ElectroDroid is a simple and powerful collection of electronics tools and references. 
This is the free version which contains ads; you can also buy from the Market 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 decoder (3-6 bands); 
• SMD Resistor Code; 
• Inductor color code decoder; 
• Ohm’s law calculator; 
• Reactance/Resonance calculator; 
• Voltage divider; 
• Resistors ratio value/series/parallel; 
• Capacitor charge calculation; 
• Operational amplifier; 
• LED resistor calculator; 
• Adjustable voltage regulator/LM317 calculator; 
• Heat dissipation; 
• Battery Life calculator; 
• Inductor design tool; 
• Voltage Drop calculator; 
• PCB Trace Width calculator; 
• Simple Filters calculator; 
• NE555 calculator; 
• Power Calculator; 
• Decibel Converter; 
• Frequency Converter; 
• Analog-Digital Converter; 
• Y-Δ Transformation; 
• Port pin-out (USB Serial Parallel Ethernet RJ SCART DVI HDMI S-Video VGA VESA Display Port FireWire Jack RCA Audio DIN connector XLR/DMX ATX Power PC peripheral connectors EIDE/ATA SATA PS/2-AT MIDI/Game port Apple 30-pin Apple Lightning connector PDMI OBD-II 25-pair phone cable color code Color Code for Fiber Optic Cables MIDI connector ISO connector for car audio Arduino pin-outs); 
• Resources (USB specification Resistivity table Table of standard resistors and capacitors Capacitor marking codes AWG and SWG Wire size Ampacity Table Symbols and Abbreviations Circuit Schematic Symbols SI Units prefixes Battery info Boolean logic gate and algebra Theorems 7400 info and pinout ASCII codes Batteries list Coin Batteries 78xx IC ChipDB IC pinouts Switch Information Decibel Table PIC ICSP/AVR ISP SMD Package Size Radio frequencies); 
• Full support for EIA resistor series for all calculators; 
...and more to come! 
 
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. 
Electrodroid PRO link: https://play.google.com/store/apps/details?id=it.android.demi.elettronica.pro 
 
For FAQ and full change-log visit http://electrodroid.it