What is Schematic Design?

Schematic design plays a key role in the development and creation of electrical devices.

Put simply, a schematic drawing boils something down to its component parts in a format that is as easy to read as possible.

The famous map of the London Underground is an everyday example of schematic design. The stations are dotted equidistant along lines that either travel straight or at 45-degree angles.

This may not accurately reflect the gaps between each stop or the twisting nature of the Tube. But it gives passengers a snapshot of where they are and how to get to where they need to be.

This is the essence of schematics and in this blog, we will discuss the role that schematics plays in different fields. We will also look at how you can use DesignSpark's software to get the most out of your schematics in your next project.

What is electronic schematic diagram drawing?

Schematic drawings display the building blocks of electronics – resistors, capacitors, transistors, and more. It is a visual code that lets you understand how an electronic circuit works without getting bogged down in details.

Schematics come in all shapes and sizes. It can represent a basic doorbell circuit or the intricate workings of a computer motherboard. The level of detail depends on the purpose and complexity of the system.

Unlike photos or pictorial drawings, schematic designs use standard symbols that are easy to understand. For example, resistors are typically represented by zigzag lines and diodes by an arrow. These symbols make schematics universal.

A good schematic drawing is neat and well-organised, consistently using the correct symbols. Think of it as a technical sketch, where every line and symbol has a meaning. Thankfully, there are software tools and online resources to help you get started, along with libraries of standardised symbols.

Schematic design symbols

While electronic schematics offer a clear picture of a circuit's design, fully understanding the symbols is crucial to being able to work successfully. The two most common standards are IEC 60617 and IEEE 315, the latter approved by the American National Standards Institute (ANSI).

• IEC 60617: This international standard, also known as BS 3939 in the UK, is widely used globally and covers a vast range of electrical and electronic components. Think of it as the universal dictionary for schematic symbols.
• IEEE 315: This standard focuses specifically on North American practices and complements IEC 60617.
• However, depending on the nature of your project, your schematic symbols may fall outside of these two common standards.
• Company-specific symbols: Some companies or organisations might have their internal symbol libraries for specific components or design practices. These usually align with existing standards but offer additional details.
• Custom symbols: For unique components or special functionalities, engineers can create custom symbols to accurately represent their behaviour. However, proper documentation is crucial to ensure clarity for others interpreting the schematic.
• When designing a schematic, there are several factors to consider when opting for a standard of symbols.
• Target audience: If your circuit is intended for international use, adhering to IEC 60617 is a safe bet. For North American projects, IEEE 315 might be more common.
• Industry context: If your circuit falls within a specific domain like industrial automation or military, using the relevant standard such as IEC 61131-3 or MIL-STD-806B ensures consistency within that field.
• Company guidelines: Check if your company has established internal symbol libraries or preferred standards.

How do I design schematics for PCB?

Printed circuit boards (PCBs) provide a base for all components that make electronic devices work. Whether a single-board PCB or one made up of multiple layers, a well-crafted schematic design can help you consistently create PCBs. This is ideal if you are looking to scale up your project in the future.

Creating a PCB schematic – and ultimately the PCB itself – can be broken down into three key processes.

Circuit schematic design

• Define your circuit: Quite simply, understand what your circuit is designed to do. Is it an amplifier, a sensor, or something more complex?
• Break it down: Divide your circuit into functional blocks (power supply, input capture, output processing). This makes things easier to manage.
• Gather your tools: Choose schematic drawing software or even a good old pen and paper! Research and understand the standard symbols for each component you'll use.

Creating your PCB schematic design

• Place your components: Add each component symbol onto your schematic, following the functional blocks you've previously defined.
• Connect the dots: Use straight lines to represent the electrical connections between components.
• Label everything: Clearly label each component with a reference code. For example, if your circuit includes multiple resistors, ensure you have them correctly listed in the schematic. This helps identify and manage them during PCB layout and assembly.
• Check… and check again: Go over your schematic for errors and inconsistencies. Many PCB software platforms include design rules checkers to catch certain mistakes. Remember, a well-designed schematic now saves time and frustration later!

From schematic design to working PCB

• Layout software: Once your schematic is finalised, export it to PCB layout software. This translates your schematic connections into the physical layout of copper tracks and components on the PCB.
• Accurate footprints: Each component has a "footprint" defining its size and pin layout. Symmetry and space are crucial when plotting these footprints, with too little – and sometimes too much – space being left on the board potentially opening the door for operability issues further down the line.

What are the benefits of using schematic drawing software?

• Clarity: Schematics focus on essential connections and components, ignoring the physical layout (which can be messy in real circuits). Use it as a roadmap instead of a street-level view, showing you each component and how they should be connected.
• Troubleshooting: If something goes wrong, schematics help you pinpoint the affected part of a circuit quickly, saving you time and frustration. It can also help in the development phase of new products and processes, allowing sections of a circuit to be verified in batches. With a DesignSpark subscription, you can access our circuit simulator to analyse the strength of your designs.
• Documentation: Schematics function as blueprints for building, repairing, and modifying circuits. If a system requires an upgrade or patch, the schematic drawing provides a foundation for any improvements to be built upon.
• Universality: Anyone familiar with the symbols can understand a schematic, regardless of language or location. This breaks down barriers and can make it easier to tap into the knowledge of experts whom you might otherwise struggle to communicate with.

Why choose DesignSpark for schematic drawing?

• Unlimited schematic sheets: We place zero limits on the number of schematic sheets you can create using the DesignSpark platform. We've got you covered whether you are making a simple, single-layer PCB or something much more complex.
• Flexible subscriptions: We offer three subscription tiers to customers to help design and create PCBs. Our free Explorer plan allows you to work with an unlimited number of PCB layers as well as schematic sheets.

We also offer two paid plans which include extra installed copies. Creator provides you with an integrated SnapEDA CAD library and advanced design rule checking. Our premium Engineer plan adds advanced features such as hierarchical schematic designs, blind and buried vias, and IPC-2581 output.

Check out our subscriptions page for the full details.

• Detailed BOM: Your bill of materials will list all parts, items and assemblies included in your schematic design. Then it is up to you if you want to complete your purchase with us or take the specification elsewhere.
• Ease of use: Not a CAD expert? Don't worry. We've designed our system to be as intuitive as can be so it's simple to create schematic drawings and get PCBs from them. If you run into any trouble, our comprehensive library of tutorial videos can help or reach out to our experts for help.
• Extensive library: Our ready-to-use libraries include a huge number of schematic designs, symbols and footprints. Or if you know your requirements already, you can start from scratch.

Get schematic drawing software with DesignSpark

Sign up for a free DesignSpark and you'll have instant access to create an unlimited number of schematic drawings for your projects. Sign up today for a DesignSpark subscription and start making the most of your schematic designs with the following programs:

• DesignSpark PCB: With vast libraries of symbols available and unlimited schematic space, you can easily create PCBs of vast scales in large numbers.
• DesignSpark Circuit Simulator: If you want to check whether your schematic drawing will make sense in the real world, this useful program lets you check how it will run in real applications and throws up any red flags before you go to production.
• DesignSpark Mechanical: Once the schematics check out, create 3D drawings in incredible detail, so you are ready to get to grips with your next product or project.

If you have any questions about our software suite or our subscription plans, browse our support centre for more information.