Transient Analysis

Transient Analysis #

Transient analysis is one of the most powerful tools in Breadpad’s oscilloscope, allowing you to visualize how voltages and currents change over time in your circuit. This is particularly useful for analyzing circuits with time-varying components like oscillators, filters, and digital logic.

What is Transient Analysis? #

Transient analysis simulates your circuit’s behavior over a specific time period, calculating voltages and currents at each time step. It’s like taking a series of snapshots of your circuit’s state, allowing you to see how it responds to changing inputs or startup conditions.

When to Use Transient Analysis #

  • Analyzing oscillator circuits to measure frequency, amplitude, and waveform shape
  • Testing filter responses to various input signals
  • Examining pulse responses in digital circuits
  • Measuring rise/fall times and propagation delays
  • Verifying circuit stability during power-up sequences

Using Transient Analysis in Breadpad #

Setting Up the Analysis #

  1. Place Probes: Add voltage probes to the tie points you want to measure
  2. Open the Oscilloscope: Tap the oscilloscope button in the toolbar
  3. Select Transient Analysis: Choose “Transient Analysis” from the oscilloscope menu

Configuring Parameters #

  • Start Time: The time at which to begin recording data (usually 0)
  • Stop Time: The time at which to end the simulation
  • Time Step: The interval between calculated points (smaller values increase accuracy but require more computation)
  • Maximum Voltage: Sets the vertical scale of the display

Running the Simulation #

  1. Click the “Run Simulation” button to start the analysis
  2. The oscilloscope will display voltage vs. time plots for each probe
  3. Use the interactive chart controls to zoom, pan, and examine specific regions of interest

Interpreting Results #

  • X-axis: Represents time, typically in seconds (s)
  • Y-axis: Represents voltage in volts (V) or current in amperes (A)
  • Each probe’s trace is displayed in a different color for easy identification
  • Hover over points to see exact values at specific times

Advanced Features #

  • CSV Export: Export simulation data for analysis in other software
  • Temperature Control: Adjust simulation temperature to see how your circuit behaves under different conditions (Premium feature)
  • Scaling Controls: Easily zoom in on areas of interest by adjusting the time and voltage scales
  • Measurement Cursors: Use cursors to measure time differences, frequencies, and voltage levels

Example: RC Circuit Transient Response #

A simple RC circuit’s charging behavior can be easily visualized using transient analysis:

  1. Build a circuit with a resistor and capacitor in series with a voltage source
  2. Place probes across the capacitor
  3. Configure the voltage source to output a step or pulse waveform
  4. Run transient analysis to observe the capacitor charging and discharging

You’ll see the familiar exponential curve with time constant τ = RC.

Tips for Effective Transient Analysis #

  • Start with a coarse time step for quick results, then refine for more accuracy
  • For circuits with widely varying time scales, use a variable time step
  • Save simulation configurations for repeated testing with different component values
  • Use multiple probes to understand signal relationships throughout the circuit
  • When troubleshooting, compare simulated results with expected theoretical behavior