Simple Signal Generator

Description SigGen is a dual-channel function generator for iPhone. It is built like a small bench instrument: log frequency, a live oscilloscope, pads, and independent outputs for channel A and B. Use it to check amplifiers, headphones, crossovers, and wiring, or to put a known pitch on a speaker. It is a test-tone source, not a synthesizer or a music app. FREQUENCY Log slider from 0.1 Hz to 20 kHz. Decade keys, user presets (100 Hz, 440 Hz, 880 Hz, 3520 Hz, 20 kHz), ±2% trim, and a keypad for an exact value. WAVEFORMS Sine, square, triangle, saw, pulse (with duty cycle), white noise, pink noise, and fade — a sine that rings down onto the x-axis. SCOPE Live preview with a 1-2-5 time/div and AUTO. The trace is the same math as the output; it does not mean the speaker is on. CHANNELS Two oscillators. Mono copies A to both ears. Stereo A/B sends A left and B right. Phase is relative between channels in stereo. SWEEP, MOD, BURST Linear or log sweep between two frequencies. AM, FM, or PM from an internal LFO. Burst gates a set number of cycles on a timer. OUTPUT Independent OUTPUT A and OUTPUT B. Two −20 dB pads per channel. Level is digital full scale (dBFS), not volts or SPL. Phone analog output is AC-coupled, so DC offset appears on the scope only. NOTES Output stops when you leave the app, unplug headphones, or another app takes audio. Tones below about 20 Hz are generated but a phone speaker or earbuds will not reproduce them usefully. Start with device volume down; a steady test tone is louder than music at the same setting.