OhmNote: Electronics Tube Amp
Transformers & Valve Pinouts
Free · In‑App Purchases · Designed for iPad. Not verified for macOS.
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.
Terms of Use (EULA): https://ohmnote.com/terms
Privacy Policy: https://ohmnote.com/privacy
Ratings & Reviews
• Tube analyzer now opens at each tube's datasheet operating point.
• Load impedance range now comes from the tube instead of a fixed limit.
• Fix Tube Database feature for showing pinout and tube subtitution.
• Russian designations (6Л6, 6Н3П…) now find the right tube.
• New tube: 26 (UX-226).
The developer, Sang Truong, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Collected
The developer does not collect any data from this app.
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- Sang Truong
- Size
- 30.5 MB
- Category
- Utilities
- Compatibility
Requires iOS 15.6 or later.
- iPhone
Requires iOS 15.6 or later. - iPad
Requires iPadOS 15.6 or later. - iPod touch
Requires iOS 15.6 or later. - Mac
Requires macOS 12.5 or later and a Mac with Apple M1 chip or later. - Apple Vision
Requires visionOS 1.0 or later.
- iPhone
- Languages
- English
- Age Rating
13+
- 13+
- In-App Purchases
Yes
- Gói trọn đời $39.99
- Hàng năm $14.99
- Hàng tháng $2.99
- Copyright
- © OhmNote