Electronics Engineer Helper26.09.2

Digital toolbox for electronics engineers and electricians. Calculators and references for beginners and professionals - for work, study, DIY, and repair. Used by over 100,000 users. Completely ad-free.

Included tools:
. Datasheet search
. Equivalent parts search (cross reference for transistors, diodes and ICs)
. Resistor color and digit marking (4, 5 and 6 band color code; 2 symbols, 3/4 digit and EIA-96 code SMD resistors code)
. Electronic schematic symbols (IEC 60617, IEEE 315 and GOST standards)
. Pinouts of connectors and interfaces (USB, HDMI, DisplayPort, DVI, VGA, Thunderbolt, Apple Lightning and 30-pin, SATA, PCI Express and M.2, Ethernet RJ45 with PoE, RJ11/RJ14/RJ25, RS-232/422/485, IEEE 1394 FireWire, ATX, computer fans, SD card, audio jack, RCA, MIDI, XLR, PS/2, D-sub, SMEMA)
. Pinouts of boards and microcontrollers (Raspberry Pi and Pico, Arduino, ESP32, ESP8266, STM32 Nucleo, Teensy, Orange Pi, RADXA Rock Pi, LubanCat, Flipper Zero, ATmega and ATtiny)
. Ohm's law calculator
. AWG converter (wire diameter, cross-section area, resistance and maximum current)
. Resistor for LED
. Voltage divider
. Wheatstone bridge (output voltage or unknown resistance, current and power of every arm)
. Capacitor code
. Capacitor markings
. Capacitor ESR tables
. Frequency response curve calculation of passive filters (RC, RL, RLC, LC)
. Inductor color code
. Air-core coil calculator (inductance or number of turns of a single-layer solenoid)
. Ideal transformer (winding turns, voltages and currents)
. Linear current regulator
. SMD packages list
. Reactance
. PCB trace resistance
. Active, apparent and reactive power
. RMS converter (peak, RMS and peak-to-peak values for seven waveform shapes)
. 555 waveform generator
. Operational amplifiers
. RLC circuit
. Number conversion
. Unit converter
. Cable voltage drop
. Battery life (runtime of a battery pack, with discharge curve)
. NTC thermistor resistance
. Logic gates
. RC circuit
. Decibels calculator
. 25-pair cable color code
. Fuse color marking

Additionally, by purchasing the PRO version of the app, you will get access to additional tools:
. SMD components marking codes
. Diodes color code (Pro Electron, JEDEC and JIS-C-7012 standards)
. Linear voltage regulator
. Resistor value to color or SMD code marking converter
. Voltage rectifier
. Series or parallel electrical components' connection calculator
. Diode voltage drop
. Minimum PCB trace width
. Analog to digital conversion
. Attenuators
. 4-20 mA signal converter
. Thermocouple calculator
. Resistance thermometer
. Buck switching voltage regulator
. Wire resistance
. Zener diode regulator (Zener diode and series resistor selection from a catalogue of 438 parts)
. Load cell (bridge output voltage to weight, force, pressure or torque)
. BJT voltage divider biasing
. Transformer turns per volt (from core area, flux density and frequency)
. Junction temperature (with or without a heatsink, power derating curve)
. Solar string dimensioning (minimum voltage and current ratings for a PV array)
. Solar cable and fuse selection (NEC and IEC rules)
. 555 astable generator with variable duty cycle
. NTC thermistor in a voltage divider and with an ADC input

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Version History - 555 monostable calculator. Finds the timing resistor, capacitor or output pulse duration of a one-shot 555 circuit from the other two.
- New pinouts: OBD-II, 555, LM358, LM741, LM393, TL072, LM386.

