Voltage divider
From an input voltage and a target voltage, find resistor combinations close to the target in the E6/E12/E24/E48 standard series. See the minimum, typical and maximum output voltage with resistor tolerance taken into account.
ELECTRICAL DESIGN TOOL
EL tools: Circuit Calculator
The calculations you need in electrical design, in one app. Check a quick calculation on the spot while you work. (Japanese name: EL tools：電気設計便利ツール)
- Free
- Contains ads
- iOS 15.0+
- iPhone / iPad
- 4+
SCREENSHOTS
Screenshots
iPhone
iPad
FEATURES
Key features
RC transient response
Calculate the time constant τ = RC from resistance and capacitance. See the rise and fall as a graph, and check the voltage at any elapsed time with the slider.
Combined resistance
Supports series and parallel connections. Calculates the nominal, minimum and maximum combined resistance from several resistances and their tolerances.
LCR filter
Calculate filter characteristics from R, L and C values. Check the time constant and cutoff frequency, with the frequency response shown as a graph.
Op-amp gain
From a target gain for an inverting or non-inverting amplifier, find Rf/Rg combinations close to the target in the E6/E12/E24/E48 standard series. See the minimum, typical and maximum gain with resistor tolerance taken into account, and a circuit diagram shows where each resistor goes.
Programmer calculator
See and convert values in HEX, DEC, OCT and BIN at once. Tap bits to toggle them, and choose the word size (8–64-bit) and signed or unsigned. Supports bitwise operations such as AND, OR and XOR, shifts and rotates, and arithmetic.
USE CASES
Handy for
Supports everyday checks that don’t call for a full simulation.
- Checking values while designing circuits
- Choosing resistor and capacitor values
- Voltage divider design for power circuits
- Checking RC delay times
- Comparing series and parallel resistor combinations
- Checking filter cutoff frequencies
- Choosing gain resistors for op-amp circuits
- Working with register values and bit masks
- Quick calculations during prototyping and debugging
- Learning electronics and circuits
HOW TO USE
How to use
The basic flow.
Choose a calculation
Pick “Divider”, “Transient”, “Combined R”, “LCR Filter”, “Op-Amp” or “Programmer” from the tabs at the bottom.
Enter values
Enter values such as voltage, resistance, capacitance or target gain. The programmer calculator has its own keypad in the app.
Check the result
The results and graphs appear right away.
FAQ
FAQ
Does it cost anything?
EL tools: Circuit Calculator is free to use.
Which devices and OS versions are supported?
iPhone and iPad running iOS 15.0 or later.
What language is the app in?
The app is available in English and Japanese, and switches automatically to match your device’s language setting (Ver.1.2 and later).
Do the ads appear?
Yes, ads are shown. We use Google AdMob to serve ads. For how information related to ads is handled, please see the Privacy Policy.
Where can I report a problem or send a request?
Please use the contact form and choose “EL tools: Circuit Calculator” as the app.
UPDATE HISTORY
Update history
- Ver.1.3
- 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).
- Ver.1.2
- Added English language support. The app now follows your device language (Japanese or English).
- Fixed input fields overflowing on narrow screens.
- Ver.1.1
- Redesigned the tab icons and design. Each function now has its own color, on a new tab bar that floats at the bottom of the screen.
- Fixed an issue where scrolling on some screens shifted the whole screen.
- Fixed an issue where the screen could stay zoomed or shifted after entering a number.
- Screens now start from the top when you switch tabs.
- On smaller devices and iPad, adjusted the layout so content at the bottom of the screen is not hidden by ads.
- Ver.1.0
- Initial release
Try EL tools: Circuit Calculator
Free to download.