Electrodoc is a simple and powerful collection of electronics tools and references.
Electrodoc is the new app name of Electrodroid. Same app, with the same and even more features.
This is the free version, which contains ads; you can also buy from the app store the PRO version of the app to support the developer, unlock more features and get rid of the ads.

The app includes:
• Resistor Color Code;
• SMD Resistor Code;
• Inductor Color Code;
• Ohm's Law;
• Reactance/Resonance;
• Filters;
• Voltage divider;
• Resistor Ratio;
• Resistor series/parallel;
• Capacitor series/parallel;
• Capacitor charge;
• Operational Amplifier;
• LED Resistor Calculator;
• Adjustable voltage regulator;
• NE555 Calculator;
• Power dissipation;
• Battery Life calculator;
• Inductor Design Tool;
• Voltage Drop Calculator;
• PCB Trace Width Calculator;
• Power Calculator;
• Frequency Converter;
• Analog-Digital Converter;
• Port pin-out (USB port, Serial port, Parallel port, Ethernet port, Registered Jack, SCART connector, DVI connector, HDMI connector, Display Port, VGA connector, S-Video connector, Jack connector, FireWire connector, RCA connector, Audio DIN connector, XLR and DMX, ATX Power connectors, EIDE/ATA - SATA, PS/2-AT connectors, 25-pair cable color code, Fiber Optic cable color, MIDI connector, Apple Lightning connector, OBD-II Car connector, Car audio ISO connector, Arduino boards);
• Resources (PIC ICSP / AVR ISP, ChipDB (IC pinouts), USB specifications, Resistivity Table, AWG-SWG Wire Size, Ampacity Table, Standard Resistors, Standard Capacitors, Capacitor marking codes, Circuit Schematic symbols, Symbols and Acronyms, SI Units prefixes, ASCII Table, Boolean Logic gates, Switch Information, 78xx IC, Batteries, Coin Batteries, Decibel Table, Radio frequencies);
• Full support for EIA resistor series for all calculators;
...and more to come!

The Pro version doesn't have any ads, and has additional features like new calculators, and more pinouts and resources.
There are also improvements in some calculators (e.g. LED, voltage regulators), extra features in some plugins, and it is possible to sort the lists according to your preferences.
These are the extra calculators and pinouts available at the moment only in the PRO version: Lookup Resistor color by value, Zener Diode Calculator, Y-Δ Transformation, Decibel Converter, RMS Converter, Range Converter, Power Over Ethernet, VESA Connector, PC peripheral connectors, MIDI/Game port, Apple 30-pin connector, PDMI, Trailer connectors, SD card pin-out, SIM/Smart card, Raspberry Pi pin-out, LCD pin-out, GPIB/IEEE-488 pin-out, Thermocouples colors, Arduino boards, JTAG pinouts, BeagleBone boards, SMD Package Sizes, 7400 series IC, PT100 Conversion Table, Fuses color code, Automotive Fuses colors, DIN 47100 color coding, IP marking, World Plugs & Sockets, IEC Connectors, NEMA connectors.

The app has also support for plugins to expand functionality of the application (e.g. PIC and AVR micro-controllers Database, simulators, parts search).

If you like the program, please rate it, and buy the full version to support the development.
Electrodoc Pro link: https://play.google.com/store/apps/details?id=it.android.demi.elettronica.pro

For FAQ and full change-log, visit http://electrodoc.it

Recent changes:
Version 5.0:
• new app name: Electrodroid is now Electrodoc;
• capacitor series/parallel calculator;
• dark theme;
• rewritten large parts of the app;
• optimized layouts;
• new high quality images;
• support for resistors • minimum Android 5 required;
• translation updates;