Systems: How to model your concepts

• Compare designs to the brief, gather , and consider improvements.
• Create physical models to visualise and test designs, and gather .
• Refine circuit designs using computer aided design (CAD) software to optimise performance.
• Use CAD software to create efficient printed circuit board (PCB) layouts.
• Develop flowcharts for PIC (programmable interface controller) microcontrollers and test with CAD software.
• Create detailed working drawings for accurate manufacturing.

This section is relevant for students embarking on their design and manufacturing project and who are pursuing either Option A: Electronic and Microelectronic Control Systems; or Option B: Mechanical and Pneumatic Control Systems. Typically referred to as the Systems pathway.

Creating models is a valuable step in the design process, especially before you start manufacturing. Physical models, using materials like cardboard, paper, foam, or even 3D printing, allow you to visualize your design in three dimensions.

This helps you identify potential issues with the shape, size, and overall aesthetics of your product. You can also test the functionality of your design and make adjustments before moving on to the more expensive and time-consuming manufacturing stage.

Models also allow for and testing. People can interact with the physical model, providing valuable insights into how the product might be used and suggesting improvements to its design and functionality.

This iterative process of modelling and refining can lead to a more successful final product.

In addition to physical models, simulating circuits using breadboards and CAD software is also beneficial. Breadboards allow you to quickly build and test circuits with real components, helping you understand how the electronics function together.

CAD simulation software can model more complex circuits and predict their behaviour under different conditions. This can help identify potential problems and optimize the circuit design before it's ever built.

As you develop your design ideas, you can use freehand sketching, CAD software, or a combination of both. Freehand sketching is great for quickly getting ideas down on paper, while CAD software allows for more precise and detailed drawings.

CAD software can be used to model the design of a product in 3D, allowing you to visualize it from all angles and make changes easily. You can also use CAD to create simulations and test different materials and manufacturing processes. This can help you identify potential problems early on and make sure your product is designed for manufacture.

The next stage in developing your system is perfecting the circuit design. Start by revisiting the circuit ideas you generated during the concept stage. Analyse each one, identifying what works well and what could be improved. This evaluation will help you develop those initial concepts into a fully functional final circuit.

, using the correct circuit symbols is crucial throughout this process, as it ensures your designs are clear and easy to understand.

CAD simulation software is important for refining your circuit design. It allows you to model and test your circuit in a virtual environment, helping you identify any potential issues and optimize performance before you start physically building it. By experimenting with different components and configurations in the simulation, you can ensure your final circuit design is robust, efficient, and meets all the requirements of your system.

The next crucial step is transforming your circuit design into a printed circuit board (PCB) layout. This stage bridges the gap between your theoretical circuit and the final, manufactured product. CAD software proves invaluable here, offering tools to convert your circuit diagram directly into a PCB design or allowing you to create a custom layout from scratch.

As you design your PCB, carefully consider the placement of key elements like the power supply, inputs, process components, and outputs. Aim for a compact and efficient layout, ensuring the PCB will fit seamlessly into your final product. Always refer back to your design specification to ensure your PCB design aligns with the overall product requirements.

If using a PIC as the process in the final circuit and PCB, then a fully functional flowchart will be needed to program the PIC.

The final stage of flowchart development involves creating a comprehensive program that controls your circuit's behaviour and brings your product to life. During the initial design phases, you likely created simpler flowcharts to test basic functionality. Now, it's time to expand those flowcharts, using a full range of symbols to define every step and decision your circuit needs to make.

Think of this flowchart as the "brain" of your circuit, guiding its operation and ensuring it performs its intended tasks within the final product. CAD simulation software plays a crucial role here, allowing you to test your flowchart and even program your PIC microcontroller directly during manufacture. This virtual testing environment helps you iron out any kinks in your program and ensures smooth operation when you move to the manufacturing stage.

Flowchart symbols

Start

• start is a cell that indicates the beginning of the flowchart program
• is needed start the program

Stop

• stop is a cell that signifies the end of the flowchart
• if used, the circuit would need reset to allow the program to restart again

Output

• output is a cell that sends a signal to an output device to tell it to turn on or off
• activates devices like LEDs, buzzers, or motors

Wait

• wait is a cell that pauses the program for a specified amount of time
• delays actions to allow for timing control

Decision

• decision is a cell that makes a choice based on a condition
• directs the flowchart to different paths based on true or false conditions
• example: has a push to make (PTM) switch been pressed? Yes or no?

Compare

• compare is a cell that checks if a specific condition is met by comparing two values
• directs the flowchart based on whether the condition is true or false
• example: is the temperature being read by a thermistor above 27 degrees Celsius?

Design and development involves creating working drawings and parts lists to enable a third party to manufacture the design. Working drawings are sent from a designer to a manufacturer to enable them to build a product.

Bill of materials

The list of all the parts, materials, and instructions required to make a product

Orthographic projections are working drawings in either a first or third angle projection and show each side of a design. They are used to show an object from every angle to help manufacturers plan production.

Starting with a front view of a product, construction lines show where areas and are used to draw a side and plan (top) view, ensuring that the drawing is accurate from all angles. These drawings are to scale and must show dimensions.

Third angle projections

Third angle projection is an accurate method to produce ‘working drawings’. The position of the plan, front and side views are important in this method of drawing.

In third-angle projection, the view of a component is drawn next to where the view was taken.

What you see from the right would be drawn on the right and what you see from looking at the top will be drawn above.

First Angle Projections

In first-angle projection, the view is drawn on the other end of the component, at the opposite end from where the view was taken.

Orthographic projections have a set of standard lines to show different aspects of the diagram. These lines allow complex shapes to be drawn simply in 2D.