"Very useful "by MakerMaker
Incredibly handy for anyone working in electronics. Perfect for engineers and non-engineers alike.

"Just what this hobbyist needs" by JoshuaUnwin
I love the clean look and focused tools in this app. It has earned a spot on my first home screen...

Circuit Playground simplifies electronics reference & calculation so you can have more fun hacking, making, & building your projects! This app is designed for both iPhone and iPad.

• Decipher resistor & capacitor codes with ease
• Calculate power, resistance, current, and voltage with the Ohm's Law & Power Calc modules
• Quickly convert between decimal, hexadecimal, binary or even ASCII characters
• Calculate values for multiple resistors or capacitors in series & parallel configurations
• Store, search, and view PDF datasheets
• Access exclusive sneak peaks, deals & discounts at Adafruit Industries

All that, plus updates with additional features & enhancements - MANY NEW CALCULATORS AND TOOLS being added! Not on iOS? An Android version is in the works :) For now, if you'd like to support a cool Android app and developer check out ElectroDroid. Please scroll down here and watch the HD video below about Circuit Playground and check out the screen shots!

Circuit Playground - Made with love by Adafruit, Collin Cunningham, Limor Fried, Daigo Kawasaki, Mosfet and Phillip Torrone

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We also have a paper tool :) We're excited to share this Resistor Helper you can download and make yourself. It's the newest tool in our Circuit Playground family-- when you can't get to your iPhone or iPad, use paper! One side helps you read 4-band types and the other side takes care of 5-band types. The Resistor Helper is on Thingiverse as a PDF (with Illustrator editability preserved). Designed by Adafruit with Matthew Borgatti. You can also grab the PDF on github. Use and enjoy! Tutorial also on Instructables and Make: Projects (blog here).