Marcos Garcia - mgarc67 - ECE 110

Pavan Hegde - pavanh2 - ECE 110

Project Proposal

Statement of Purpose

The goal that we have in mind is to create a light jacket that is aimed towards having people stay warm without having the need to put on multiple layers of clothing. With this invention, we can compete with other jackets in the market and provide better value with the internal heating system. Rechargeable batteries would be able to give the jacket lasting value in the long run to be able to provide efficient warmth. It will be able to be controlled using a switch and have a thermometer to show the temperature on an LCD screen display.

Background Research

The use of resistors to heat up the jacket means taking into account things such as power rating (ceiling for what the resistor can handle in terms of watts), what value resistors should be used in the circuit, and how to setup the circuit needed for it to work effectively. Power will play a large role, having to work around it and making sure it is safe enough to be in use in the jacket. The amount of power being dissipated in the circuit will be the source of heat that will spread throughout the jacket to keep the person warm, needing to use the right combination of voltage and resistance to create enough current produce the power needed.

Block Diagram/Flow Chart

System Overview 

In order to effectively monitor and control the temperature and heating of the jacket, the circuit needs input from both the environment and the user. In this circuit, the jacket temperature and user-desired temperature are measured by a thermometer and set by a 2-button system (plus an on/off button). Based on the current jacket temperature and desired temperature, the microprocessor will output a safe amount of current through the resistor network and heat the jacket and a steady rate until the desired temperature is reached. The microprocessor will also display both the user's desired temperature and actual temperature to allow easy control of the jacket.

Parts

• Digital Thermometer
• 3, Buttons
• LCD
• Resistors/Nichrome Wire
• Batteries/Power Source
• Microprocessor

Possible Challenges 

While this product could be practical and useful, because of the amount of energy required, the power source could be depleted quickly. As a result, prioritizing energy efficiency will be important. Also finding a way to deliver the required power to elements to heat up the jacket in a human-safe way may pose as a challenge since high current has the potential to cause the user harm.

References 

"Resistor Power Rating And The Power Of Resistors". Basic Electronics Tutorials. N.p., 2013. Web. 25 Sept. 2016.

Olson, Walter H. "Electrical Safety". N.p. Web. 25 Sept. 2016.

Relevant Links: 

http://www.hotwatt.com/

http://www.coolpolymers.com/heattrans1.html

http://www.carbonheater.us/temperature.htm

https://www.sparkfun.com/products/245 (Possible Thermometer)

Weekly Overview

Monday, Oct. 3, 2016

Accomplished: Researched possible parts and methods to heat clothing safely and effectively. Looked into thermometers, displays and user input. 

Goals: Finalize list of parts, create a more concrete design for heating elements. Look into circuit optimization and power usage.

Monday, Oct. 10, 2016

Placed order on parts needed, did more background research on how project would work

Goals: Start prototyping when parts arrive and assemble basic design to test it out.

Monday, Oct. 17, 2016

Did basic testing, learned not to burn out resistors, more detailed schematics needed

Goals: Have transistor work next time we test the circuit, be safer with current near 500 mA

Friday, Oct. 21, 2016

Ran more tests trying to increase power output through the nichrome wire.

Goals: Run more tests and calculate optimal transistor/resistor setup and voltage input.

Monday, Oct 24, 2016

Qualitative testing of nichrome heating using 30 and 90 cm wires, looked a bit into what to cover the wire in.

Goals: Decide what type of material to cover the nichrome in, look into what the desired current/voltage combination should be.

Friday, Oct 28, 2016

Looked into pad materials, and nichrome heating in a duct tape pad

Goals: Incorporate transistor (MOSFET or BJT), thermometer, buttons, microprocessor, and at some point optimize nichrome pad

Monday, Oct 31, 2016

Set up Control Circuit and code for input. Sketched schematics for input as well.

Goals: Incorporate output circuit, test thermometer with nichrome pads and optimize heating element. Play with power.

Monday, Nov. 7, 2016

Ordered LCD, built more permanent prototype of design, Soldered Ends of Nichrome wire.

Goals: Optimize Nichrome Pads, Play with power and run tests.

Monday, Nov. 14, 2016

Made new nichrome pad, soldered ends again, improved circuit a bit.

Goals: Implement LCD into circuit.

Monday, Nov. 28, 2016

Put LCD in circuit (soldering included), wrote sample code to test it.

Goals: Debug LCD to get it to work properly, make adjustments to circuit as necessary.

Final Lab Report