Big thank you to everybody who subscribed or purchased the PRO version. Your support helps to make this app even better. If you like this app, please rate it and leave a review.
Regards,
Rostyslav 26.09.2 Sep 23 - Optimizations for iOS 27.
- Resistive bridge calculator. Finds the output voltage of a Wheatstone bridge, or an unknown resistance in one of its arms, from the excitation voltage and the other resistors.
- [PRO] Load cell calculator. Converts the output voltage of a load cell into weight, force, pressure or torque, and reports the excitation current and power.
- [PRO] Zener regulator calculator. Selects a Zener diode and a series resistor for the entered output voltage, supply voltage range and load current range, using a built-in catalogue of 438 parts.

Big thank you to everybody who subscribed or purchased the PRO version. Your support helps to make this app even better. If you like this app, please rate it and leave a review.
Regards,
Rostyslav 26.09 Sep 15 - [PRO] Solar string dimensioning calculator. Determines the minimum voltage and current ratings a charge controller or inverter needs for a PV array, from the panel specs, temperature coefficients and site temperature extremes.
- [PRO] Solar cable and fuse selection calculator. Picks the conductor sizes, string fuse and disconnect ratings for a PV array under NEC or IEC rules.
- RMS Converter. Converts between peak, RMS and peak-to-peak voltage or current for seven waveform shapes, and reports the crest factor and average value of each.
- New pinouts: Ethernet PoE, ATmega328P, ATtiny85, ATtiny84A, ATmega32U4, ATmega4809.

Big thank you to everybody who subscribed or purchased the PRO version. Your support helps to make this app even better. If you like this app, please rate it and leave a review.
Regards,
Rostyslav 26.08 Aug 18 - [PRO] Junction temperature calculator. Finds the junction temperature or dissipated power from ambient temperature and thermal resistances, with or without a heatsink, and plots the power derating curve.
- New pinouts: SMEMA, two RS-485 variants, and RJ11/RJ14/RJ25.
- Area and volume units in Unit Converter.
- Additional sources for datasheet and equivalent parts search.

Big thank you to everybody who subscribed or purchased the PRO version. Your support helps to make this app even better. If you like this app, please rate it and leave a review.
Regards,
Rostyslav 26.07.2 Jul 19 - Ideal transformer calculator. Finds unknown winding turns, voltages and currents from the turns ratio, or the winding currents from the rated power.
- [PRO] Turns-per-volt calculator. Determines the volts per turn and number of turns for a transformer winding from operating frequency, effective core area and maximum flux density.
- Cable voltage drop calculator displays the formulas used in the calculation.
- Search bar in the tools list.

Big thank you to everybody who subscribed or purchased the PRO version. Your support helps to make this app even better. If you like this app, please rate it and leave a review.
Regards,
Rostyslav 26.07 Jun 22 - Air-core coil calculator. Determines inductance or required number of turns of a single-layer solenoid from former diameter, wire diameter, insulation thickness and gap between turns. Also reports wire and coil length.
- [PRO] BJT voltage divider bias calculator with three modes: voltage and current ratios, target operating point voltages, or a given set of resistors.
- Additional pressure measurement units in Unit Converter.
- This is the last release supporting iOS 16. Please update to a newer iOS version to continue to receive updates.

