Electronic Tutorials

Step-by-step electronics learning guides

Getting Started Tutorials

Tutorial 1: Your First Circuit

Learn the basics by building a simple LED circuit.

What You’ll Learn

  • How to add components
  • Making connections
  • Running simulations
  • Using basic measurement tools

Step-by-Step Instructions

  1. Start with a New Circuit
    • Open CircuitJS1
    • You should see a blank canvas
  2. Add a Voltage Source
    • Right-click on empty space
    • Navigate to: Inputs and Sources > Voltage Source (DC)
    • Click to place the voltage source
    • Right-click the voltage source and select Edit
    • Set voltage to 5V
  3. Add a Resistor
    • Right-click on empty space
    • Navigate to: Passive Components > Resistor
    • Place the resistor near the voltage source
    • Edit the resistor value to 330Ω
  4. Add an LED
    • Right-click on empty space
    • Navigate to: Active Components > LED
    • Place the LED in your circuit
  5. Make Connections
    • Click on the positive terminal of the voltage source
    • Drag to one end of the resistor
    • Connect the other end of the resistor to the LED anode (positive)
    • Connect the LED cathode (negative) back to the voltage source negative terminal
  6. Run the Simulation
    • Press Space or click the play button
    • The LED should light up!

What’s Happening?

  • The resistor limits current through the LED
  • Without it, the LED would be damaged by excessive current
  • Current flows from positive to negative through the complete circuit

Tutorial 2: RC Timing Circuit

Build a circuit that demonstrates capacitor charging and discharging.

Components Needed

  • 12V DC voltage source
  • 1kΩ resistor
  • 100µF capacitor
  • Switch
  • Voltmeter or scope probe

Circuit Construction

  1. Build the Basic RC Circuit
    • Place voltage source, resistor, and capacitor in series
    • Add a switch in series to control the circuit
  2. Add Measurement
    • Right-click on the capacitor
    • Select View in Scope to monitor voltage
    • Or add a voltmeter across the capacitor
  3. Observe Charging
    • Close the switch
    • Watch the capacitor voltage rise exponentially
    • Note the time constant τ = RC = 1kΩ × 100µF = 0.1 seconds
  4. Observe Discharging
    • Add a second switch to discharge the capacitor through a resistor
    • Watch the exponential decay

Key Learning Points

  • Time Constant: τ = RC determines charging/discharging speed
  • 63% Rule: Capacitor reaches 63% of final voltage in one time constant
  • Exponential Behavior: Charging follows 1 - e^(-t/τ), discharging follows e^(-t/τ)

Tutorial 3: Op-Amp Basics

Learn operational amplifier fundamentals with a non-inverting amplifier.

Theory Review

  • Op-amps have very high gain (ideally infinite)
  • Golden Rules:
    1. No current flows into the inputs
    2. The op-amp tries to make both inputs equal

Building the Circuit

  1. Add the Op-Amp
    • Use Active Components > Op-Amp (ideal)
    • This gives us perfect characteristics for learning
  2. Create the Feedback Network
    • Connect a 10kΩ resistor from output to inverting input (-)
    • Connect a 1kΩ resistor from inverting input to ground
  3. Add Input Signal
    • Connect an AC voltage source (1V, 1kHz) to the non-inverting input (+)
  4. Power Supply
    • Connect ±15V supplies to the op-amp power pins
  5. Measure Output
    • Use scope to monitor both input and output

Expected Results

  • Gain: (R1 + R2) / R2 = (10k + 1k) / 1k = 11
  • Output: 11V peak-to-peak sine wave
  • Phase: Input and output are in phase (non-inverting)

Intermediate Tutorials

Tutorial 4: Digital Logic

Build and test basic logic gates and combinations.

Part A: Individual Gates

  1. Test AND Gate

    • Add 2-input AND gate
    • Connect logic switches to inputs
    • Connect LED to output
    • Test all four input combinations

  2. Truth Table Verification

    A | B | Output
0 | 0 |   0
0 | 1 |   0
1 | 0 |   0
1 | 1 |   1

Part B: Combinational Logic

Build a simple combinational circuit: (A AND B) OR (C AND D)

  1. Use Multiple Gates
    • 2× AND gates
    • 1× OR gate
    • 4× input switches
    • 1× output LED
  2. Test Systematically
    • Create a truth table
    • Test each combination
    • Verify expected behavior

Tutorial 5: Oscillators

Create circuits that generate their own timing signals.

