Design, simulate, and learn the legendary NE555 timer chip — right on your iPhone or iPad. Whether you’re a hobbyist building your first LED blinker or an engineer prototyping a PWM driver, 555 Timer Calculator delivers instant, textbook-accurate results with a live oscilloscope waveform you can watch in real time. KEY FEATURES • Astable (Oscillator) Mode Compute frequency, period, duty cycle, Ton and Toff from R1, R2 and C. The square wave animates on a retro green-phosphor oscilloscope so you see exactly what your circuit will output. • Monostable (One-Shot) Mode Get precise pulse width T = 1.1 × R × C for time delays, switch debouncers and trigger circuits. Watch the trigger and output pulses animate side by side. • Interactive Inputs Drag the sliders or tap to type values directly. Full unit support — Ω, kΩ, MΩ and pF, nF, μF. • Live Waveform & Duty Cycle Ring Animated oscilloscope with pinch-style zoom plus a colour-coded duty cycle ring let you spot timing problems at a glance. • Ready-Made Preset Circuits Tap a preset to load proven designs: 1 Hz LED blinker, 1 kHz audio tone, 10 ms debounce pulse, 100 ms delay, 50 % square wave and 75 % PWM for motors. • Built-In 555 Reference A complete in-app guide explains how the 555 works internally, every pin (VCC, GND, TRG, OUT, RST, CTL, THR, DIS), all formulas, common uses and practical design tips for stable, accurate timing. WHO IT’S FOR Electronics students, makers building Arduino and Raspberry Pi peripherals, EE professionals prototyping clocks and PWM drivers, ham radio operators, robotics enthusiasts and anyone who has ever reached for a breadboard. WHY 555 TIMER CALCULATOR No internet required. No accounts. No subscriptions. No ads. Just a fast, precise, beautifully designed engineering tool with a dark-mode oscilloscope aesthetic. Every formula matches the standard datasheets used by Texas Instruments, NXP and ON Semiconductor. Thanks for your support and visit nitrio.com for more apps for your iOS devices.