iPhone Screenshots


A handy engineering utility that solves for voltages or resistor values in a common voltage divider circuit. Enter three terms (out of Vin, Vout, R1 or R2) and this app will solve for the fourth term automatically. The resistor picker will only let you pick from actual resistor values that exist. It's a great time saving tool for quickly selecting resistor values in a switching power supply design or any other circuit that incorporates a voltage divider.

When solving for a voltage, select two resistor values and one of the voltages. The remaining voltage will be displayed automatically. The max and min possible voltages will also be displayed based on the resistor tolerances. The current and power through the divider will be displayed at the bottom of the screen.

When solving for a resistor value, select two voltages and one resistor value. The remaining resistor value will be displayed in yellow. This is an ideal value. Use the resistor picker to select an actual resistor value close to that ideal value. You can then tell the app to solve for Vin or Vout to see if the resulting voltage meets your design requirements.

Want to see something cool? Select any two resistor values then enter this special voltage for Vin: 4696 :-)

What’s New

Version 1.0.2

Updated to run on latest version of iOS.

Special shout out to John McClelland. Thanks for the motivation :-)

Ratings and Reviews

3.5 out of 5
2 Ratings

2 Ratings


more than a solver

I design power supplies so I often have to calculate the feedback voltage divider. Sure, it is easy enough in a calculator but having all the standard 1% and 5% values in this app makes things easy. I normally have to solve for a R value and then look up the closest real 1% value. Then I solve to find my actual output voltage only to find that it isn't close enough so I have to do it again with another R value. With this App I can just have the it solve for the ideal value and then the resistor selction wheel shows me the closes real value resistors. I can easily see what my output voltage would be using those values.

Pros: works well and looks pretty good. It is cool to see the color bands on the resistors change with value
Cons: On my 2G iPhone the resistors had black splotches on them. All is good with my iPhone4 (I think 3G and up don't have this problem).

BLVD Drinker ,

Does what it says, nothing more.

Nice user friendly interface. Would be handy if it displayed power dissipation of each resistor, then displayed minimum resistor package size (i.e. 0603 SMT for <0.1W, etc.).

Jason J. Gullickson ,

Simply Beautiful

Elegant in form and function, so fun to use it makes me want to start a new electronics project just to play with it.

We need more apps like this, I'd love one for playing with transistors or analog ic's.


Ditty Labs, LLC
898 KB

Requires iOS 10.0 or later. Compatible with iPhone, iPad, and iPod touch.



Age Rating


  • Family Sharing

    With Family Sharing set up, up to six family members can use this app.

More By This Developer

You May Also Like