# Transistors Handbook vs 555 Timer & Oscillators Pro

The clearest difference is update cadence: Transistors Handbook at fortnightly against 555 Timer & Oscillators Pro's every 2 months. Transistors Handbook also leads on price ($3.99 vs $4.99) and iOS requirement (11.4 vs 17.0). On ads, in-app purchases and device support there is nothing between them.

Transistors Handbook costs $3.99 and 555 Timer & Oscillators Pro $4.99 up front. Neither carries in-app purchases, so what you see is what you pay.

Transistors Handbook ships an update fortnightly, 555 Timer & Oscillators Pro every 2 months. The most recent releases landed on October 23, 2026 and October 25, 2026 respectively.

## The numbers

| Metric | Transistors Handbook | 555 Timer & Oscillators Pro |
| --- | --- | --- |
| Price | **$3.99** | $4.99 |
| Rating | **[3.9 (24 ratings)](https://appshunter.io/ios/app/transistors-handbook/id474379633/reviews)** | — |
| Number of ratings | **24** | — |
| Positive reviews | 27.3% of reviews | — |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | **Fortnightly** | Every 2 months |
| Monetization | Paid | — |
| Size | 22 MB | 22 MB |
| Requires iOS | **11.4** | 17.0 |
| Devices | iPhone, iPad, iPod | iPhone, iPad, Mac |
| Age rating | 4+ | 4+ |
| Developer | [Centro Studi Informatica di Danilo Priore](https://appshunter.io/developer/409935887) | [ALG Software Lab](https://appshunter.io/developer/1650561236) |

## What reviewers say

### Transistors Handbook

[App page](https://appshunter.io/ios/app/transistors-handbook/id474379633)

This app serves as a comprehensive guide to transistors, offering detailed information on over 51,000 types. Users can search for transistors by name or power, view graphical schemas, and access datasheets. It's designed to assist in selecting and designing electronic circuits.

**Highlights:** Database of over 51,000 transistors, Detailed transistor specifications, Graphical schema and code information, Search by name or power, Online datasheet access, Information on Silicon and Germanium transistors

**Features:** macOS Compatibility

**In-app purchases:** none


### 555 Timer & Oscillators Pro

[App page](https://appshunter.io/ios/app/555-timer-and-oscillators-pro/id6504415162)

**Features:** Vision Pro support

**In-app purchases:** none


## Frequently asked questions

### Is Transistors Handbook free?

Transistors Handbook costs $3.99, with no in-app purchases.

### Is 555 Timer & Oscillators Pro free?

555 Timer & Oscillators Pro costs $4.99, with no in-app purchases.

### Do Transistors Handbook or 555 Timer & Oscillators Pro have ads?

Neither Transistors Handbook nor 555 Timer & Oscillators Pro shows ads.

### Which is updated more often, Transistors Handbook or 555 Timer & Oscillators Pro?

Transistors Handbook ships an update fortnightly, and 555 Timer & Oscillators Pro every 2 months. Most recently, Transistors Handbook was updated on October 23, 2026 and 555 Timer & Oscillators Pro on October 25, 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.*