Cressall Resistors is usually associated with heavy engineering but the company also has software engineering expertise in-house, the first fruit of which is an iPhone app for solving Ohm's Law.
It has already been downloaded more than a thousand times in less than a month; a very impressive total for a technical app and far in excess of Cressall's own targets.
Ohm's Law is the essential mathematical model that engineers use for mentally mapping out electrical circuits. The brainchild of Peter Duncan, who retired as managing director of Cressall Resistors at the end of 2012, the iPhone app originated as a routine for solving Ohm's Law on his handheld Hewlett Packard programmable scientific calculator. Peter was using it daily and thought it would be useful to other electrical engineers as it allows them to input any two of the key variables of volts, amps, ohms and power, and calculates the other two.
Once the first calculation is solved, an engineer can then change the value of any of the resulting variables, and the app will back-solve all the other variables automatically.
"Peter showed me the program on his calculator and then we worked through the routines to write an app to replicate it," recalls Chris Johnson of Cressall Resistors. "There are several Ohm's Law calculators in the Apple app store at the moment but they clear their data after each operation and you're forced to recalculate every time. With our app you can change any parameter value and keep playing around with it until you come to a satisfactory solution. If you're in any doubt about what you're doing, you can call up a power triangle diagram."
"The Android version is in development now and being ported over. We will extend the language options available too, in partnership with our international agents who have volunteered to give us translations for their home markets. We are expecting to launch German, French and Swedish versions soon."
Chris reveals that the next release on the drawing board for the app is a star-delta calculator for three-phase electric motors, with more ideas over the horizon. Every revision and new language will be offered free as an upgrade. Following the port to Android, Chris anticipates one to Windows Phone, written in Microsoft's own C# programming language.
"When I wrote the iPhone app, I learnt the Objective C and Xcode which it's written in, and although it is a different programming environment, it isn't massively different," Chris continues. "In the case of Android, that is written in Java, which is similar to C#. You cannot just convert an app because the whole paradigm of an Android app is a little different from an iPhone app."
"I believe Android users get annoyed if the app looks like a rehashed iPhone app. They would rather you write it in their design style. If that is what they want to see, you should not try to shoehorn an external design in."
Visit Cressall Resistors at www.cressall.com
This article originally appeared on EE Times Europe.