final report in color

Group #15 Group Members: Nadene Crain

Kristen Ossolinski Rebecca Stock

December 13, 2014

Fall 2014

Perfect Tea Maker

Table of Contents Table of Contents………………………………………………………………………………………………………………………3 Design Summary………………………………………………………………………………………………………………….……4 System Details………………………………………………………………………………………………………………………..…6 Design Evaluation……………………………………………………………………………………………………………..……..10 Partial Parts List……………………………………………………………………………………………………………………...13 Lessons Learned……………………………………………………………………………………………………………………...14 Appendix………………………………………………………………………………………………………………………………...15

Design Summary

Group 15’s Mech 307 project’s goals were to make a perfect tea maker. The greatest

challenges with brewing the perfect tea is allowing correct steep time, having freshly boiled water

at 210 deg, and making tea that makes exactly one cup. These challenges set the design criteria for

the project. This modern tea maker was designed to blend into today’s modern urban society and

allow consumers to enjoy a cup of tea with no hassle.

The device works by an IR sensor detecting if the cup is in place or not. If the cup is not

there two LEDs will flash and end the program. If the cup is present, the start button can be

pressed and water will exit a reservoir into a water heater chamber and then dispensed into the

cup. Once the cup is filled with boiling water a mechanism will lower a tea bag into the cup and

the tea will steep for the allowed time. Once the time is up, the motor will raise the tea bag and the

tea will be ready to consume. The Perfect Tea Maker creates one cup of either herbal or black tea

at a time with no mess.

The overall design of the tea maker was formed into the letters “T”, “E” and “A” as seen in

figure 1. Each letter served an important function in the tea brewing process. The T encased all of

the manual inputs and electronics. This was designed to keep the water and electronics separate.

On the stem of the T, there is storage for an extra cup and extra tea bags, making it easy to brew

another cup. The E braces the water reservoir which connects to the heater. The heater is located

directly below the A. The A allows space for the cup, room for the tea bag to be dropped from the

top and water to be dispensed into the cup.

Figure 1: Project Structure

Water Reservoir

Hot Plate

Tea Bag Mechanism

Start Button/

Tea Selector

Tea bag Storage

LED Indicators

System Details Heater

Figure 2: Heater

Figure 2 displays the critical part of the project that heats the water. The heater only allows water to enter the cold valve and exits through the hot valve because it is a one way valve. In the process water becomes boiling hot. The bimetallic thermal cut off connecters are a mechanism that cuts the power to the heater if the heater reaches a temperature grater than 216C.

Figure 3: Power

This diagram shows the power source and relay connections for the project. As seen in the wiring

diagram, the output from the PIC turns on a transistor, which connects two 9V batteries wired in

series to ground. This allows sufficient current to flow through the relay to close the switch and

connect 120V to the heater. Once converted to 5V DC, power is provided to the components on the

breadboard through the leads shown.

Mechanism: Pulley

Figure 4: Mechanism

Figure 4 displays how the pulley mechanism works. First the motor is turned on counter clockwise, then the string passes through the pulley which then drops the tea bag strainer into the cup. Once the tea is finished brewing, the motor then runs clockwise and lifts the tea strainer. Breadboard

Figure 5: Breadboard

Figure 5 presents the breadboard of the working tea maker. It displays the actual circuit components and where they are placed.

16F88 PIC

H-‐Bridge

Transistor to turn on relay

Two 9V batteries

connected in series

9V power

5V power Capacitor to

amplify speaker

Speaker

Pulley

Tea strainer

Motor

Block Functional Diagram

Figure 6: Block Functional Diagram

Figure 6 demonstrates the logic behind the breadboard and the inputs and outputs of the system. The logic behind the functional diagram is found in the appendix.

Figure 7: IR Sensors

Figure 7 displays when the IR sensor see each other and when the signal is interrupted.

IR pair open

IR pair interrupted

Design Evaluation

There are multiple design considerations for developing a tea maker. The first is to make it

marketable. A single cup drink device is gaining popularity in todays society but a tea maker

which can boil and steep the tea for the correct time, affordable and only make a single cup is

unheard of. To keep the costs down so more consumers could enjoy a fresh cup of tea design a

simple machine. There is no reason for an over priced device with less functionality.

Output Display

A visual display is key to interact with the user and indicate how the tea maker is

functioning. An LED unit is integrated into the system to signify if a cup is present, when the tea is

brewing and when the tea is finished. When a cup is not present both of the LEDs will flash on and

off twice and end the program. This is a safety feature which prevents water to boil and dispense

with out a cup present. A LED is also indicated if the tea is actively brewing. This indicator stays

on during the entire length that the tea bag is inside the cup. This lets the user know that the tea is

still being made and should not be disturbed. The final LED indicates when the tea is completely

ready and finished brewing. When this light turns on, the tea is ready.

