Project Idea 1: Smart Kegerator

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The Smart Kegerator EE-595 Group 1 Brandon
Bartell Nick Sneha Juvekar Anthony Hector
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Insert Picture Slide of Group Members Here
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Project Smart Kegerator

• Refrigerating, dispensing, and monitoring device
  for compressed fluids
• Displays temperature
• Displays liquid content
• Prevents unauthorized usage

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Project Smart Kegerator
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Project Smart Kegerator

Temperature sensor
Display
Power Supply
Signal Conditioner
Scale / Converter
Keypad/Security
Flow solenoid
Nick
Hector
Brandon
Sneha
Anthony
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Performance Requirements

• Keypad Matrix 3 columns, 4 rows
• Key Definitions 0-9 digits, enter, clear
• Sensory Temperature and Weight
• Temperature accurate within 0.5 C
• Weight Scale accurate within 0.8 lbs

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Performance Requirements

• Power Modes ON/OFF
• Power Saving Modes Standby

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Standard Requirements

• Operating Temperature Range 10C to 32.22C
• Operating Humidity Range 0-100 Non condensing
• Operating Altitude Range -300ft to 15,000ft
• Storage Temperature Range -50C to 65C
• Storage Humidity Range 0-100 Non condensing
• Storage Pressure Range 0.5 to 1.5 ATM
• Sources 120 VAC
• Power Consumption 74 W

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Standard Requirements

• Volume 17.6 ft3
• Shipping Container Size 31in.68in.28in.
• Mass fridge plus add-ons
• Maximum Parts Count 50 parts
• Maximum Unique Parts Count 20 parts
• Full Warranty Period 1 years
• Service Strategy Field Repair or Dispose
• Product Life 20 years or more

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Key Technical Risk Problem Areas

• These are some key technical risks that we
  believe might hamper our overall efforts
• Sensor interfacing
• Programming language selection - integration
• Potential long lead time on various components
• Size of prototype (transportation, work space
  availability)
• Component response to low temperatures
• Power supply interfacing (step-down transformers,
  AC\DC conversion)
• Signal control and processing
• Microcontroller limitations
• High costs of components and supplies

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EMC Standards

• IEC 6100-3-3 Limitation of voltage fluctuations
  and flicker in low-voltage supplies lt16A
• Required because a low end voltage flicker could
  damage the compressor
• IEC 6100-4-5 Surge Immunity tests
• Required because the microcontroller and other
  components need to be protected from potential
  power surges
• IEC 6100-4-11 Voltage dips, short interruptions,
  and variations
• Required because brown out conditions will affect
  keypad thereby affecting overall performance

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Safety Standards

• CSA C22.2 No. 14-95
• Applies for control and protective devices.
  Control devices covered in this standard include
  pushbutton flow-, pressure- operated switches
  and proximity switches.
• IEC 60335-2-34
• Applies for the safety of motor-compressors,
  their control and protection system which are
  intended for household purposes.
• UL 873
• Temperature-Indicating and -Regulating Equipment
  requirements for electrical equipment for control
  for refrigeration

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Specific Safety Requirements

• Ground Fault Circuit Interrupter (GFCI)
• Connected in series with the power source.
  Needed because there will be electronics in a
  potentially wet environment the sensors near the
  keg.
• Anti-tipping Mercury Switch
• If the kegerator tips over, this will turn off
  the compressor.

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Example of Simple Gantt Chart showing
dependencies
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Block Prototyping Plan Template
Block Name Block Area (cm2) Total PCB Area (cm2) PCB Substrate Type Comp Attachment Type Socketed Components Types of Connectors
Nick 72 65 Plastic, pads, buses Solder Relay, resistors, LEDs IEC, Circular, PCB Mount
Hector 204 194 Plastic, pads, buses Solder Diodes, resistors, capacitors, etc. IEC, PCB mount
Sneha 105 92 Plastic, pads, buses Solder ICs, LEDs IEC, PCB Mount
Anthony 81 66 Plastic, pads, buses Solder ICs, Relays IEC, Circular, PCB Mount
Brandon 112 101 Plastic, pads, buses Solder Diodes, IC, resistors, capacitors, IEC
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Block Prototyping Plan Template

