The Door Buzzer – Introduction – Planning your project

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The Door Buzzer – Introduction – Planning your project

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Door_Buzzer

On Github MarcScott / Door_Buzzer

The Door Buzzer

Created by Marc Scott / @coding2learn using reveal.js The Door Buzzer by Marc Scott is licensed under a Creative Commons Attribution 3.0 Unported License.

CONTENTS

Introduction Planning your project Initial Circuit Ideas Transistors Circuit Design PCB Design PCB Testing and Labelling Case Design Drilling Guide Soldering Guide Assembling the Case

Introduction

You have been asked to design a device that could be hung on a bedroom door, and act as a buzzer for people to request entry to the room. It should be battery powered.

Download the portfolio template below. This will allow you to begin to collect research and plan your project.

Markdown version MS Word version

Research

You should begin by researching the products are already on the market.

Click the link below for some ideas of how to research door buzzers.

Research

Use the information you find to complete the research section of your portfolio.

Planning your project

The Plan

Engineers need to manage their projects effectively to ensure they produce a finished product on time and on budget.

Ask your project manager (teacher) when the deadline is for the project and use the list of tasks below to create a Gantt chart to help guide you throughout.

  • Door Buzzer Research
  • Transistors Background information
  • The Darlington Pair
  • Circuit Design
  • PCB Design
  • Case Design
  • Drilling the PCB
  • Soldering
  • Case Assembly

Initial Circuit Ideas

Instructions

What follows is a series of videos, detailing how the idea for the circuit was formulated.

As you watch the videos, make a few notes so you can add these details to your portfolio.

A simple circuit idea

Using a finger as a switch

Skin resistance

Simulating the skins resistance

Simulating skin resistance in Circuit Wizard

Transistors

Instructions

What follows is a series of videos, detailing how transistors can help in our circuit design.

As you watch the videos, make a few notes so you can add these details to your portfolio.

A Single Transistor

A Darlington Pair

Circuit Design

Description

The following slides detail how you should design your Door Buzzer Circuit.

The first slide will provide a description, the second and third an image and the last slide will show a video tutorial.

You should try and design your circuit first from just the description, and then scroll down to the lower slides if you get stuck.

Use a 9V battery The 9V rail should be connected to a 9V buzzer that is in series with a transistor. The Emitter of the transistor should be connected to 0V A 330Ω resistor and an LED should be parallel with the buzzer, so that they too feed into the collector of the transistor. A second transistor should be used in series with a 22kΩ resistor. The resistor should connect to the 9V rail, then to the transistor. The emitter of the transistor should feed into the base of the first transistor. The base of the second transistor should be connected to a PTM switch which is fed from the 9V rail.

Fill in the gaps Circuit

The completed circuit

The Tutorial

PCB Design

Designing the PCB

Below are a pair of diagrams showing the completed PCB. You can use these to aid you in your design of the PCB in Circuit Wizard, or skip straight to the tutorial video on the third slide.

Once you have designed the PCB, you'll need to make a few refinements. Watch the tutorial on the fourth slide to assist you in this.

Normal PCB

Real World PCB

Tutorial

Refining the PCB

Testing and Labelling the PCB

What you need to do.

Watch the videos in the next slides.

The first will explain how to test if your PCB works or not. Follow the tutorial and take screen shots for your portfolio.

The second video will show you how to label your PCB to make the soldering easier.

Testing the PCB

Labelling the PCB

Case Design

The finished product

This is a 3D render of the finished case design. It should give you some idea of what you are aiming for.

The finished 2D design

Download image

Illustrator

The following tutorials use Adobe Illustrator to design the case. You can use an alternative program if you like, but the'll be no tutorial.

To help you use illustrator, you might find this shortcut sheet helpful.

Tutorial List

Illustrator setup Drawing the base Drawing the lid Drawing the tabs Drawing the edge strip Drawing the PCB mounts 3D Visualisation

Illustrator Setup

Drawing the base

Drawing the lid

Drawing the tabs

Drawing the edge strip

Drawing the PCB Mounts

Visualising in 3D

Drilling your PCB

What you'll need to do

Clean the PCB. Drill the holes (1mm or 3mm) Take pictures for your portfolio Write about what you have achieved at this stage.

Drilling guide guide

Soldering your PCB

The finished board.

Below is an image of the soldered PCB. Use this and the videos linked on the next slide to solder the components to the board.

Components to be soldered

Soldering a resistor

BACK

Soldering a transistor

BACK

Soldering a buzzer

BACK

Soldering flying leads to an LED

BACK

Soldering an LED to a board

BACK

Soldering a battery snap

BACK

Soldering contact leads

BACK

Case Assembly

Line Bending

1 - Countersinking

2 - Inserting the Machine Screws

3 - Attaching the contact leads

4 - Securing with threaded spacer

5 - Securing the PCB

6 - Adding the LED Bezel

7 - Securing the lid

8 - The finished prototype