OhmNote: Electronics Tube Amp

OhmNote is the electronics calculator that finally takes vacuum tubes seriously.

Whether you're designing a valve amplifier, winding a transformer, restoring vintage gear, or just learning Ohm's law, OhmNote puts many precise, beautifully crafted tools in your pocket - and it all works completely offline, with no ads and no account.

From a quick resistor color-code lookup to plotting a load line and winding your own output transformer, it's the rare toolkit that covers everyday electronics AND the deep tube-amp math most apps ignore.

BUILT FOR VACUUM-TUBE ENTHUSIASTS

Tube Analyzer - plot the load line, set the Q-point, and read gain, set bias, estimate distortion and more in real time Tube database - specs, operating points and applications for hundreds of tubes Tube pinouts - clear base diagrams at a glance for thousands of tubes Tube substitution - find compatible replacements and equivalents Tester settings - ready-to-use setups for popular tube testers

TRANSFORMERS & MAGNETICS

Output transformer (OPT) designer - turns ratio, primary inductance, air gap and saturation check Power transformer designer - VA, turns-per-volt, every winding and its wire gauge Gapped-core choke designer for power-supply filtering Air-core inductor (Wheeler) - turns ↔ inductance, both directions Transformer ratio & impedance, plus wire gauge (AWG ↔ SWG ↔ mm) Inductive Reactance of coil or transformer - inductance ↔ impedance ↔ frequency

EVERYDAY ELECTRONICS

Ohm's law & power - solve for any value Resistor color code (4/5/6-band + SMD) - read or generate Capacitor code decoder, LED resistor, voltage divider Series/parallel resistors, capacitors and inductors Reactance, RC/RL time constants, resonant frequency dB converter, frequency ↔ period

POWER & SIGNAL

Adjustable regulator (LM317 family) with heat & heatsink check Zener regulator designer Stepped attenuator (log volume control) designer RC/RL passive filters with drawn schematics Resistor & capacitor combination finder Connector pinouts - USB, HDMI, VGA, RS-232 and more

WHY YOU'LL LOVE IT

Solve forward OR reverse - enter what you know, get what you need Smart SI-unit input - just type 4.7k, 100n, 1M… Instant results as you type Fully offline - no internet required No account, no ads, privacy-first Gorgeous light & dark themes Available in English, Vietnamese, Spanish, French and German

OhmNote is made for guitar and hi-fi amp builders, audiophiles, ham radio operators, repair techs, students and working engineers - anyone who wants fast, trustworthy answers without the clutter.

Download OhmNote and build with confidence.

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