# Timer 555 Calculator Pro > Electronics circuit calculator for monostable and astable configurations. (iPhone/iPad app by Siu Yuen Ho.) - Source: https://appshunter.io/ios/app/timer-555-calculator-pro/id833443125 (this page in markdown: same URL + `.md`) - Developer: [Siu Yuen Ho](https://appshunter.io/developer/814088527) - Category: Utilities - Price: $0.99 - Rating: 4.70/5 from 3 App Store ratings · 3 written reviews indexed - Age rating: 4+ - Requires: iOS 13.2 · 3 MB - Languages: American English, French (France), German (Germany), Hindi, Italian, Japanese, Korean, European Portuguese, Russian, Chinese (Simplified, China) and 2 more - Released: 2014-03-06 - Data updated: 2026-06-04 - Monetization: paid - User reviews in markdown: https://appshunter.io/ios/app/timer-555-calculator-pro/id833443125/reviews.md ## What is Timer 555 Calculator Pro? This app is used to calculate monostable and astable circuit. Features * Calculate pulse width of monostable circuit * Calculate frequency of astable circuit * Find out combination of components making a desire pulse width in monostable circuit * Find out combination of components making a desire frequency in astable circuit * Share file to iCloud Drive (For iOS8 or later) * Share file via AirDrop Additional Features in the Professional Edition * Unlimited number of combinations * Allow to change tolerance * No ads ## Key features - Calculate monostable pulse width - Calculate astable frequency - Find component combinations - Adjust component tolerance - Unlimited combinations (Pro) - Share circuit files ## Recent user reviews (3 of 3) All indexed reviews: https://appshunter.io/ios/app/timer-555-calculator-pro/id833443125/reviews.md ### 5/5 — Nice App *2016-06-05* Overall a nice app to have. ### 5/5 — Excellent Tool *2015-09-26* This is an excellent tool for calculating the best values for a 555 circuit. ### 5/5 — Great app!! *2014-04-02* I made an astable NE555 timer/square wave generator according to app instructions (using 2% components). The result was spot on. Nice. ## Frequently asked questions about Timer 555 Calculator Pro ### What is Timer 555 Calculator Pro used for? Timer 555 Calculator Pro is used to calculate parameters for both monostable and astable 555 timer circuits. It helps you determine component values for desired pulse widths or frequencies. ### Does Timer 555 Calculator Pro have ads? No, Timer 555 Calculator Pro is ad-free. The Pro edition specifically mentions 'No ads' as a feature. ### How much does Timer 555 Calculator Pro cost? Timer 555 Calculator Pro is a paid app, priced at $0.99. This price grants you access to its full functionality. ### What devices does Timer 555 Calculator Pro support? Timer 555 Calculator Pro is available for iPhone, iPad, and iPod. It is designed to run on Apple's mobile operating systems. ### How often is Timer 555 Calculator Pro updated? The app was last updated on March 25, 2024, indicating active development. The latest version is 3.0.15. ### What is the age rating for Timer 555 Calculator Pro? Timer 555 Calculator Pro has an age rating of 4+. This suggests it is suitable for a wide range of users, including younger individuals interested in electronics. ### Can I share my circuit calculations with others using Timer 555 Calculator Pro? Yes, you can share your circuit files via iCloud Drive (for iOS 8 and later) and AirDrop. This allows for easy collaboration and backup of your designs. ### What are the benefits of the Professional Edition of Timer 555 Calculator Pro? The Professional Edition offers unlimited component combinations and the ability to change component tolerance, providing greater flexibility for complex circuit designs. It also guarantees no ads. ## Version history (last 5 releases) ### 3.0.15 — 2024-03-25 Fix minor bugs ### 3.0.10 — 2021-06-15 * Add Hindi * Fix minor bugs ### 3.0.0 — 2021-05-16 Fix minor bugs ### 2.9.5 — 2021-04-29 Fix minor bugs ### 2.9.2 — 2020-02-17 - Support German, Japanese, Chinese ## Apps similar to Timer 555 Calculator Pro | App | Rating | Price | Category | | --- | --- | --- | --- | | [武威慧停车](https://appshunter.io/ios/app/id1448009640) | — | Free | Utilities | | [GHIA KIDS](https://appshunter.io/ios/app/ghia-kids/id1434789680) | — | Free | Utilities | | [HeatNext](https://appshunter.io/ios/app/heatnext/id1440372440) | — | Free | Utilities | | [Potdeco](https://appshunter.io/ios/app/potdeco/id1438455380) | — | Free | Utilities | | [Quality Welding Time Tracker](https://appshunter.io/ios/app/quality-welding-time-tracker/id1433956880) | 1.0 (1) | Free | Utilities | | [盟帝亞電梯](https://appshunter.io/ios/app/id1435025340) | — | Free | Utilities | ## More apps by Siu Yuen Ho - [Easy Ohm's Law](https://appshunter.io/ios/app/easy-ohms-law/id814088524) - [RC Circuit Pro](https://appshunter.io/ios/app/rc-circuit-pro/id824145786) - [RC Circuit](https://appshunter.io/ios/app/rc-circuit/id824460716) - [Resistor Tools Pro](https://appshunter.io/ios/app/resistor-tools-pro/id825620924) - [Resistor Tools](https://appshunter.io/ios/app/resistor-tools/id826045228) All apps by Siu Yuen Ho: https://appshunter.io/developer/814088527 ## Related topics [timer 555 calculator pro](https://appshunter.io/ios/topics/timer-555-calculator-pro) · [timer 555 calculator](https://appshunter.io/ios/topics/timer-555-calculator) --- *Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-06-04.*