• The PCB will have pads and a bus
• All socketed components will be soldered or din
  rail mounted
• All Connectors will be IEC, Circular, or PCB
  mount.
• A minimum of 10 components will be used by each
  block

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Block Prototyping Plan Template

• Estimation Summary
• 1277.8 Estimated vs 400 availability.
• 674.00 Estimated vs 600 available investment
• 3.29 of total manpower for system design tasks,
  detailed design tasks, verification tasks, and
  documentation tasks
• Suggested down/up scope if needed
• Added CPLD Control, Electronic Pressure
  Regulator, Volume/Flow Control

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Temperature Sensor Block

• Owner Anthony Futterer

The purpose of the temperature sensor is to
monitor the temperature inside the kegerator
unit and serve to inform the user via the display
block of the temperature in degrees C.
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Performance Requirements

• Accurate to 0.5 degrees C.
• Provide a user mountable probe device for
  internal placement.
• Provide an inline shielded signal cable for
  transmittance of the output signal to the signal
  conditioner.
• Provide a separate signal conditioning circuit
  for output scaling to suitable A/D converter
  range in display block.

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Block Breakdown
4-30 VDC input from power supply
AD590 Temperature Sensor Probe
Interface with display A/D converter
Signal Conditioner
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Block Detail Design

• AD590M measures temperature in K to 0.5 degrees
  accuracy.
• LM741 and LM1458 Dual Operational Amplifiers
  serve as signal amplification devices from uA to
  mA needed.
• AD580 high precision voltage comparator serves as
  error correction tool.

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Signal Conditioning Block

• Owner Anthony Futterer

The purpose of the signal conditioner is to
convert the load cell output signal to a usable
A/D converter signal amplitude for the display
block.
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Performance Requirements

• Provide an input port for the signal from the
  load cell.
• Provide an inline shielded signal cable for
  transmittance of the output signal to the
  display.
• Provide a separate signal conditioning circuit
  for output scaling to suitable A/D converter
  range in display block.

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Block Signal Table

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Block Breakdown
24 VDC input from power supply
Load Cell Input Connector
Interface with display A/D converter
Signal Conditioning Circuitry
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Block Detail Design

• Takes in Load Cell Signal.
• LM741 and LM1458 Dual Operational Amplifiers
  serve as signal amplification devices from uA to
  mA needed.
• AD580 high precision voltage comparator serves as
  error correction tool.

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Reliability Assessment, Growth (Sig-Cond/Temp
Sensor Block)

• The Team Used the Method B reliability Database
• Total from my combined blocks spreadsheet was
  343.2078566
• Total MTBF was therefore 0.002393
• The dominant parts of unreliability was the
  MC1403U Precision Serial Voltage Reference IC
• This could be improved by using the AD580 Voltage
  Reference IC or a similar part with a higher
  operating temperature than the MC1403U.

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Keypad Block

• Owner Brandon Bartell

• The main purpose of the keypad block is to
  provide a security feature by making the user
  enter a 4digit-code. When the code is entered
  the user will be allowed to pour their drink.
• Implementation of a controlling device will also
  provide metered pouring to either 12 or 16 ounce
  depending on user selection.

