Electrical Circuit Examples

Create professional IEEE-standard electrical schematics with SPICE netlist export.

RC Lowpass Filter

A classic RC filter circuit with SPICE simulation.

DSL Code

electrical "RC Lowpass Filter" {
  net IN, OUT, GND

  # Input voltage source: 1V sine wave at 1kHz
  part V1 type:V source:"SIN(0 1 1k)" pins:(IN,GND)

  # Filter components
  part R1 type:R value:"10k" pins:(IN,OUT)
  part C1 type:C value:"1n" pins:(OUT,GND)

  # Transient analysis: 0 to 5ms
  analysis tran "0 5m"
}

Generated SVG

Exported SPICE Netlist

* RC Lowpass Filter
* Generated by Runiq

V1 IN GND SIN(0 1 1k)
R1 IN OUT 10k
C1 OUT GND 1n

.tran 0 5m
.end

Circuit Analysis

Cutoff Frequency: $f_c = \frac{1}{2\pi RC} = \frac{1}{2\pi \times 10k\Omega \times 1nF} \approx 15.9 \text{ kHz}$

Transfer Function: $H(s) = \frac{1}{1 + sRC}$

Use Cases:

• Anti-aliasing filters
• Noise reduction
• Signal smoothing

Voltage Divider

Simple resistor divider for voltage scaling.

DSL Code

electrical "Voltage Divider" {
  net VIN, VOUT, GND

  # Input: 12V DC
  part VIN type:V source:"DC 12" pins:(VIN,GND)

  # Divider resistors
  part R1 type:R value:"10k" pins:(VIN,VOUT)
  part R2 type:R value:"10k" pins:(VOUT,GND)

  # DC operating point analysis
  analysis op
}

Generated SVG

Circuit Calculation

For equal resistors: $$V_{OUT} = V_{IN} \times \frac{R_2}{R_1 + R_2} = 12V \times \frac{10k}{10k + 10k} = 6V$$

General formula: $$V_{OUT} = V_{IN} \times \frac{R_2}{R_1 + R_2}$$

Op-Amp Non-Inverting Amplifier

Operational amplifier in non-inverting configuration.

DSL Code

electrical "Non-Inverting Amplifier" {
  net IN, OUT, GND, VCC, VEE

  # Power supplies
  part VCC type:V source:"DC 15" pins:(VCC,GND)
  part VEE type:V source:"DC -15" pins:(GND,VEE)

  # Input signal: 100mV AC at 1kHz
  part VIN type:V source:"AC 0.1 1k" pins:(IN,GND)

  # Op-amp (741 or similar)
  part U1 type:OPAMP model:"LM741" pins:(IN,OUT,VCC,VEE,GND)

  # Feedback network
  part R1 type:R value:"1k" pins:(OUT,GND)
  part R2 type:R value:"10k" pins:(OUT,IN)

  # AC analysis: 10Hz to 100kHz
  analysis ac "dec 10 10 100k"
}

Generated SVG

Gain Calculation

Voltage Gain: $A_v = 1 + \frac{R_2}{R_1} = 1 + \frac{10k}{1k} = 11$ (20.8 dB)

Input Impedance: Very high (ideally infinite)

Output Impedance: Very low (ideally zero)

Supported Components

Runiq supports standard SPICE component types:

Component	Type	Syntax Example
Resistor	R	part R1 type:R value:"10k" pins:(A,B)
Capacitor	C	part C1 type:C value:"1u" pins:(A,B)
Inductor	L	part L1 type:L value:"10m" pins:(A,B)
Voltage Source	V	part V1 type:V source:"DC 5" pins:(A,B)
Current Source	I	part I1 type:I source:"DC 1m" pins:(A,B)
Diode	D	part D1 type:D model:"1N4148" pins:(A,K)
BJT Transistor	Q	part Q1 type:Q model:"2N2222" pins:(C,B,E)
MOSFET	M	part M1 type:M model:"2N7000" pins:(D,G,S)
Op-Amp	OPAMP	part U1 type:OPAMP model:"LM741" pins:(IN+,IN-,OUT,VCC,VEE)

Voltage Sources

DC Source

part VCC type:V source:"DC 5" pins:(VCC,GND)

AC Source

part VIN type:V source:"AC 1 1k" pins:(IN,GND)
# AC amplitude 1V, frequency 1kHz

Sine Wave

part VSIN type:V source:"SIN(0 1 1k)" pins:(IN,GND)
# Offset 0V, amplitude 1V, frequency 1kHz

Pulse

part VPULSE type:V source:"PULSE(0 5 0 1n 1n 500n 1u)" pins:(IN,GND)
# Low, High, Delay, Rise, Fall, Width, Period

SPICE Analysis Types

DC Operating Point

analysis op

Calculates DC voltages and currents at all nodes.

