# EL tools: Circuit Calculator — Quick calcs for circuit design

> Quick calcs for circuit design (iPhone/iPad app by KAZE Application.)

- Source: https://appshunter.io/ios/app/el-tools-circuit-calculator/id6813253796 (this page in markdown: same URL + `.md`)
- Developer: [KAZE Application](https://appshunter.io/developer/473675246)
- Category: Utilities, Productivity
- Price: Free
- Age rating: 4+
- Requires: iOS 15.0 · 8 MB
- Languages: American English
- Released: 2026-09-23
- Data updated: 2026-10-13

## What is EL tools?

All the everyday calculations for electrical design, in one app.

When you're designing a circuit, small questions keep coming up:
"Will this resistor pair give me the voltage I need?"
"What's the rise time of this RC circuit?"
"What do three resistors in parallel add up to?"
"Where is the cutoff frequency of this filter?"
"Which resistors give this amplifier a gain of 10?"
"What is 0x3F8 in binary?"

Too small to open a spreadsheet, but you want the answer right now.
EL tools is a practical calculator for electrical design that lets you check these things quickly on your phone.

■ Voltage Divider
Enter the input voltage and target output voltage, choose a standard resistor series (E6/E12/E24/E48), and instantly find the R1/R2 combinations closest to your target.
The min/typ/max output voltage is shown for each combination, taking resistor tolerance (and input voltage tolerance) into account.
See not just the ideal voltage, but the real range you can expect with actual component tolerances.
Useful for power supplies, voltage references, ADC inputs, and other divider designs.

■ RC Step Response
Calculate the time constant τ = RC from the resistance and capacitance.
View the rise (charge) or fall (discharge) curve as a graph, and check the voltage at any elapsed time with a slider.
Handy for early-stage work on reset circuits, delay circuits, smoothing circuits, and switching circuits.

■ Combined Resistance
Supports series and parallel connections.
Calculate the nominal, minimum, and maximum combined resistance from up to three resistor values and their tolerances.
Great when you want to build a target value from resistors you have on hand, or check the result including tolerance.

■ LCR Filter
Calculate filter characteristics from R, L, and C values.
For a 1st-order RC low-pass filter, see the time constant and cutoff frequency. For a 2nd-order series RLC filter, see the cutoff frequency and damping ratio.
The frequency response is shown as a Bode plot, so you can understand the filter's behavior at a glance, not just as numbers.

■ Op-Amp Gain
Choose an inverting or non-inverting amplifier, enter the target gain, and find the Rf/Rg combinations from a standard resistor series (E6/E12/E24/E48) that come closest.
The min/typ/max gain is shown for each combination, taking resistor tolerance into account. A circuit diagram shows where each resistor goes.

■ Programmer Calculator
Convert values between HEX, DEC, OCT, and BIN at a glance.
Tap individual bits to toggle them, and choose the word size (8/16/32/64-bit) and signed (two's complement) or unsigned.
Run bitwise operations (AND, OR, XOR, NAND, NOR, NOT, shifts, rotates) and arithmetic, then feed the result back in to keep going.
Handy for register settings, bit masks, and decoding communication data.

■ Useful for
- Checking values while designing circuits
- Choosing resistor and capacitor values
- Designing voltage dividers for power circuits
- Checking RC delay times
- Working out series/parallel resistor combinations
- Checking filter cutoff frequencies
- Choosing gain resistors for op-amp circuits
- Working with register values and bit masks in firmware
- Quick calculations during prototyping and debugging
- Electronics hobby projects and learning circuits

Quick answers for those "let me just calculate this" moments.
Not complex enough for a full simulation, but you still want the result on the spot.
EL tools supports your day-to-day electrical design work with simple, straightforward controls.

## Is EL tools safe?

Not enough ratings yet to assess EL tools.

## Is EL tools legit?

EL tools: Circuit Calculator appears legitimate, with a few gaps. The AppsHunter Legitimacy Score for EL tools is 75 out of 100 points across 7 verification signals from App Store and developer data.


## Version history (last 4 releases)

### 1.3 — 2026-10-06

- New: Op-Amp Gain. Find standard resistor pairs (E6–E48) for a target gain in inverting and non-inverting amplifiers.
- New: Programmer Calculator. Convert between HEX, DEC, OCT, and BIN, toggle bits, and run bitwise operations (8–64-bit, signed or unsigned).

### 1.2 — 2026-10-02

- Added English language support. The app now follows your device language (Japanese or English).
- Fixed input fields overflowing on narrow screens.

### 1.1 — 2026-09-24

・タブのアイコンとデザインを一新しました。機能ごとに色分けし、画面下に浮かぶ新しいタブバーになりました。
・一部の画面でスクロールすると、画面全体がずれてしまう不具合を修正しました。
・数値を入力した後、画面が拡大・ずれたままになることがある不具合を修正しました。
・タブを切り替えたときに、画面の先頭から表示されるようにしました。
・画面の小さい機種やiPadで、画面下部の内容が広告に隠れないよう調整しました。

### 1.0 — 2026-09-23

No release notes.

## More apps by KAZE Application

- [Knit - knitting counter](https://appshunter.io/ios/app/knit-knitting-counter/id473675243)
- [Tap and Match](https://appshunter.io/ios/app/tap-and-match/id899115852)
- [Knit2 - knitting counter](https://appshunter.io/ios/app/knit2-knitting-counter/id1512656007)

All apps by KAZE Application: https://appshunter.io/developer/473675246

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*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 2026-10-13.*