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Block Detail Design
Anticipated appearance of actual keypad
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Block Breakdown
In from power supply block
Control/Timer
Power
Interface with solenoid block
User interface (Keys)
Out to solenoid block
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Block to Block Interface

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Block Detail Design

• The EEPROM memory protects the stored data in
  case of power failure.
• Over 100 million combinations are possible for
  the user codes.
• Two other codes can be used to allow user to get
  a metered pour of 12 or 16 ounces.
• Two separate relay outputs.
• Audible key operation - optional

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Performance requirements for keypad block
Accuracy -Within .1 to .2 User
Indicators -Indicator Parameter 3
LEDs. -Applicable User Interface Type Analog
3x4 keypad matrix -Mechanical Interfaces
Interface with solenoid block via
relay signal.
-Analog Input Signal Frequency 67Hz. -Power
Signal Input Frequency 57 63Hz.
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Standard requirements for keypad block

• Min. Operational Ambient Temperature Range 0 to
  50 degree Celsius.
• Min. Operational/Storage Ambient Humidity Range
  100 Rh.
• Min. Storage Ambient Temperature Range -50 to 65
  degree Celsius.
• Applicable Safety Standards UL 873.
• Applicable EMC Standards IEC 61000-4-11.
• Estimated Max. Production Lifetime 5 years.
• Reliability in MTBF 0.09 years.
• Service Strategy Repair.

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Safety requirements for keypad block

• Compliance with IEC61000-4-2
• Compliance with IEC61000-4-3
• Compliance with IEC61000-4-6
• Compliance with IEC61000-4-8
• Compliance CISPR11- RF Emissions

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Block Detail Design

• Specifications
• relay outputs
• output 1 5 Amp
• output 2 1 Amp, N.C. N.O. dry contacts, DC 30V
  max.
• operating voltage DC 12V (DC 10-14V)
• current drain 10 - 100mA
• duress output NPN transistor with open collector
  output, switches to ground (-) when activated,
  100mA/25V DC max.
• codes available User 1 2, Super User, Master,
  Duress and Accelerated codes
• code combinations 111111100
• dimensions 4.6" x 2.9" x 1.9"
• weight 6.5oz (net), 8.1oz (gross)

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Reliability Assessment, Growth (Keypad Block)

• Total FITS 825.2496
• MBTF 0.00121175
• Dominant unreliable parts are LM741 Op-Amp and
  Switches
• Obvious resolution for unreliable parts is to
  make the switches waterproof as well as dustproof
  and of a better quality to increase reliability
  factors as well as better component selection on
  the Op-Amp.

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Power Supply Block

• Owner Hector Gomez

The purpose of the power supply is to supply
energy to all the blocks. It will also provide
overload protection in case of short circuit in
the product.
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Performance Requirements

• To deliver power at /- 5 of required voltages
  with low noise.
• To supply enough current for all the blocks
• To turn off entire blocks with a toggle switch

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Power Supply Block to Block Interface
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Block Breakdown

Temperature sensor

Keypad/Security
Power Supply AC/DC 120AC 5DC/24DC 3.0 Amp
120 AC 60HZ
Scale
Signal conditioner
Display
Flow solenoid
Hector
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Block Detail Design

• Transformer steps down voltage
• Diode Bridge does the conversion of AC to DC
  Voltage with 3amps rated diodes and 10 ripple
• First phase capacitor used to eliminate
  transients and makes voltage linear
• LM317T regulates voltage and offers current
  limiting in case of failures in the system.

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Block Detail Design

• Specifications
• operating voltage 120VAC /- 10
• 60 Hz Input /- 3 Hz
• Output Voltage DC 5-12V
• Output Current 3A
• User Interfaces Toggle switch (to turn off
  power)
• dimensions 8 X 10
• weight 18oz (net), 8.1oz (gross)

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Basic Operation

• Transformer Rectifier Smoothing Regulator

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Transformer
turns ratio   Vp    Np    and    power out  power in   
turns ratio   Vs    Ns    and    Vs  Is  Vp  Ip
Vp primary (input) voltageNp number of turns on primary coilIp   primary (input) current     Vs secondary (output) voltageNs number of turns on secondary coilIs   secondary (output) current
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Bridge Rectifier
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Output with a Small Ripple
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Complete Rectification
10 ripple, C (5 X I) / Vs X f C  smoothing
capacitance in farads (F)Io  output current
from the supply in amps (A)Vs supply voltage
in volts (V), this is the peak value of the
unsmoothed DCf    frequency of the AC supply
in hertz (Hz)
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Reliability Analysis of Power Supply

• Total FITS 186.65.
• MTBF 1/186.65 .005
• Dominant part for unreliability is the switch
  with lambda 44.
• Elimination of mechanical switch will reduce
  considerable the lambda factor.

