Frequently Asked Questions #

General Questions #

What is Breadpad? #

Breadpad is a visual circuit design and SPICE simulation app for iPhone, iPad, Mac, and Apple Vision Pro. It combines the intuitive interface of a physical breadboard with the power of professional circuit simulation.

Is Breadpad free? #

Yes! Breadpad is free to download and use with generous features including all components, basic analysis types, and 2 probe points. Premium features are available via subscription.

What’s the difference between free and premium? #

Free includes: All components, DC/Transient/Operating Point analysis, 2 probes, save unlimited circuits.

Premium adds: Unlimited probes, Monte Carlo analysis, temperature sweeps, advanced sources, data export, custom IC import, and priority support.

Which devices are supported? #

Breadpad runs natively on:

iPhone (iOS 16+)
iPad (iPadOS 16+)
Mac (macOS 13+)
Apple Vision Pro (visionOS 1.0+)

One purchase/subscription covers all your devices.

Do I need internet to use Breadpad? #

No, Breadpad works completely offline. Internet is only needed for:

Initial download
iCloud sync (optional)
Purchasing subscription
Accessing online help

Circuit Design Questions #

How accurate is the simulation? #

Breadpad uses ngspice, the same professional SPICE engine used in industry. Accuracy depends on:

Component model fidelity
Numerical tolerances
Analysis settings

Results match other SPICE simulators for the same models.

Can I import LTspice/PSpice files? #

Yes! Breadpad can import standard SPICE netlists (.spice, .cir, .net). Some syntax adjustments may be needed for proprietary extensions.

What’s the maximum circuit size? #

There’s no hard limit, but performance considerations:

Free: Reasonable for educational circuits
Premium: Handles professional-complexity designs
Factors: Device speed, component count, analysis type

Can I use manufacturer SPICE models? #

Yes (Premium feature). Import .SUBCKT definitions for:

Op-amps
Voltage regulators
Special semiconductors
Any SPICE3-compatible model

Why does my circuit say “No DC path to ground”? #

Every node needs a DC path to ground reference. Solutions:

Add a high-value resistor (10MΩ) to ground
Ensure all capacitors have DC paths around them
Check for floating nodes

Simulation Questions #

What analysis types are available? #

Free:

Operating Point (DC voltages/currents)
Transient (time-domain)
DC Sweep (parameter variation)
SPICE Shell (command line)

Premium:

AC Small Signal (frequency response)
Monte Carlo (statistical)
Temperature Sweep

Why won’t my simulation converge? #

Convergence issues can be caused by:

Unrealistic component values
Missing connections
Numerical instabilities
Try adding small resistances (0.01Ω) in series with voltage sources

How do I measure current? #

Add a 0Ω resistor (or very small value like 0.001Ω) in series
Measure voltage across it
Use Ohm’s law: I = V/R
Or use SPICE shell for direct current probes

Can I simulate digital circuits? #

Yes, but Breadpad is optimized for analog. For digital:

Use voltage sources for logic levels
Add rise/fall times to prevent convergence issues
Consider simplified models
Best for mixed-signal circuits

What’s the difference between transient and AC analysis? #

Transient: Shows how circuit behaves over time (seconds, milliseconds)

Good for: Startup, pulses, oscillations

AC Analysis: Shows frequency response (Hz, kHz, MHz)

Good for: Filters, amplifiers, stability

Component Questions #

How do I model an LED? #

Use a diode with appropriate parameters:

Set forward voltage (Vf) via IS parameter
Add series resistance if needed
Typical Vf: Red=1.8V, Green=2.2V, Blue=3.3V

Can I create custom components? #

Yes, using the Chip component (Premium):

Define SPICE subcircuit
Import into Chip
Map pins
Save for reuse

How do I set component tolerances? #

Premium feature:

Edit component
Set tolerance percentage
Run Monte Carlo analysis
See statistical variations

