Mr Cope Temperature Sensitive Alarm Situation Design Brief Task Analysis In the interest of being energy efficient we are constantly reminded to use less energy by keeping fridges, freezers and even our homes at the correct temperature. It is difficult to know exactly the temperature the appliance is at. Design and make a thermometer that can be used within the home to check the energy efficiency of household products. And the accuracy of their performance, which I turn means how much money is spent on Who will use it? Where will it go? What power supply? What range will it need to cover? What colour should it be? Why is there a need for it? How will it turn on and off? Will it have an audible alarm? How big will it be? How will it save energy? How much will it cost to make? How much will I sell it for? Are there existing designs it competes with? What materials will it be made from? 22.05.13 Clear acrylic cost? Bolt costs? How accurate does it need to be? How can I makes sure it is safe? What else can it be used to do? How will I test / calibrate it? Will it need a probe?
Transcript
Mr Cope Temperature Sensitive Alarm
Situation
Design Brief
Task AnalysisIn the interest of being energy efficient we are constantly reminded to use less energy by keeping fridges, freezers and even our homes at the correct temperature. It is difficult to know exactly the temperature the appliance is at.
Design and make a thermometer that can be used within the home to check the energy efficiency of household products. And the accuracy of their performance, which I turn means how much money is spent on bills.
Who will use it?Where will it go?What power supply?What range will it need to cover?What colour should it be?Why is there a need for it?How will it turn on and off?Will it have an audible alarm?How big will it be?How will it save energy?How much will it cost to make?How much will I sell it for?Are there existing designs it competes with?What materials will it be made from?
22.05.13 Clear acrylic cost? Bolt costs?How accurate does it need to be?How can I makes sure it is safe?What else can it be used to do?How will I test / calibrate it?Will it need a probe?
Mr Cope Temperature Sensitive Alarm
Research PlanI shall research:1. The components needed2. The target customer3. The best material for the case4. What temperature range?5. Which appliances it can be used with?6. What competing products are there?
Target CustomerAge: 25 -40Job: ProfessionalReason for wanting the product: As an educated person I realise the need for us all to take responsibility for the long term survival of the planet and as such we all have a duty to ensure that finite resources are not wasted. I try to wash clothes at a lower temperature, keep the house thermostat set to as low a temperature as possible and generally use the minimal electricity as possible.
This is a energy rating sticker that goes on an appliance. Does the rating depend upon the temperature it operates at?
Mr Cope Temperature Sensitive Alarm
Fridge & Freezer Thermometers
HouseThermometers
OvenThermometers Bath
Thermometers
I shall expand on my findings in the research analysis but there are a large number of opportunities for a thermometer that can check the accuracy of thermostats and temperatures in our homes. Digital, analogue and even photo-chromatic. The accuracy of these thermostats is what we base a huge amount of our energy efficiency upon. If they are out then we spend money on bills when it is not required.
This pipe thermometer makes me think I could check the temperature of the house hot water tank.
Thermo-chromatic materials.
Probe, I think a probe is a good idea as it will protect the electronic circuit from the temperature extremes I am looking to measure.
I would prefer a digital read out although the inputs has to be analogue as signal is taken from a thermistor in most of the se products.
Mr Cope Temperature Sensitive Alarm
Detachable for easy window cleaning Weather-resistant Temperature Range: -13°F to 158°F (display in Fahrenheit only) Takes 1 AAA battery Dimensions: 4″ x 3.75″ x 1.25″Cost: £8.99
This product suggests that my product should be less than £10. However this product will not be as versatile as mine and so a slight increase in price should be ok. It will only give a reading in Fahrenheit which is not suitable in the UK.
The min and max range shows the range the unit has been exposed to but I am uncertain of the value of this information.
Solar Window Thermometer, Read Your Outdoor Temperature Inside, Large Digits For Great Viewing, Self Adhesive, Displays Current Outside Temperature, Current Time & The Minimum/Maximum Temperature Values, Automatically Resets Hi's & Lo's In The Morning & Evening, Weather Resistant Casing & Detachable For Window Cleaning, Current Outdoor Temperature Digits Are Almost 1.5" Tall, Features Solar Panel For Recharging LCD Backlight For Night-time Viewing.