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Display Block

• Owner Sneha Juvekar

The purpose of the display block is to convert
the analog signal from the signal conditioning
block to the digital signal and to display either
the temperature inside the kegerator in degree
Celsius or weight of the tank in pounds on the 7
segment LEDs and to eliminate the switch bounce
caused by user interface.
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Performance Requirement for Display

• User Inputs
• -Input 0 to 5VDC Analog signal from signal
  conditioning block and 5 to 6VDC from power
  supply.
• -Indicator Viewing Environment Bright light.
• -Switch Type SPST (Mechanical) Switch.
• -Analog Input Signal Frequency 67Hz.
• -Analog Input Signal Impedance 800ohms.
• -Power Signal Input Frequency 57 63Hz.

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Performance Requirement for Display

• Accuracy
• -Within 1 to 5
• User Indicators
• -Indicator Parameter 4 7-segment LEDs.
• -Binary Indicator Technology LED.
• -Analog Indicator Technology Filament.
• -Numeric Indicator Technology 7segment LED.
• -Applicable User Interface Type Analog Switch
• -Mechanical Interfaces PCB

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Performance Requirement for Display

• Operation Modes
• - Applicable Power Input TypeDC.
• -Functional Mode Normal.
• -Functional Features Secure
• -Functional Threshold voltage for a CMOS
  Hysteresis gate 0.45 to 0.55V
• Electrical Interfaces
• -Signal Type Analog.
• -Signal Direction Input.
• Mechanical Interfaces
• -Mechanical Interfaces PCB.
• Overall Product Association
• -Required to convert the analog signal
  into a readable measurement of either Temperature
  or Weight.

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Standard Requirement for Display

• Max. Material Cost 149.52
• Max. Manufacturing Cost 22.50
• Max. Display Volume 2.7 cm3
• Max. Display Mass 7lbs.
• Total Components required 17
• Total PCB Area 103.32
• Input Voltage Requirements 5 to 6VDC
• Input Current Requirements 200mA.
• Max. Total DC Power 7.5Watts

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Standard Requirement for Display

• Min. Operational Ambient Temperature Range 0 to
  32 degree Celsius.
• Min. Operational/Storage Ambient Humidity Range
  100 Rh.
• Min. Storage Ambient Temperature Range -50 to 65
  degree Celsius.
• Applicable Safety Standards UL 873.
• Applicable EMC Standards IEC 61000-4-11.
• Estimated Max. Production Lifetime 5 years.
• Reliability in MTBF 0.04 years.
• Service Strategy Repair.

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Standard Requirement for Display

• Full Warranty Period 2 years.
• Consumption Power 7.5 Watts.

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Safety Requirements for Dispaly

• Compliance with IEC61000-4-2
• Compliance with IEC61000-4-3
• Compliance with IEC61000-4-6
• Compliance with IEC61000-4-8
• Compliance with MIL-PRF-38535
• Compliance with MIL-STD-202
• Compliance with UL 1741
• Compliance CISPR11- RF Emissions

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Display Block interface
Power Signals Type Direction Voltage Voltage Range Voltage Range Freq Freq Range Freq Range V-Reg V-Ripple Current
      Nominal Min Max Nominal Min Max Max Max Max

                       
Power supply DC Power Input 6V 5V 7.5V DC N/A N/A 0.01 1.8V 1.0A
Analog Signals Type Direction Coupling Voltage Max Impedance Impedance Freq Range Freq Range Leakage
        Amplitude Min Max Min Max Max

Signal Conditioner Analog Input Direct 5.0V 800 ohm 1.2Kohm DC N/A 10pA
Signal Conditioner Analog Input Direct 5.0V 800ohms 1.2Kohms DC N/A 10pA
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Block Breakdown
Input of 5 to 6 VDC from power supply
Input analog signal from signal conditioning block



