(Continued)
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Acknowledgements
We would like to acknowledge the Biomedical Engineering students
involved in the design of this project: Mason Cote, Romina del
Bosque, Hailey Marsh, and Jonathan Franks.
We would also like to acknowledge the graduate students assisting
during the design process for their input: ShafeeqShajudeen from
the Electrical Engineering Department and Kristen Duckworth
from the Biomedical Engineering Department.
Furthermore, we would like to give a special acknowledgement to
our faculty sponsors: Dr. Samuel Villarreal from the Electrical
and Computer Engineering Department and Dr. Kristen
Maitland, from the Biomedical Engineering Department.
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