Mr Cope Temperature Sensitive Alarm
Materials and ConstructionIn school we use thermo plastics which are good for reshaping using heat. I like the look a of a vacuum formed case but like the accuracy of the laser cutter for battery access. I like this see
through acrylic case but it means the insides need to be very tidy! What cost is clear acrylic and those cool bolts?
Answer: A4 = £3.49 and bolts M4 x 60 = £1.53 each!
Mr Cope Temperature Sensitive Alarm
ComponentsThese are NTC Thermistors. NTC means Negative Thermal Coefficient and basically means that they have a lower resistance in higher temperatures. These green and black ones are bead type and cheap at 14.2p each but they are inaccurate, 10% variation in resistance
Inputs
This is an Ultra This Flexible Thermistor, these have very quick response times. £1.02 each. They are more accurate at 1%, operating at -50 to 125 °C.
This graph shows a straight line correlation between temperature and resistance. This is useful as it means I only need to calibrate a few temperatures and I can plot the rest of the temperature to score ratios.
Mr Cope Temperature Sensitive Alarm
ComponentsProcess
I feel that I am probably going to use a PIC to process the information that comes from the input. It will give me more output opportunities, increased accuracy and the chance to calibrate it before Evaluation. Whilst a C08 might do the job it depends upon the number of inputs, out puts and modes I require. The C08 will give me the chance to have one input and then three outputs.
The Genie C20 will allow me a greater number of inputs and outputs. Maybe too many and too expensive. I need to discover what number of modes and outputs I shall use. I feel certain I shall be using only one input, the flexible thermistor.
Mr Cope Temperature Sensitive Alarm
ComponentsOutputs
LEDs can be used with a written description beside them to explain what they are indicating. Low current and therefore low energy use (little battery drain), they are cheap and run around 20mA
The LCD display is easy to use and can be very informative. It is however expensive at around £12 each
7 Segment Displays can be used to show text or numbers but the way of driving them is difficult to develop a full solution.
A buzzer is unlikely to give a detailed set of information but can be used to give an audible warning if the extremes of temperature have been reached.
Mr Cope Temperature Sensitive Alarm
Email to ZanussiGood Morning,I am an Electronics teacher at Bideford College in North Devon. I plan to produce a product, in conjunction with my Year 11 students, that can be used to check the efficiency of domestic appliances. The idea is to produce a thermometer that can quickly identify if a product (fridge, freezer, oven, washing machine and dishwasher) is working at the optimum temperature. I hoped you might be able to give me the optimum temperature range for a fridge, freezer and washing machine to work at. I hope the product will be able to identify the accuracy of the appliances thermostat where it has "setable" temperature.
Thank you for your help.
Rod Cope
Mr Cope Temperature Sensitive Alarm
What temperature range?At this stage the exact range I will measuring is not identified. This will depend upon the modeling and testing of components I produce.
Mr Cope Temperature Sensitive Alarm
Research AnalysisExisting Designs: This has shown me that there are a huge range of thermometers available, analogue, digital and photo-chromatic. There is clearly a need, it could be that one design would be able to do all appliances and scenarios but it would be difficult. For some situations (Oven and Freezer) a probe would be necessary. I need to find what temperatures ranges are required for different appliances and scenarios.
Target Customer: There is a need for my product but it is quite specific. There is a need for environmentally conscientious people, and those who wish to save money on bills, to have a thermometer that is accurate and can tell if house hold appliances are working at the optimal temperature.
Materials: The clear acrylic is too expensive and bolts are even more. I think I should go with a slightly curvy High Impact Polystyrene, vacuum formed case but produce a laser cut sliding battery access.
Components: Inputs has to be the thermistor, there is no obvious alternative. The process could be an transistor, op amp or Programmable Interface Controller (PIC). The LCD display is a popular output but maybe too expensive.
Temperature Range and Email to a Company have not been fruitful yet.
Currently the ideal solution would be a thermistor driving a PIC which in turn drives an LCD. This would be housed in an acrylic laser cut casing but the cots of this solution is prohibitive.
Mr Cope Temperature Sensitive Alarm
Specification v11. My design will have a 6v supply2. My design will have a thermistor.3. My design will be sensitive to a range of temperatures from -10 degrees to +65
degrees.4. My design will have a probe5. My design will switch off when not use6. My design will have an output that allows easy reading.7. My design will have vacuum formed front but a laser cut back to allow battery