7 segment LEDs
A/D Converter
Multiplexer (CMOS Analog Switch)
Mechanical Switch
Hysteresis Buffer
Analog Debounce
User
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Block Detail Design

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Block Detail Design

• Multiplexer which is the CMOS Analog Switch
  MAX319 takes the analog input signal from the
  signal conditioning block and the output of the
  Switch is connected to A/D converter.
• Analog Switch is implemented in order to ensure
  that the switch bounce stops before the
  Hysteresis gate reaches its input threshold
  voltage.
• CMOS Hysteresis gate with a threshold voltage of
  0.45 to 0.55V in order to pull the input out of
  the threshold the first time the gate switches.
• Mechanical Switch is used to select either the
  temperature signal or weight signal as an input
  for the Multiplexer.

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Block Detail Design

• ICL7107 A/D Converter is used to take the analog
  input signal from the Multiplexer and convert it
  to digital signal which provides an input digital
  signal to the 7-segment LEDs.
• 7-segment LEDs is used to display the temperature
  and weight measurements in numbers.
• 3 rightmost LEDs display numbers from 0 to 9 and
  the leftmost LED can only display number 1 and if
  the measurement is negative, it displays a -
  sign.

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Block Detail Design

• Specifications
• Supply Voltage /-5V (Symmetrical)
• Power requirements 200mA (maximum)
• Measuring range /- 0 1.999 VDC in four
  ranges.
• Accuracy 1
• Features
• Small size.
• Low cost.
• Simple adjustment.
• Easy to read.
• Durable.

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Reliability Assessment, Growth (Display Block)

• Total FITS 27.761
• MTBF 0.036021
• Dominant part for unreliability with highest
  lamda switch
• Implementing a flip-flop instead of a mechanical
  and manual switch

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Load Cell Block

• Owner Nick Bouche

The load cell will measure the weight of the keg
and its contents. This will then be calibrated
such that the weight of the keg will be zero so
that only the contents are weighed. This weight
will then be converted to volume.
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Standard Requirements

• Compliance with IEC 60332-2-34
• Compliance with IEC 61000-4-5

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Performance Requirements

• Accurate within 0.8 lbs

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Block to Block Interface for Load Cell
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Breakdown Diagram

• Force Sensor

Power
Zero Calibration
Weight to Volume Converter
To Signal Conditioner
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Detail Design

• Force sensor will be used for measuring weight

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Solenoid Valve Block

• Owner Nick Bouche

The solenoid valve block will dispense liquid per
the users input. The user must enter in the
correct code and then select one of a number of
sizes. This block will be responsible to
dispense liquid for only as long as needed to
pour the correct amount of liquid.
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Standard Requirements

• Compliance with CSA C22.2
• Compliance with IEC 61000-4-5

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Performance Requirements

• Dispense the amount of liquid wanted using
• A known flow rate
• A timer
• User will select a position on a switch to
  determine the amount of time the valve will open
• User will push a button to open the valve for the
  select time period

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Block to Block Interface for Solenoid Valve
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Breakdown Diagram
Size 1
Size 2
Size 3
Flow Control
Password from keyboard
Power
Relay

• Solenoid Valve

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Detailed Design
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Detailed Desgin

• R1 will vary based on the users selection of
  volume of liquid to be dispense.
• R1 determines how long the signal will be 5V
  before dropping to 0V.
• R3 acts to create a voltage divider so that the
  voltage at that point is 5V so that it matches
  the input signal from the keypad.
• The switch that closes the circuit at t0 will be
  a momentary N.C. push button.
• The output from this circuit will be the input
  for the relay which will then feed power to the
  valve.

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Reliability Assessment, Growth (Solenoid Block)

• Total FITS 319.3
• MTBF 0.0031319
• Dominant part for unreliability are the relay and
  the solenoid valve.
• A relay and a solenoid valve that would have
  higher maximum rated voltage would improve the
  reliability.