Relaxation Oscillator

Using an op-amp comparator with RC timing:

  1. Basic Configuration
    • Op-amp as comparator
    • RC timing network
    • Positive feedback for hysteresis
  2. Component Values
    • Timing: R = 10kΩ, C = 1µF
    • Feedback: R1 = 10kΩ, R2 = 10kΩ
    • Frequency ≈ 1/(2.2 × RC) ≈ 45 Hz

Multivibrator Using Logic Gates

  1. Ring Oscillator
    • Chain of NOT gates (odd number)
    • RC delay networks
    • Observe frequency vs. number of stages

Advanced Tutorials

Tutorial 6: Active Filters

Design and build active filter circuits.

Low-Pass Filter

  1. Sallen-Key Topology
    • Op-amp buffer configuration
    • Two RC stages
    • Unity gain version
  2. Design Process
    • Choose cutoff frequency (fc = 1000 Hz)
    • Calculate component values
    • R = 1.6kΩ, C = 100nF
  3. Frequency Response
    • Sweep input frequency from 10 Hz to 100 kHz
    • Plot magnitude response
    • Verify -3dB point at cutoff frequency
    • Observe -40dB/decade roll-off above cutoff

High-Pass Filter

  1. Swap R and C positions from low-pass design
  2. Same cutoff frequency calculation
  3. Opposite response: passes high frequencies, rejects low

Tutorial 7: Power Supply Design

Build a complete linear power supply.

Transformer and Rectification

  1. Step-Down Transformer
    • 120V AC input
    • 24V AC output
    • Center-tapped for full-wave rectification
  2. Bridge Rectifier
    • 4× 1N4007 diodes
    • Convert AC to pulsating DC
  3. Filter Capacitor
    • Large electrolytic capacitor (1000µF)
    • Smooth the pulsating DC

Voltage Regulation

  1. Three-Terminal Regulator
    • LM7812 for +12V output
    • Input and output capacitors
    • Heat sink considerations
  2. Load Testing
    • Variable load resistor
    • Monitor regulation under different loads
    • Measure ripple and regulation

Troubleshooting Tutorials

Common Circuit Problems

Problem: Circuit Doesn’t Work

Systematic Debugging Approach:

  1. Check Power
    • Verify voltage sources are connected
    • Measure actual voltages with scope/meter
  2. Verify Connections
    • Look for broken or missing connections
    • Check for short circuits
  3. Component Values
    • Double-check all component values
    • Ensure realistic values (not too large/small)
  4. Grounding
    • Ensure proper ground connections
    • One common reference point

Problem: Oscilloscope Shows Nothing

  1. Signal Present?
    • Check if circuit is actually running
    • Verify signal source is active
  2. Scope Settings
    • Appropriate time base
    • Correct voltage scale
    • Signal within scope range
  3. Probe Connections
    • Verify probe points
    • Check for high-impedance nodes

Practice Exercises

Exercise 1: Design Challenges

  1. LED Flasher: Create a circuit that blinks an LED at 1 Hz
  2. Voltage Divider: Design a circuit that outputs exactly 3.3V from 5V
  3. Logic Function: Implement F = A’B + AB’ (XOR function) using only NAND gates

Exercise 2: Analysis Practice

Given existing circuits: 1. Calculate expected voltages and currents 2. Verify with simulation 3. Explain any discrepancies

Exercise 3: Optimization

Take a working circuit and: 1. Reduce component count 2. Improve efficiency 3. Add protection features

Next Steps

After completing these tutorials:

  1. Explore Examples: Check out the Circuit Examples
  2. Read the User Guide: Detailed reference in User Guide
  3. Contribute: Learn about Contributing to the project
  4. Build from Source: See Building Guide for development

These tutorials progress from basic concepts to advanced circuit design. Take your time with each section and experiment with variations to deepen your understanding.