# RC Circuit vs HSA

The clearest difference is in-app purchases: HSA at none against RC Circuit's 1. HSA also leads on update cadence (every 2 months vs every 6 months) and iOS requirement (8.0 vs 12.0). On price, ads and device support there is nothing between them.

Both are free to download. RC Circuit sells 1 one-off in-app purchase. HSA asks for nothing beyond the download.

RC Circuit ships an update every 6 months, HSA every 2 months. The most recent releases landed on October 5, 2026 and October 7, 2026 respectively.

## The numbers

| Metric | RC Circuit | HSA |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[4.8 (5 ratings)](https://appshunter.io/ios/app/rc-circuit/id824460716/reviews)** | — |
| Number of ratings | **5** | — |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Update frequency | Every 6 months | **Every 2 months** |
| Monetization | Free | — |
| Size | 16 MB | 10 MB |
| Requires iOS | 12.0 | **8.0** |
| Devices | **iPhone, iPad, iPod** | iPhone, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Siu Yuen Ho](https://appshunter.io/developer/814088527) | [杏生 卢](https://appshunter.io/developer/1094592555) |

## What reviewers say

### RC Circuit

[App page](https://appshunter.io/ios/app/rc-circuit/id824460716)

Calculate RC charging and filter circuits, including time constants and cutoff frequencies. Find component values from these parameters or get voltage at specific times. Save and share data easily.

**Highlights:** Calculate time constant, Find component values, Get voltage at time t, Calculate cutoff frequency, Save data to CSV, Upload CSV via AirDrop/iCloud Drive, Multi-language support

**Features:** Vision Pro support

**In-app purchases (1)**

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


### HSA

[App page](https://appshunter.io/ios/app/hsa-dsppro/id1323479757)

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is RC Circuit free?

RC Circuit is free to download, with in-app purchases available.

### Is HSA free?

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

### Do RC Circuit or HSA have ads?

Neither RC Circuit nor HSA shows ads.

### Which is updated more often, RC Circuit or HSA?

RC Circuit ships an update every 6 months, and HSA every 2 months. Most recently, RC Circuit was updated on October 5, 2026 and HSA on October 7, 2026.

---

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