Big thank you to everybody who subscribed or purchased the PRO version. Your support helps to make this app even better. If you like this app, please rate it and leave a review.
Regards,
Rostyslav 26.06 May 25 In this update:
- Battery life calculator. Estimates runtime of a battery pack from its chemistry, cell configuration, capacity, depth of discharge and load. Advanced mode additionally accounts for internal resistance, C-rate, Peukert exponent and energy conversion efficiency, and plots the discharge curve.
- [PRO] Series and parallel connection calculator now accounts for component tolerance. Select an E-series for each resistor, capacitor or inductor to see the minimum and maximum of the equivalent value. Entered components are also kept between application relaunches.
- [PRO] PCB trace width calculator now also shows the trace cross-section area and the minimum via diameter and barrel area required to carry the same current.
- Unit Converter now supports angle and torque measurements.
Big thank you to everybody who subscribed or purchased the app's PRO version. Your support helps to make this app even better. If you like this app, please rate it and leave a review.
Regards,
Rostyslav 26.05.2 Apr 29 In this update:
- Battery life calculator. Estimates runtime of a battery pack from its chemistry, cell configuration, capacity, depth of discharge and load. Advanced mode additionally accounts for internal resistance, C-rate, Peukert exponent and energy conversion efficiency, and plots the discharge curve.
- [PRO] Series and parallel connection calculator now accounts for component tolerance. Select an E-series for each resistor, capacitor or inductor to see the minimum and maximum of the equivalent value. Entered components are also kept between application relaunches.
- [PRO] PCB trace width calculator now also shows the trace cross-section area and the minimum via diameter and barrel area required to carry the same current.
- Unit Converter now supports angle and torque measurements.
Big thank you to everybody who subscribed or purchased the app's PRO version. Your support helps to make this app even better. If you like this app, please rate it and leave a review.
Regards,
Rostyslav 26.05 Apr 27 In this update:
- Differential amplifier calculator. Solve for any unknown parameter (resistor values, input or output voltages) in a differential op-amp circuit. Calculates inverting and non-inverting gain.
- [PRO] Wire resistance calculator. Determine the DC resistance of a conductor based on its material, cross-section, temperature and length. Supports AWG, IEC 60228 standard sizes, and custom circular or rectangular cross-sections. Also calculates voltage drop and dissipated power.
- Pinouts for Orange Pi 4 Pro and Zero 3 single board computers.
Big thank you to everybody who subscribed or purchased the app's PRO version. Your support helps to make this app even better. If you like this app, please rate it and leave a review.
Regards,
Rostyslav 26.04 Mar 30 In this update:
- Section switch at main menu. It allows to quickly switch between list of all, favorite and recently used calculators.
- [PRO] Ability to add your own SMD components marking codes.
- Updated Reactance Calculator. It is now possible to calculate not only reactance but also capacitance or inductance and frequency.
- [iOS 17+] ESR table shows lower and upper bounds of expected capacitance.
Big thank you to everybody who subscribed or purchased the app's PRO version. Your support helps to make this app even better. If you like this app, please rate it and leave a review.
Regards,
Rostyslav 26.03 Mar 11 In this update:
- [PRO] Square root scale type in 4-20 mA current loop calculator.
- Color code tool for decoding marking of fuses.
- Ability to edit individual bits in Number Converter.
Big thank you to everybody who subscribed or purchased the app's PRO version. Your support helps to make this app even better. If you like this app, please rate it and leave a review.
Regards,
Rostyslav 26.02 Feb 17 In this update:
- [PRO] Updated the database of SMD components’ markings. It now stores 518 thousand components and is available without Internet access.
- Updated ESP32 pinouts.
- Capacitor code calculator now additionally displays calculated capacitance with milli, micro, nano and pico prefixes.
- Improved contrast of some elements when a dark color scheme is used.
Big thank you to everybody who subscribed or purchased the app's PRO version. Your support helps to make this app even better. If you like this app, please rate it and leave a review.
Regards,
Rostyslav 26.01 Jan 26 In this update:
- [PRO] Resistor voltage divider calculator for DC buck voltage converter.
- 11 pinouts of PCI Express M.2 interface.
- Search bar in pinouts list screen.
- [PRO] Pt(391)46 and Cu53 resistance temperature detectors.
- RC circuit calculator automatically saves entered values between application relaunches.
