QRCircuit was conceptualized as a Master's Thesis project at UCSB during 2013-2014. The app is designed for simulating undergraduate or graduate level amplifier configurations, filters, rectifiers, etc. It skips the schematic-based design approach to creating circuit netlists typically seen in desktop applications and instead uses native iOS elements to enable rapid circuit prototyping and simulation. This allows the app to function more as a "calculator" and makes good use of the limited screen size afforded to mobile devices.

So why is it called QRCircuit? While you can create a custom circuit netlist from scratch within the app, the app has also been designed from the start to provide a novel way to load netlists into it. Here on QRCircuit.com a repository of common netlists is provided for teaching purposes. Each circuit netlist has an accompanying QR code which goes along with it. Simply scan the QR code in the app and the netlist will be loaded in. You can then edit, add, or remove any of the circuit elements to your liking. If you would like to use these QR codes in a PDF, textbook, or blog post please feel free to do so. If you have ideas for new circuits for the repository, also please contact me. It is my goal to eventually host every major type of circuit taught in an undergraduate or graduate curriculum this way. Novel and clever circuits get extra points! Since I want the repository to be error free, any netlist you send me will be personally checked for errors and completeness before being hosted (I'll be fast I promise!).

The app is a constant work in progress, and I have plans to support and update it regularly. The goal is for it to eventually become the de-facto iOS circuit simulator. Creating a stable circuit simulation platform, especially on a mobile device, is challenging. Please be patient. Feedback is encouraged and greatly appreciated.

QRCircuit is designed to work with iOS 7+ on iPhone 5S, iPhone 5, iPhone 4S, iPhone 4, iPad Air, iPad (2nd, 3rd, or 4th generation), iPad Mini, and iPod Touch 5th generation. Neither an Android nor Windows Phone version is currently being developed.

• Academic Paper
• QRCircuit Repository
• Screenshots
• Tutorial Videos
• Common Pitfalls/Quirks -- I highly suggest reading this if you're a SPICE beginner...even experienced users might learn a thing or two! Short and sweet.
• ngspice Documentation -- The starting place to go if you can't figure out how something in SPICE functions. Help is built into the app in various places, however.
• Official Berkeley SPICE Homepage

Supported Circuit Elements:

• Resistor
• Semiconductor Resistor
• Capacitor
• Semiconductor Capacitor
• Inductor
• Inductor model
• Coupled Inductor
• Independent Source for Voltage or Current (Pulse, Sinusoidal, Exponential)
• Linear Dependent Source (VCCS, VCVS, CCCS, CCVS)
• Diode
• Diode model
• BJT (NPN, PNP)
• JFET (NJF/PJF)
• MESFET (NMF/PMF)
• MOSFET (NMOS, PMOS : Level 1, 2, and 3)

Supported Analyses:

• Small-Signal AC Analysis
• DC Transfer Function
• Operating Point Analysis
• Transient Analysis

Upcoming Features:

• Support for converting a netlist into a reasonable circuit schematic automatically for debugging purposes. Coming very soon!
• Better control over user-input to create an error-free experience
• Pole-Zero Analysis, Small-Signal Distortion Analysis, Sensitivity Analysis, Noise Analysis, Periodic Steady State Analysis
• Always working on better plotting routines ;)
• Switches / Switch model (SW/CSW)
• Better Independent Voltage / Current support: Piece-Wise Linear, Single-Frequency FM, Amplitude modulated (AM), Transient noise source, Random voltage source, External voltage or current input, Arbitrary phase Source
• Transmission line support: Lossless, Lossy, Uniform Distributed RC Lines
• True analog models: Gain, Summer, Multiplier, Divider, Limiter, Controlled Limiter, PWL Controlled Source, Analog Switch, Zener Diode, Current Limiter, Hysteresis Block, Differentiator, Integrator, Inductive Coupling, Magnetic Core, Controlled Sine Wave Oscillator, Controller Triangle Wave Oscillator, Controlled Square Wave Oscillator, Controlled One-Shot, Capacitance Meter, Inductance Meter, Memristor