# Timer 555 Calculator vs LED System

The clearest difference is in-app purchases: LED System at none against Timer 555 Calculator's 1. LED System also leads on update cadence (weekly vs every 3 months). Timer 555 Calculator's advantage is iOS requirement (13.2 vs 15). On price, ads and device support there is nothing between them.

Both are free to download. Timer 555 Calculator sells 1 one-off in-app purchase. LED System asks for nothing beyond the download.

Timer 555 Calculator ships an update every 3 months, LED System weekly. The most recent releases landed on September 24, 2026 and September 15, 2026 respectively.

## The numbers

| Metric | Timer 555 Calculator | LED System |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[3.9 (8 ratings)](https://appshunter.io/ios/app/timer-555-calculator/id834044557/reviews)** | — |
| Number of ratings | **8** | — |
| Positive reviews | 100.0% of reviews | — |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Update frequency | Every 3 months | **Weekly** |
| Monetization | Free with in-app purchases | — |
| Size | 3 MB | 64 MB |
| Requires iOS | **13.2** | 15 |
| Devices | **iPhone, iPad, iPod** | iPhone, iPod |
| Age rating | 4+ | 17+ |
| Developer | [Siu Yuen Ho](https://appshunter.io/developer/814088527) | [深圳市流明电子有限公司](https://appshunter.io/developer/1031986405) |

## What reviewers say

### Timer 555 Calculator

[App page](https://appshunter.io/ios/app/timer-555-calculator/id834044557)

Calculate monostable and astable circuits for electronics projects. Determine pulse width and frequency, find component combinations, and save/upload data. Supports multiple languages.

**Highlights:** Monostable circuit pulse width calculation, Astable circuit frequency calculation, Component combination finder, Save component values to CSV, Upload CSV via AirDrop/iCloud Drive, Multi-language support

**Features:** Vision Pro support

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Unlock Pro feature | $0.99 | one-time |


### LED System

[App page](https://appshunter.io/ios/app/led-system/id6670427885)

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is Timer 555 Calculator free?

Timer 555 Calculator is free to download, with in-app purchases available.

### Is LED System free?

LED System is free to download, with no in-app purchases.

### Do Timer 555 Calculator or LED System have ads?

Neither Timer 555 Calculator nor LED System shows ads.

### Which is updated more often, Timer 555 Calculator or LED System?

Timer 555 Calculator ships an update every 3 months, and LED System weekly. Most recently, Timer 555 Calculator was updated on September 24, 2026 and LED System on September 15, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*