Electronic Circuit Simulation on macOS

If you use a Mac for your development then your circuit simulation options are fewer than for Windows, but there are options.

The genesis of this article was a design for artificial reflexes. Our usual approach is to draw up the schematic and then jump straight to breadboarding. However, there are no off the shelf designs for electronic nerves so we didn’t know exactly how we would approach this problem. We needed to play around with components using different analog conditioning blocks until we got the required output. Simulation is the perfect use case for this scenario.

It seems like anytime you want to do something new, it involves learning another software package. Electronic simulation is no different. Whatever you end up using will probably have the word “spice” in it or be a thin wrapper around one of the SPICE engines.

In the early 1970s, engineers at the University of California, Berkeley created the Simulation Program with Integrated Circuit Emphasis to solve a growing problem: circuits were becoming too complex to reason about with pencil, paper, and intuition alone. SPICE translated physical electronics into mathematics, allowing engineers to simulate voltages, currents, and transients before ever building hardware. For the first time, designers could experiment, fail, and refine safely inside a computer. There was no need to release the magic smoke as a sacrifice to the design gods. Nearly every modern circuit simulator, including LTspice, descends directly from that original idea, making SPICE one of the most influential tools ever created for electronic engineering. Wikipedia has a list of free electronic circuit simulators.

Simulation versus Breadboarding

The usual circuit development cycle is illustrated in Figure 1. It is tempting to avoid the friction of learning a new software tool and just start breadboarding with actual components and measuring the results using multimeters/oscilloscopes/etc. Where a simulator is handy is in testing your theoretical understanding of an analog circuit design. The beauty of the simulator is you have access to a wide range of free components and tools for you to test your ideas with, and no chance of starting a fire.

It’s not all sunshine and buttercups though, your simulation is only as good as the component models used. The real world is complicated and good models optimise for specific use cases. If they try to model everything it takes a long time to run the simulation. In other words, there is a tradeoff between accuracy and simulation time.

The SPICE based tools are primarily for analogue circuit simulation. At their core, SPICE simulators model circuits as systems of continuous equations, solving for voltages and currents over time. This makes them well suited to analysing resistors, capacitors, inductors, transistors, amplifiers, filters, power supplies, and messy analogue edge cases. Digital behaviour can be simulated in SPICE, but it is usually achieved by approximating logic as analogue thresholds, delays, and voltage levels rather than as discrete state machines. As digital circuits grow in complexity, there comes a point where other tools (such as hardware description languages, RTL-level simulators, and microcontroller simulators) become more appropriate than SPICE.

The Limits of Breadboarding

If you are designing based on application notes and tried and tested circuits, you can probably jump to breadboarding before laying out the PCB. Breadboarding feels honest. You can see the wires, touch the components, and convince yourself that the circuit is real in a way no schematic ever quite achieves. But breadboards are also remarkably good at hiding problems.

The first issue is that a breadboard is not electrically neutral. Every row and jumper adds resistance, capacitance, and inductance, none of which are documented and all of which vary from board to board. At low frequencies and for digital circuits this usually doesn’t matter, which is why breadboards work so well for simple experiments. As soon as signals get faster, currents get larger, or thresholds get tighter, those invisible parasitics start to dominate behaviour in ways that are hard to predict and even harder to debug.

Measurement adds another layer of distortion. Probes load the circuit. Ground clips introduce loops. Moving the scope lead changes the behaviour you are trying to observe. You end up debugging the measurement setup almost as much as the circuit itself.

Breadboards also do not scale. As circuits grow, the visual clarity that made breadboarding attractive disappears. The layout becomes dense, wires cross in every direction, and simple changes require partial reconstruction. At that point, it all starts getting too hard.

None of this makes breadboards useless. They are invaluable for quick sanity checks and for developing an intuitive feel for circuits. But they are a poor place to discover fundamental design flaws. Breadboards are best used after a circuit makes sense on paper or in simulation, not instead of it.

Simulation Rules That Don’t Exist on the Bench

One important way simulators differ from real-world circuits is that they require an explicit ground reference. Every SPICE simulation must include a ground node, usually called node 0, which serves as the mathematical reference point for all voltages. In physical circuits, ground may be implicit or floating, but in a simulator it must be defined explicitly or the circuit cannot be solved. Further, every point in a simulation schematic must have a DC path to ground (or 0 net) so be careful with the placement of capacitors.

Another common difference between simulators and real circuits appears when working with open switches. In SPICE, switches have a finite OFF resistance, while voltage probes present an infinite load. As a result, a node connected to a voltage source through an open switch can still appear at the source voltage in simulation. In real hardware, measurement instruments always provide a finite load, so the voltage would collapse. Adding even a very large load resistor in the simulation restores the expected ON/OFF behavior.