Transient Analysis

analysis tran "0 10m"
# Start time, Stop time

Time-domain simulation.

AC Analysis

analysis ac "dec 10 10 100k"
# Sweep type, points/decade, start freq, stop freq

Frequency response (Bode plots).

DC Sweep

analysis dc "VIN 0 10 0.1"
# Source name, start, stop, step

Sweep voltage/current and plot response.

Value Suffixes

Standard SPICE suffixes for component values:

Suffix	Multiplier	Example	Value
f	$10^{-15}$	1f	1 femto
p	$10^{-12}$	10p	10 pico
n	$10^{-9}$	1n	1 nano
u	$10^{-6}$	10u	10 micro
m	$10^{-3}$	1m	1 milli
k	$10^{3}$	10k	10 kilo
Meg	$10^{6}$	1Meg	1 mega
G	$10^{9}$	1G	1 giga

Complete Examples

LED Circuit with Current Limiting

electrical "LED Circuit" {
  net VCC, LED_ANODE, GND

  # 5V power supply
  part V1 type:V source:"DC 5" pins:(VCC,GND)

  # Current limiting resistor: (5V - 2V) / 20mA = 150Ω
  part R1 type:R value:"150" pins:(VCC,LED_ANODE)

  # Red LED (forward voltage ~2V)
  part LED1 type:D model:"LED_RED" pins:(LED_ANODE,GND)

  analysis dc "V1 0 10 0.1"
}

Generated SVG

RLC Resonant Circuit

electrical "RLC Resonant Circuit" {
  net IN, OUT, GND

  # AC voltage source: 1V at variable frequency
  part V1 type:V source:"AC 1" pins:(IN,GND)

  # Series RLC components
  part R1 type:R value:"10" pins:(IN,OUT)
  part L1 type:L value:"10m" pins:(OUT,GND)
  part C1 type:C value:"1u" pins:(OUT,GND)

  # AC analysis: 100Hz to 10kHz
  analysis ac "dec 50 100 10k"
}

Generated SVG

Resonant Frequency

$$f_0 = \frac{1}{2\pi\sqrt{LC}} = \frac{1}{2\pi\sqrt{10mH \times 1\mu F}} \approx 1.59 \text{ kHz}$$

Use Cases:

• Bandpass filters
• Oscillator circuits
• RF tuning circuits
• Quality factor (Q) measurement

Full Bridge Rectifier

electrical "Bridge Rectifier" {
  net AC_IN, DC_PLUS, DC_MINUS, GND

  # AC input: 120V RMS at 60Hz
  part VAC type:V source:"SIN(0 170 60)" pins:(AC_IN,GND)

  # Bridge diodes
  part D1 type:D model:"1N4007" pins:(AC_IN,DC_PLUS)
  part D2 type:D model:"1N4007" pins:(GND,AC_IN)
  part D3 type:D model:"1N4007" pins:(GND,DC_PLUS)
  part D4 type:D model:"1N4007" pins:(DC_MINUS,GND)

  # Filter capacitor
  part C1 type:C value:"1000u" pins:(DC_PLUS,DC_MINUS)

  # Load resistor
  part RL type:R value:"100" pins:(DC_PLUS,DC_MINUS)

  analysis tran "0 100m"
}

Best Practices

Component Naming

• Use descriptive IDs: R_PULLUP, C_FILTER, LED_STATUS
• Follow SPICE conventions: R1, R2, C1, C2, etc.
• Group related components: R_FB1, R_FB2 (feedback network)

Net Naming

• Always define GND as reference
• Use meaningful names: VCC, VIN, VOUT, DATA, CLK
• Group signals: BUS_D0, BUS_D1, etc.

Simulation Settings

• Start with DC operating point (op) to verify bias
• Use transient (tran) for time-domain behavior
• Use AC analysis for frequency response
• Choose appropriate time scales and frequencies

Export to SPICE

Generate SPICE netlists for simulation in:

• LTspice (free, Windows/Mac/Linux)
• Ngspice (open source)
• PSPICE (commercial)
• Xyce (high-performance, parallel)

# Generate SPICE netlist
runiq rc-filter.runiq --export spice -o rc-filter.cir

# Simulate with ngspice
ngspice rc-filter.cir

Next Steps

• Digital Circuits → - Logic gates and HDL export
• Block Diagrams → - Control systems
• Reference → - All electrical symbols

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Download Examples

All example .runiq files are available in the GitHub repository.

git clone https://github.com/jgreywolf/runiq.git
cd runiq/examples/electrical