You can build them... Really! 

There are several possible approaches, plus a surprising amount of surplus goodies that can be used to help keep the cost under control. The picture below shows an assortment of homemade instruments based variously on air-core movements, stepping motors and servos.

Air-core movements are the basis for most contemporary automotive and marine gauges, speedometers and tachometers.  While new air-core movements are not available at reasonable cost, you may run across them in junkyards and, as they are fundamentally simple devices, they can be made from scratch by the enterprising hobbyist.

Stepping motors are used, it seems, in just about everything these days.  Clever mechanical fabrication people have figured out how to make them out of inexpensive (though quite precise) stamped sheet metal.  They are a natural for being controlled by micro controllers with, in some cases, only the most simple of power buffers.  As a result, they turn up in scanners, printers, disk drives, fax machines and so on.  This of course means they also turn up on the surplus market for very attractive prices.  Stepping motors can be used to make simple gauges, but their relatively high torque make they especially attractive for instruments with more complex, heavy mechanisms like attitude indicators.

A servo is really any sort of arrangement that uses feedback to actively track and adjust some desired parameter.  One particularly prevalent application useful to us is the RC servo.  Basically a small plastic or metal box with wires coming out one end and a rotating shaft coming out the other, the RC servo is a combination of gearing, motor, electronics and packaging presented at a great price.  It's a snap to control with a micro controller, and is easily applied to such projects as simulated glide slope localizers and VOR course deviation Indicators.

The D'Arsonval movement is the basic meter movement used in audio signal level meters and voltmeters before LEDs and LCDs became popular.  Actually, these movements still see general aviation use today in mechanical localizers and CDIs.  Meters utilizing D'Arsonval movements are available both new and surplus, and can be converted to simulator use with modest effort.

The simulated instruments pictured above and in the following pages are project prototypes for the book Building Simulated Aircraft Instrumentation. 

I gave a presentation at the AVSIM 2005 conference about building simulated aircraft instruments. You can download the handout from my talk here (PDF).

It's possible that I'm not as smart as I think I am. (Occasionally, I have moments when I know this to be true. Fortunately the feeling passes quickly.) Although I have tried to make this information as accurate as I can, it is not only possible, but also quite likely, that errors lurk within. I cannot and do not warrant these pages to be error free and correct. Further I accept no liability for the use of this information (or misinformation). If, after reading this, you are still interested, please be aware that the contents of this site are protected by copyright (copyright © 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009 by John M. Powell). Nonetheless, you may copy this material subject to these three conditions: (1) the copyright notice is copied and presented along with the material, (2) the copy is used for non-commercial purposes, and (3) the source of the material is properly credited. And of course, you may link to this page.