- Small change of Ohm's law formula selection wheel.
May all your wishes come true in 2026.
Happy New Year!
Regards,
Rostyslav 25.12 12/31/2025 In this update:
- Apple Shortcuts support. Add frequently used tools to home screen using integration with Apple Shortcuts.
- [PRO] Type L thermocouple.
- [PRO] New types of resistance temperature detectors.
- New SATA pinouts.
- Updated app icon for iOS 26.
Big thank you to everybody who subscribed or purchased the app's PRO version. Your support helps to make this app even better. If you like this app, please rate it and leave a review.
Regards,
Rostyslav 25.11 11/19/2025 In this update:
- [PRO] New amplitude-phase frequency response plot (Nyquist plot) in passive filter editor.
- Ability to turn off display sleep while the app is open in app settings.
- Color code tool for decoding marking of 25-pair cables.
- Vietnamese and Thai localizations.
Big thank you to everybody who subscribed or purchased the app's PRO version. Your support helps to make this app even better. If you like this app, please rate it and leave a review.
Regards,
Rostyslav 25.10 10/10/2025 In this update:
- Passive filter editor now also shows phase response curves. You can also customize the measurement units for better analysis of your filter designs.
- Unit converter now supports kg/cm2 pressure measurements.
Big thank you to everybody who subscribed or purchased the app's PRO version. Your support helps to make this app even better. If you like this app, please rate it and leave a review.
Regards,
Rostyslav 25.08 08/24/2025 In this update:
- Custom LED models. Create and save your own LED specifications with threshold or voltage-current table simulation methods.
Big thank you to everybody who subscribed or purchased the app's PRO version. Your support helps to make this app even better. If you like this app, please rate it and leave a review.
Regards,
Rostyslav 25.07 07/04/2025 In this update:
- [PRO] Platinum RTD calculator.
- Updated the formulas for calculating wire ampacity in the AWG calculator.
Big thank you to everybody who subscribed or purchased the app's PRO version. Your support helps to make this app even better. If you like this app, please rate it and leave a review.
Regards,
Rostyslav 25.05 05/01/2025 In this update:
- [PRO] Ability to specify arbitrary analog signal range bounds in 4-20 mA current loop calculator.
- Ability to sort saved datasheets in library.
- Pinout of IEEE 1394 / FireWire interface.
- Minor update of Raspberry Pi pinouts.
Big thank you to everybody who subscribed or purchased the app's PRO version. Your support helps to make this app even better. If you like this app, please rate it and leave a review.
Regards,
Rostyslav 25.02 02/16/2025 In this update:
- When using iOS 17 or newer, the ESR tables reference of electrolytic capacitors will have an updated look with ability to show ESR values only for specific operating voltages or capacitances.
Big thank you to everybody who subscribed or purchased the app's PRO version. Your support helps to make this app even better. If you like this app, please rate it and leave a review.
Regards,
Rostyslav 25.01 01/13/2025 In this update:
- Pinout of Flipper Zero.
- Fixed error in images of NOT and BUFFER logic gates.
Big thank you to everybody who subscribed or purchased the app's PRO version. Your support helps to make this app even better. If you like this app, please rate it and leave a review.
Regards,
Rostyslav 24.12 12/17/2024 In this update:
- [PRO] Passive Filters calculator shows formulas used to calculate the signal magnitude.
- Ability to add PDF files from external sources to Datasheet Library.
- Fixed alignment of pins depiction in DVI pinouts.
Big thank you to everybody who subscribed or purchased the app's PRO version. Your support helps to make this app even better. If you like this app, please rate it and leave a review.
Regards,
Rostyslav 24.11.3 11/27/2024 In this update:
- When using iOS 18, any list of electronic schematic symbols can be translated into the app's current language.
- Internal stability improvements.
Big thank you to everybody who subscribed or purchased the app's PRO version. Your support helps to make this app even better. If you like this app, please rate it and leave a review.
Regards,
Rostyslav 24.11.2 11/10/2024 In this update:
- When using iOS 18, any list of electronic schematic symbols can be translated into the app's current language.
Big thank you to everybody who subscribed or purchased the app's PRO version. Your support helps to make this app even better. If you like this app, please rate it and leave a review.
Regards,
Rostyslav 24.11 11/10/2024 In this update:
- Pinout of LubanCat 4 single board computer.
- Internal optimizations.
Big thank you to everybody who subscribed or purchased the app's PRO version. Your support helps to make this app even better. If you like this app, please rate it and leave a review.
Regards,
Rostyslav 24.10.2 10/06/2024