4-20mA Aerospace Widgets - a technical guide

Updated January 2023 by Chris Rand

There are many types of widgets, even in the aerospace sector, but 4-20mA aerospace widgets deserve special consideration because of their widespread usage. First coined in 2009, the term "4-20mA aerospace widget" does not appear to have been around much until then, as this Google search makes clear.

What is a 4-20mA Aerospace Widget?

The 4-20mA Aerospace Widget is a small device for measuring relevant parameters in aircraft, using the 4-20mA current loop for its control and communications. The component can be obtained in a range of sizes and ratings, and is based on customised transducer technology developed for virtual applications.

Typical 4-20 mA Aerospace Widget schematic diagram

Why use 4-20mA for widgets on aircraft?

The 4-20mA current loop is well documented and is employed throughout industry. Widgets, of course, have been a vital component of commercial and military aircraft for many years, although it's not known which manufacturer first thought of powering them through a 4-20mA system. Here at the Blue Widget Company [1] in the UK we took up the concept enthusiastically long ago, although, as mentioned, nobody thought to call them "4-20mA aerospace widgets" until much more recently.


Aerospace is used to refer to the aircraft and space industries, including the research, design, manufacturing, operation, and maintainance of aeroplanes, spaceships and things like that.

4-20mA is a simple two-wire current loop system used in transducer technology a lot.

Widgets can refer to anything, particularly those things which you can't remember the name of.


[1] The Blue Widget Company is a virtual organisation which is one of many that ought to have its own website really.


Yes, this page is really just an example of how straightforward it is to build something which will be considered an authority on its subject. Albeit a rather random, and indeed made-up, subject.