Audio Output

Although there is an LED which indicates visually that the tea is ready to drink the song

“I’m a little Tea Pot” if brewing black tea was also important. Since this is the modern day one

press button tea maker, the user can do other things while the tea is brewing. A song helps display

to the user that the tea finished brewing so they remember to drink the tea. The sound is loud

enough to hear across multiple rooms but not too loud and short enough not to be annoying. If the

song that plays is a melody scale, it means the tea finished brewing herbal tea. There are two

songs that indicate both tea types. The speaker is software-‐controlled with synthesized music. A

PIC sound command matches note frequencies that are set as variables, which allows the program

to read two different songs. These songs can be changed depending on the user specifications.

The volume was boosted using an amplified capacitor circuit. This provided the perfect frequency

of noise to indicate the tea is finished brewing.

Automatic Sensors

One important safety feature is to make sure the tea does not brew if there is not a cup

there. For this reason the most logical sensor selection was a photo-‐optic IR detector and emitter

pair. This automatic sensor detects if there is an obstruction between the pair. When there is

nothing blocking the pair, the emitter sends out an infrared laser light that is transformed into an

electrical current and is detached by a voltage detector. The emitter produces a certain

wavelength that when a current is applied, it is detected. IR detectors act similar to motion

detectors when the cup is in range. The signal is reflected back to the emitter and the program

signal goes high and runs the program.

Actuators

One important function of the tea maker was to brew tea for the correct time. To achieve

this function, an actuator two phase bipolar stepper motor was implemented. This motor could

successfully raise and lower the tea bag slow enough not to swing or splash the bag. There are

four terminals which connect the motor to an H-‐bridge. The motor provided enough torque for

the job had difficulty when wanting to run the motor both clockwise and counterclockwise. The

magnetic polarity has to change directions, which was why the H-‐bridge was necessary. By

purchasing this stepper motor, it saved on cost and provided functionality but provided a bit more

coding.

Mechanisms and Hardware

A pulley system mechanism and hardware was implement to ensure success of the tea bag

lowering from the motor as seen in figure 4. The first pulley is horizontally aligned with the exit

mode of the motor. The pulley system keeps the weight perpendicular to the motor shaft . Having

a pulley placed there made sure there were no snags in the string or that it would catch on

anything. This also allowed the tea bag to drop directly over the cup.

Another mechanism was incorporated into the heater as seen in figure2, a one way valve is

engineered into the heater to prevent boiled water to come back through the entrance tube or

reservoir. Having this mechanism allows pressure to buildup and force the water out the other

end of the tube. This design was perfect for our device and allows water to flow out and dispense

into a cup without a pump. The system is very quiet overall and space efficient.

The heater mechanism is made of aluminum tubing that is heated by nichrome wire. The

aluminum gets hot enough so that when water passes all the way through the aluminum and

arrives boiling. This boiling water is directly dripped into the cup.

Power Source

The power, figure 3, required to make each component run had different requirements. An

old phone charger provided a voltage source 110V to the heater. The heater required the most

amount of voltage to continuously heat the water and cup and it had to be a constant source. A 5V

regulator is used to convert to DC for the PIC, H-‐bridge and all other components. All of these

components do not take much to power so 5V was adequate. After multiple tests it was

determined that in order to trip the relay batteries were needed to boost to 18V. The heater is

turned on when the relay and a transistor network goes high from the PIC.

Logic, Processing, and control; and miscellaneous

The Perfect Tea Maker uses a PIC interfacing with an H-‐bridge to control bipolar stepper

motor. The programmed logic used is PIC Basic Pro to code. The actual code is located in the

appendix. The functional block diagram is found in figure 6 and the software flow chart is in the

appendix. The program is relatively simple and is found in the appendix. There is a safety feature

which will shut off the heater if it becomes too hot. Two bi-‐metallic safety shutoffs are for the

heater when it reaches 216F to prevent over heating and fire.

In todays society reduce, reuse and recycle are important and when designing for the

modern consumers they want a product that is also eco friendly. For this reason an interesting

aspect of the Perfect Tea Maker is it extremely thrifty. Many items for the project were found at

the local thrift store. These include the heater, 5V converter, warming plate, reservoir for water,

tiles, tea cup, tubing, tea storage container and the relay from a printed circuit board. Obtaining

these parts from second stores allowed the project to stay well under budget and provided instant

feedback if they were to work. The components were “upcycled” and composed a product which

is truly unique.

Partial Parts List Overall the Perfect Tea Maker was designed to meet the standards of the modern society.

The projects budget stayed under $25 which is low enough to make a profit if the tea maker was to

sell in the market. The project remained simple with an open concept and re purposed multiple

items to make the device like the flawless traditional maker but with a contemporary twist. The

interesting bill of materials is found in Table 1.

