Intro

There are a number of good and decent circuit simulation and design programs out there that are either free or reasonably priced. The following is a curated selection of programs that we use at Wilderness Labs for various things.

Fritzing

Fritzing in a free, open-source application that is easy to use and is good for creating schematic designs and breadboard views from those schematics. It also has some printed-circuit-board (PCB) design functionality, though it’s best for simple PCBs. It’s available for both Windows and Mac.

Here’s a screenshot showing the schematic view:

Screenshot of the Fritzing software showing a Netduino sample schematic view where components are represented as boxes with input and output pins.
Screenshot of the Fritzing software showing a Netduino sample schematic view where components are represented as boxes with input and output pins.

And the breadboard view of the same schematic:

Screenshot of the Fritzing software showing a Netduino sample breadboard view where components are represented as visual components connected to each other as you would build them.
Screenshot of the Fritzing software showing a Netduino sample breadboard view where components are represented as visual components connected to each other as you would build them.

Much of the circuits created in this tutorial are done in Fritzing.

iCircuit

iCircuit is a commercial, yet affordable (USD$5 - $10), and very powerful real time circuit simulator. It’s available for iOS, Android, Windows Phone, Mac, and Windows, and has a lot of great example circuits. It’s great for doing all the circuit math for you and actually model how a circuit works in real time. The following screenshot is a circuit that has a 555 timer changing a 7-segment LED, and what’s neat about it, is that you can watch the 7-segment LED go through numbers in the app!

Screenshot of iCircuit showing a sample simulation schematic of driving a 7-segment LED from a 5-5-5 timer.
Screenshot of iCircuit showing a sample simulation schematic of driving a 7-segment LED from a 5-5-5 timer.

Eagle CAD

Eagle CAD is a semi-professional schematic and PCB design program that’s published by AutoDesk. It’s a quality piece of software with a decent, user-friendly UX. There is a free version, but to create anything more than the most simple of boards (more than 2 layers), it’s at least USD$100/year, and to do anything more than 4 layers (which is needed for a lot of modern designs), it’s USD$500/year. It’s available for Windows, Mac, and Linux.

SparkFun and Adafruit publish most of their open-source designs in eagle, so it’s a good choice for most connected things designs.

The following screenshot shows the schematic view in Eagle:

Screenshot of Eagle CAD software showing a sample schematics view.
Screenshot of Eagle CAD software showing a sample schematics view.

And the PCB editor looks like the following:

Screenshot of Eagle CAD software showing a sample PCB editor view with overlapping traces of various thicknesses, represented by different colors.
Screenshot of Eagle CAD software showing a sample PCB editor view with overlapping traces of various thicknesses, represented by different colors.

KiCAD

KiCad is a free, open-source, professional grade schematic and PCB editor. It does unlimited layers and complexity of designs, but the UX is atrocious. It’s available for Windows, Mac, and Linux.

The following is a screenshot of the schematic editor:

Screenshot of KiCad showing a sample shcematics view.
Screenshot of KiCad showing a sample shcematics view.

And the PCB editor looks like the following:

Screenshot of KiCad showing a sample PCB editor view.
Screenshot of KiCad showing a sample PCB editor view.

Others

There are countless other schematic and PCB design programs, both free and professional, some are even online. The higher-end professional programs do a lot more, but they run a minimum of USD$10,000/year or even USD$50,000/year and more, depending on the features. I’ve also used most of them, and while they may do things that the free and prosumer software I listed above don’t, I’ve yet to find one that has a user-friendly UX. Most of the other free and low-cost schematic and PCB design software is not very good, or is uses very proprietary file formats.

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