One piece of assumed knowledge stumped us. We were trying to simulate a Schmitt trigger (74HC14) and couldn’t understand why it wasn’t working as expected. The problem was the 74HC14 power connections. As shown in Figure 3, the component symbol doesn’t expose the power and GND pins.

We thought these must be set as part of the SPICE model, but if you open up Edit Symbol (Figure 4), you will see that power pin expects a net connection called VCC. We had originally been calling this power rail +5V. Note that different components use different names (e.g., VDD) and you have to use the net name specified. The 555 timer in the circuit works the same way.

LTSpice

LTspice is the SPICE simulator and schematic capture tool originally developed by Linear Technology (hence the LT) and supported by Analog Devices since they aquired them. Widely regarded as the most commonly used free SPICE simulator, you can download a copy from Analog Devices. Its spiritual successor is QSpice, developed by the original LTSpice author, but this application is currently limited to Windows.

LTSpice in EasyEDA

EasyEDA is a web-based electronic design tool that combines schematic capture, PCB layout, and circuit simulation in a single environment. It is tightly integrated with JLCPCB, allowing designs to move directly from schematic to manufacturing with minimal friction. In addition to design and layout, EasyEDA includes a built-in simulation mode for analysing circuit behavior before hardware is built (Figure 5).

In 2020, EasyEDA transitioned from using ngspice for simulation to LTSpice. For every simulation, EasyEDA converts the schematic into a text-based description of the circuit called a SPICE netlist, which is then passed to the simulator.

This SPICE netlist is not the same as the netlist used for PCB layout. A simulation netlist describes each component, how components are connected, and which models define their electrical behavior. It also includes SPICE directives that tell the simulator what analyses to run, such as transient or AC analysis, along with parameters and expressions used to define values and calculations.

We already use EasyEDA for drawing schematics and laying out PCBs, so it makes sense to use their simulation package as well. Supporting this position is the fact that the native version of LTSpice on macOS is hard work.

LTSpice on macOS

You can download a copy of the LTSpice app for macOS from the Analog Devices website. Learning LTspice on macOS is tricky because it relies on keyboard-driven interaction rather than menus. When you open the app it can be a bit daunting (Figure 6), you have a blank schematic, three tool bar icons, and no obvious way to add a component or wire. Unlike the Windows version, macOS LTspice does not expose every action through a traditional menu bar. Instead, most tasks are performed using function keys and single-key shortcuts. There is a steep learning curve, until you memorise the keys.

Table 1 summarizes the most important macOS LTspice shortcuts used during schematic entry and simulation.

By default, LTspice wires snap to horizontal and vertical directions. To draw a wire at a 45-degree angle or arbitrary direction:

1. Press F3 to start drawing a wire
2. Hold the Shift key while moving the cursor

To include external or local SPICE libraries, use the .lib directive: .lib filename. In most cases, this is sufficient. However, if LTspice fails to locate the file, explicitly referencing the current directory may be required: .lib ./filename.

All simulation commands are entered as SPICE directives:

1. Press S to open the SPICE directive dialog
2. Right-click inside the dialog window
3. Select Help me edit
4. Choose the desired analysis type:

• .TRAN — Transient analysis simulates voltages and currents as they change moment by moment. It is the most intuitive analysis and the one you usually start with
• .AC — AC analysis linearizes the circuit around its operating point and sweeps frequency. It ignores large-signal effects and time-domain behavior
• .NOISE — Noise analysis calculates the contribution of thermal and device noise to a specified output, referred back to an input source
• .DC — DC analysis sweeps a voltage source, current source, or parameter across a range and solves the steady-state operating point at each step
• .TF — Transfer function analysis computes: small-signal gain (output per unit input), input resistance, and output resistance
• .OP — Operating point analysis solves the circuit with all time-dependent sources at their DC values

This workflow avoids memorizing syntax and is especially helpful when learning or switching between analysis types.

Conclusion

If you want to use LTspice on macOS, we recommend the EasyEDA option, largely because it offers a more approachable user interface. Graphical user interfaces are hardly a novelty, and in 2026 it is reasonable to expect to place and connect components without fighting the tool. While it would be ideal to use a single schematic for both simulation and PCB layout, in practice these schematics often need to diverge slightly, so this limitation is less significant than it first appears.

To minimise friction, the best approach is usually to use the simulator that comes with your chosen EDA tool. If you already work in KiCad or Eagle, it makes sense to take advantage of their integrated ngspice-based simulation rather than introducing an entirely separate workflow.

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