Table 1: Partial Bill of Materials

Item # Part Description Model # Where Purchased Quantity Cost 1.1 Bipolar Stepper Motor ST-‐PM35-‐15-‐11C SparkFun.com 1 $ 6.95

1.2 Infrared Emitter and Detector LTE-‐302 SparkFun.com 1 $ 1.95

1.3 Tea Ball Infuser 922TB120 Webstaurant Store 1 $ 1.49 1.4 Round Magnet Speaker B008DS1UBO Amazon.com 1 $ 4.50

1.5 Heating Element-‐from Mr. Coffee N/A ArcWay Thrift 1 $ 2.50

1.6 AC-‐DC Converter-‐from phone charger N/A ArcWay Thrift 1 $ 1.00

1.7 H-‐bridge SN754410 SparkFun.com 1 $ 2.35

Lessons Learned

The Mech 307 project provided multiple learning experiences throughout the semester.

One of the largest lessons is in regards to the electronics. For all of us, it was our first time

programming. A whole programming language was learned and mastered. Our group found that

everything would be working incredibly well then suddenly one component stops working.

Electronics are bound to burn out or be improperly wired. Although this is frustrating and ate

away at our budget, there was a lot learned in the electronics. More times than not the project

would be fine just the power was never plugged in. The motto for the semester was “If it works

don’t fix it”. In addition, when ordering parts it is a good idea to order two quantities of every

component. One thing might go wrong and rather than waiting a week for the part to come in, you

already have it. This would is our lesson learned and hope future teams take replacements into

account when thinking about future projects with a strict time schedule.

Appendix

Table 2: I/O List

Figure 8: Software Flow Chart

Figure 9: Wiring Diagram

Tea Maker Program: 'define vaiables start Var PORTB.0 'start brewing button heater Var PORTA.0 'water heater motor Var PORTA.1 'stepper motor black Var PORTB.1 'black tea button brew Var PORTA.2 'brewing LED speaker Var PORTA.3 'finished brewing sound done Var PORTA.4 'finished brewing LED cup Var PORTB.2 'sensor incating if cup is in place one var PORTB.7 two var PORTB.6 three var PORTB.5 four var PORTB.4 i var byte

'musical note variables ah con 118 bh con 119 ch con 120 dh con 121 a con 108 b con 110 c con 112 d con 114 e con 115 f con 116 g con 117 'initialize I/0 pins TRISA = %0000 TRISB = %00001111 'staring conditions low heater low one low two low three low four low brew low speaker low done main_loop: IF (start == 0) then goto main_loop 'wait for start button to be pressed else goto cup_check endif cup_check:

If (cup = 0) Then 'check if cup is in place. If not, blink both LEDs 2 times. low heater 'if heater is on, turn off low done 'if done light is on, turn off high done high brew pause 600 low done low brew pause 300 high done high brew pause 600 low done low brew goto main_loop 'return to main loop else goto run 'When start is pushed and cup is in place run. Endif run: high heater 'turn on heater pause 6000 'wait for water to boil pause 6000 pause 6000 pause 6000 gosub lower 'turn on motor to lower tea high brew 'turn on brewing led low heater 'turn off heater If (black = 0) Then pause 6000 pause 6000 pause 6000 pause 6000

pause 6000 'brew herbal tea for 5 min low brew 'turn off brewing light gosub lift 'turn on motor to raise tea high done 'turn on done light sound speaker,

[c,20,e,20,d,20,f,20,e,20,g,20,f,20,ah,20,g,20,bh,20,ah,20,bh,20,ch,40,c,40] pause 150 'sound finished else goto Black_Loop endif Goto main_Loop lift: For i = 1 To 20 low one: high two: low three: high four pause 50 low one: high two: high three: low four pause 50 high one: low two: high three: low four pause 50 high one: low two: low three: high four pause 50 Next i i = 1 return lower: for i = 1 to 20 high one: low two: low three: high four pause 50 high one: low two: high three: high four pause 50 low one: high two: high three: low four pause 50 low one: high two: low three: high four

pause 50 next i return Black_Loop: pause 6000 pause 6000 pause 6000 'brew black tea for 3 min low brew 'turn off brewing light gosub lift high done 'turn on done light sound speaker, [c,30,d,10,e,30,f,10,g,40,ch,40,ah,40,ch,40,g,70] pause 10 sound speaker, [f,40,f,30,f,10,e,40,e,40,d,40,d,30,d,10,c,70] pause 10 sound speaker, [c,30,d,10,e,30,f,10,g,40,ch,40,ah,40,ch,40,g,70] pause 10 sound speaker, [ch,60,ah,10,g,40,f,40,e,40,d,40,c,120] pause 150 'sound finished Goto main_loop End

final report in color

Documents

page8 mechanism

power capacitorto

pulley figure4

eandaassee figure1

page5 figure1

t directlybelowthea

makin anothercup

hav at210deg