uSimmics (formerly QucsStudio) is a free circuit simulator supporting both analog and digital circuit simulation. This article provides a detailed walkthrough of building a basic resistor circuit and running a DC analysis using uSimmics.
DC analysis is the starting point of circuit simulation. By identifying the voltage and current at each node, you can quickly validate the correctness of your design.
What You Will Learn
- How to create a resistor circuit in uSimmics (formerly QucsStudio)
- How to run a DC analysis (DC Bias calculation)
- How to read node voltages and branch currents from simulation results
- Fundamental operations: placing components, wiring, and editing properties
- Common pitfalls for beginners and how to resolve them
What Is DC Analysis?
DC analysis (direct current analysis) is a simulation that calculates the voltage and current at every node in a circuit when a DC voltage or current source is applied. In uSimmics (formerly QucsStudio), this is performed with a single click using the Calculate DC Bias function — no additional simulation component is required.
Step-by-Step Procedure
1. Selecting and Placing Components
Begin by placing the following components on the schematic.
| Component | Location (Menu) |
|---|---|
| Resistor | Lumped Components → Resistor |
| DC Voltage Source | Sources → dc Voltage Source |
| Current Probe | Devices → Current Probe |
Placement procedure:
- Select the desired component from the component panel and move the cursor over the schematic area.
- Right-click to rotate the component to the desired orientation.
- Left-click to place it at the current position.
2. Building the Circuit
After placing all components, connect them with wires.
- Add a ground symbol (GND) and connect it to the appropriate node.
- Use wires to connect the components together.
- If a wire bends in an unintended direction, right-click to toggle the bending direction.
3. Editing Component Properties
Set the values for each component.
- Double-click a component to open its property dialog.
- Example values used in this tutorial:
- R1 = 100 Ω
- R2 = 300 Ω
- Voltage source = 1 V
Values can also be edited directly on the schematic, but using the dialog is more reliable.
4. Running the DC Analysis
Once the schematic is complete, run the DC Bias simulation.
- Click the “Calculate DC Bias” button in the upper-right area of the screen.
- The calculation runs automatically, and the results are displayed directly on the schematic.
Note: DC analysis requires no additional simulation component to be added to the schematic — it executes with a single click. This distinguishes it from Transient and AC analyses.
5. Reviewing the Simulation Results
When the DC Bias analysis completes, node voltages are displayed directly on the schematic.
- Voltages: Automatically shown at each node (wire junction)
- Currents: Displayed at any Current Probe placed in the circuit
Example results (R1 = 100 Ω, R2 = 300 Ω, supply = 1 V):
| Node | Voltage |
|---|---|
| Voltage source (+ terminal) | 1.00 V |
| R1–R2 junction | 0.75 V |
| GND | 0 V |
Summary
In uSimmics (formerly QucsStudio), DC analysis is as straightforward as building the schematic and clicking “Calculate DC Bias.” The node voltages and branch currents are displayed instantly — no complex configuration required. Start with a simple resistor circuit to get familiar with the workflow, then gradually apply the same approach to more complex designs.
Related Articles
- Overview and Getting Started with uSimmics (formerly QucsStudio)
- uSimmics (formerly QucsStudio) Circuit Editor Basic Operations Guide [2026]
- Introduction to Digital Simulation in uSimmics (formerly QucsStudio) [2026]
- Circuit Optimization Guide in uSimmics (formerly QucsStudio) [2026]
- Creating and Using Subcircuits in uSimmics (formerly QucsStudio) [2026]
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