Frequency Generator from WWII

Frequency Generator 1940 turns your iPhone into a signal generator styled after the field test equipment radio operators and engineers relied on in the 1940s — an amber dial glow, mechanical-style toggle switches, a hand-turned knob, and a nameplate riveted straight onto the back panel, serial number and all. Underneath the vintage face is a modern, precise tool. Dial in any frequency from 20 Hz to 20 kHz on a logarithmic knob built for fine control, or jump straight to a musical note with the built-in note picker (C0–B7). Choose from four waveforms — sine, square, triangle, sawtooth — and sweep continuously across the full audible range with one tap. Whether you're testing speakers, checking your hearing range, tuning an instrument by ear, or just want a clean tone on demand, it gets you there with no menus to dig through and no ads to sit through — the same directness as the hardware…