Getting Started

Getting Started with Breadpad #

This guide walks you through building your first circuit and running a simulation. You’ll have an LED circuit working in a few minutes.

The interface #

  • Toolbox — pick a tool: the Oscilloscope (probes), Wire, or a component (Resistor, Capacitor, Inductor, Diode, Transistor, Chip, Voltage Source, Transmission Line).
  • Breadboard — a grid of tie points with power rails and a center divider, just like a physical breadboard. Components placed at connected tie points are wired together automatically.
  • Oscilloscope — open it from the toolbar to choose an analysis mode and run the simulation.

Getting around: tap a tie point to move the cursor; pinch to zoom (25%–250%) or use the on-screen zoom buttons; drag with two fingers to pan. Tap a placed component to select and edit it; long-press (or right-click) for a context menu.

Your first circuit: LED with resistor #

1. New document #

Create a new circuit. You’ll see an empty breadboard.

2. Add a voltage source #

Select Voltage Source from the toolbox and tap the breadboard to place it. Tap it to edit, set it to 5 V DC.

3. Add a resistor #

Select Resistor, place it, then tap it and set 220 Ω. This limits the current through the LED.

4. Add a diode (as the LED) #

Select Diode and place it. Mind its direction — the arrow points to the cathode.

5. Wire it up #

Select Wire and tap two tie points to connect them. Connect the source’s positive terminal → resistor → diode anode, and the diode cathode → source negative.

6. Add probes #

Select the Oscilloscope tool and tap tie points to drop measurement probes — one at the resistor/diode junction and one at the diode cathode. The free version plots up to two probes.

7. Run it #

Open the oscilloscope, choose Operating Point, and tap Run Simulation.

What to expect: about 2 V across the LED (typical forward voltage), about 3 V across the resistor, and roughly 13.6 mA through the loop ((5 V − 2 V) / 220 Ω).

Editing component values #

Tap a component to open its editor. Values accept SI prefixes (10k, 100n, 2.2M) and you can set the number of significant figures to record the precision you intend. Every numeric field has a built-in engineering calculator for exact arithmetic.

Tolerances and temperature coefficients (TC1/TC2) are Premium parameters.

Analysis modes #

  • Operating Point — DC voltages and currents (free).
  • Transient — voltage vs. time (free).
  • Real-time — a continuously updating live view (free).
  • SPICE Shell — view and run the raw netlist (free).
  • AC Small-Signal — frequency response (Premium).

See Oscilloscope for details.

Next circuits to try #

Breadpad ships with example circuits — open them from the document browser to learn by exploring. Good ones to start with: Voltage Divider, Capacitors / RC Circuits, 555 Timer, and LM358 Operational Amplifier.

Troubleshooting #

  • “No DC path to ground” — every node needs a DC path to ground. Add a large resistor (e.g. 1 GΩ) to a floating node if needed.
  • Convergence failed — check for unrealistic values and missing connections; try a simpler analysis first.
  • Component won’t place — it must align to tie points and can’t overlap existing chips, voltage sources, or transmission lines.

More help: Troubleshooting · FAQ · in the app, Settings → Send Feedback.

Platform notes #

  • iPhone / iPad — touch-first; pinch to zoom, two-finger pan. iPad supports external keyboards and game controllers; Apple Pencil can annotate snapshots.
  • Mac — standard document shortcuts (⌘N, ⌘S, ⌘Z), right-click context menus, multiple windows.
  • Vision Pro — view your breadboard as a 3D volume.

See Keyboard Shortcuts and Platform Support.

Where to next #