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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 Signal Conditioner Power Supply 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: 10°C to 32.22°C Operating Humidity Range: 0-100% Non condensing Operating Altitude Range: -300ft to 15,000ft Storage Temperature Range: -50°C to 65°C 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 : Limitation of voltage fluctuations and flicker in low-voltage supplies <16A Required because a low end voltage flicker could damage the compressor IEC : Surge Immunity tests Required because the microcontroller and other components need to be protected from potential power surges IEC : 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 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
Name Block Area (cm2) Total PCB Area (cm2) PCB Substrate Type Comp Attachment Socketed Components Types of Connectors Nick 72 65 Plastic, pads, buses Solder Relay, resistors, LEDs IEC, Circular, PCB Mount Hector 204 194 Diodes, resistors, capacitors, etc. IEC, PCB mount Sneha 105 92 ICs, LEDs IEC, PCB Mount Anthony 81 66 ICs, Relays Brandon 112 101 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 Estimated vs 400 availability. $ 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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Interface with display
Block Breakdown 4-30 VDC input from power supply AD590 Temperature Sensor Probe Signal Conditioner Interface with display A/D converter
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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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Interface with display
Block Breakdown 24 VDC input from power supply Load Cell Input Connector Signal Conditioning Circuitry Interface with display A/D converter
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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 Total MTBF was therefore 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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Owner: Brandon Bartell
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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Interface with solenoid block
Block Breakdown In from power supply block Control/Timer Power User interface (Keys) Interface with solenoid block 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 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 IEC Compliance with IEC Compliance with IEC Compliance with IEC 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: mA 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: 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 FIT’S = MBTF = 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
60HZ Power Supply AC/DC 120AC 5DC/24DC 3.0 Amp 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 Vs Ns
= Np and power out = power in Vs Ns Vs × Is = Vp × Ip Vp = primary (input) voltage Np = number of turns on primary coil Ip = primary (input) current Vs = secondary (output) voltage Ns = number of turns on secondary coil Is = 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 DC f = frequency of the AC supply in hertz (Hz)
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Reliability Analysis of Power Supply
Total FIT’S : 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: 7–segment LED. -Applicable User Interface Type: Analog Switch -Mechanical Interfaces: PCB
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Performance Requirement for Display
Operation Modes: - Applicable Power Input Type:DC. -Functional Mode: Normal. -Functional Features: Secure -Functional Threshold voltage for a CMOS Hysteresis gate: 0.45 to V 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: 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 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 IEC Compliance with IEC Compliance with IEC Compliance with IEC 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 Freq Freq Range % V-Reg V-Ripple Current Nominal Min Max Power supply DC Power Input 6V 5V 7.5V DC N/A 0.01 1.8V 1.0A Analog Signals Type Direction Coupling Voltage Max Impedance Freq Range Leakage Amplitude Min Max Signal Conditioner Analog Input Direct 5.0V 800 ohm 1.2Kohm DC N/A 10pA 800ohms 1.2Kohms
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Block Breakdown 7 segment LEDs A/D Converter Multiplexer
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: Features:
Supply Voltage: +/-5V (Symmetrical) Power requirements: 200mA (maximum) Measuring range: +/- 0 – 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: MTBF: 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 Compliance with IEC
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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 Power Force Sensor 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
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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 Password from keyboard
Flow Control 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 t=0 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 FIT’S : 319.3 MTBF : 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.
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