Where do I find component datasheets? #

Tap component → Part Number field
Use Octopart integration (Premium)
Search manufacturer websites
Standard values in component descriptions

Platform-Specific Questions #

How do I sync between devices? #

Circuits sync automatically via iCloud:

Same Apple ID on all devices
iCloud Drive enabled
Breadpad folder in iCloud
Changes sync within seconds

Can I use Apple Pencil? #

Yes, on compatible iPads:

Precise component placement
Circuit annotations
Natural drawing
Pressure sensitivity

Does it work with external keyboards? #

Yes! Full keyboard support on iPad and Mac:

Shortcuts for common actions
Tab navigation
Arrow key movement
No mouse/touch required

Can I use a game controller? #

Yes! Xbox, PlayStation, and MFi controllers supported:

Navigate with D-pad
Place with buttons
Zoom with triggers
Great for accessibility

Technical Questions #

What SPICE version does Breadpad use? #

Breadpad uses ngspice, which is SPICE3-compatible with extensions:

Berkeley SPICE3 syntax
XSPICE extensions
Modern semiconductor models
Compatible with most SPICE netlists

Can I export Gerber files? #

Not currently. Breadpad focuses on circuit design and simulation, not PCB layout. Export netlist and use PCB software for layout.

Is there an API or automation? #

Not yet, but planned features include:

Siri Shortcuts
URL schemes
Scriptable actions
CI/CD integration

Can I run parametric sweeps? #

Yes, using DC Sweep for single parameters. For multiple parameters:

Use SPICE shell .STEP command
Export data for external processing
Monte Carlo for statistical variation

Troubleshooting #

The app crashes when opening #

Try these steps:

Update to latest version
Restart device
Check storage space
Reinstall if needed
Contact support with crash details

My circuits won’t sync #

Check:

Same Apple ID on all devices
iCloud Drive enabled
Good internet connection
Storage quota not exceeded
Sign out/in to iCloud

Components won’t place #

Ensure:

Aligned with tie points
Not overlapping others
Valid location for component type
Breadboard not full

Simulation is very slow #

Try:

Simpler analysis first
Reduce simulation time
Fewer probe points
Check for numerical issues
Upgrade device/subscription

Subscription & Purchase #

How do I cancel subscription? #

iOS/iPad/Mac:

Settings → [Your Name] → Subscriptions
Select Breadpad
Cancel Subscription

Continues until end of billing period.

Can I switch subscription types? #

Yes, in App Store subscriptions:

Upgrade immediately takes effect
Downgrade takes effect at renewal
No loss of data

Is there an educational discount? #

Individual education pricing: Use standard subscriptions
Institutions: Volume Purchase Program
Contact for bulk licenses

What happens to my circuits if I cancel? #

Nothing! You keep:

All saved circuits
Ability to open/view
Basic editing features
Just lose premium features

Getting Help #

How do I report a bug? #

In app: Settings → Send Feedback Include:

What you expected
What happened
Steps to reproduce
Device and OS version

Is there a user manual? #

This website is the manual! See:

Can I request features? #

Yes! We love feedback:

In-app feedback form
Email support
Community forums
Most requested features get priority

Is there a community? #

Growing community:

Reddit: r/breadpad
Discord: discord.gg/breadpad
Twitter: @breadpadapp
YouTube tutorials coming

Privacy & Security #

What data do you collect? #

Minimal, anonymized analytics:

Crash reports (optional)
Feature usage (anonymous)
No personal data
No circuit contents
See Privacy Policy

Where are my circuits stored? #

Locally on device
iCloud Drive (if enabled)
Never on our servers
You control your data

Is my data encrypted? #

iCloud: Apple’s encryption
Local: Device encryption
Export: Unencrypted files
Your responsibility for exports

Can others see my circuits? #

No, unless you:

Explicitly share files
Use shared iCloud folders
Export and send
Post screenshots

Didn’t find your answer? Contact support through the app: Settings → Send Feedback