Frequently Asked Questions #
General #
What is Breadpad? #
Breadpad is a visual circuit design and SPICE simulation app for iPhone, iPad, Mac, and Apple Vision Pro. It pairs the feel of a physical breadboard with the ngspice simulation engine.
Is Breadpad free? #
Yes — Breadpad is free to download and use, including all components, the component library, basic analysis, and up to 2 probes. Premium unlocks advanced analysis, modeling, and data export.
What’s the difference between free and Premium? #
Free: place any component, the full part library, Operating Point / Transient
/ Real-time / SPICE Shell analysis, up to 2 probes, Bill of Materials export,
snapshots, opening any .breadpad file, and importing PSPICE/LTspice netlists.
Premium: AC Small-Signal analysis; unlimited probes and plotted signals; tolerance & Monte Carlo; temperature sensitivity; all component parameters (tolerance, TC1/TC2); advanced voltage sources (PWM, exponential, piecewise, SFFM, AM, audio); custom transistor/diode models; unlimited custom chips and chip netlist editing; CSV and WAV export.
See Pricing for the full table.
Which devices are supported? #
- iPhone — iOS 18+
- iPad — iPadOS 18+
- Mac — macOS 15+
- Apple Vision Pro — visionOS 2.0+
One purchase or subscription covers every device signed into the same Apple ID.
Do I need an internet connection? #
No. Breadpad works fully offline. Internet is only needed for the initial download, optional iCloud sync, and managing your subscription.
Circuit design #
How accurate is the simulation? #
Breadpad uses ngspice, the same engine family used across the industry. Results match other SPICE simulators for equivalent models and settings.
Can I import LTspice / PSpice files? #
Yes. Breadpad opens standard SPICE netlists (.spice, .cir) and runs them.
Some proprietary extensions may need small adjustments.
Why does my circuit say “No DC path to ground”? #
Every node needs a DC path to the ground reference. Add a high-value resistor (e.g. 1 GΩ) to a floating node, and make sure nothing is left unconnected.
Why won’t my simulation converge? #
Common causes: unrealistic component values, missing connections, or numerical edge cases. Try a simpler analysis first and add small series resistances around ideal sources.
How do I measure current? #
Place a small series resistor (e.g. 0.001 Ω), probe the voltage across it, and use I = V/R — or inspect branch currents with Operating Point analysis.
Components #
How do I model an LED? #
Use a diode. Pick a model with a suitable forward voltage (red ≈ 1.8 V, green ≈ 2.2 V, blue ≈ 3.3 V) and add a series resistor to limit current.
Can I create custom components? #
Yes, with the Chip tool: place a chip and customize its pinout and netlist. The free version allows a limited number of custom chips; Premium removes the limit and unlocks direct netlist editing.
How do I set component tolerances? #
Tolerance (and TC1/TC2) are Premium parameters. Edit a component, set its tolerance, and run a transient simulation — see Tolerance & Monte Carlo.
Platforms #
How do I sync between devices? #
Circuits sync through iCloud Drive automatically when you’re signed into the same Apple ID with iCloud Drive enabled.
Can I use Apple Pencil? #
Yes — on iPad, Apple Pencil is used to annotate circuit snapshots (markup on the captured image). Circuit building itself is done by tapping the breadboard.
Can I use a game controller? #
Yes. See Gamepad Support.
Can I export Gerber files? #
No. Breadpad focuses on circuit design and simulation, not PCB layout. Export the netlist and use dedicated PCB software for layout.
Subscription #
How do I cancel? #
Manage it in the App Store: Settings → [your name] → Subscriptions → Breadpad. Access continues until the end of the billing period.
What happens to my circuits if I cancel? #
Nothing — you keep all saved circuits and can still open and edit them. You simply lose the Premium features.
Getting help #
Is there a user manual? #
This documentation is the manual. Start with Getting Started, then browse Components and Oscilloscope & Analysis.
How do I report a bug or request a feature? #
In the app: Settings → Send Feedback. Include what you expected, what happened, and your device and OS version.
Privacy #
What data do you collect? #
Minimal, anonymized analytics and optional crash reports — no personal data and no circuit contents. See the Privacy Policy.
Where are my circuits stored? #
On your device, and in your iCloud Drive if enabled. They are never stored on our servers.