analog gauges

[gspannelljr]

I have several gauges that are analog that I wan to use. Turn/bank, rate of climb, airspeed, etc. I could convert them to servos but they work just fine as is. My question is, is there a simple way to control them? Everything I am seeing is PWM for servos. I just don't want to make extra work but it looks like I have no choice. Anybody know of any alternative ways to drive these gauges?Thanks!!!

[Mike.Powell]

I don't think there is a simple way to use them as is. The turn and bank indicator almost certainly has a gyro in it. Using it unmodified requires tweaking the laws of physics, probably more effort than it's worth. If the RoC is a remote remoting head you can possibly interface to it, but without documentation, that's a chore. If it's a self contained, barometric unit (like a general aviation VSI) you can build a computer controlled pressure unit to feed it, but this will not activate the inertial lead aspect of it. An air pressure sensing ASI will respond to the same sort of controlled pressure unit, but accurate control of the pressure is necessary for accurate display of air speed. Do-able, but not simple.

Some real aircraft instruments you can use as-is, but some are just not worth the effort. Commercial and military instruments IMHO tend to be the "easiest" to use as-is because there are enough people trying to do so that we are now seeing documentation appear for them. Still, "easy" is a relative term. There is a significant hurtle to jump to get started. While some basic gauges like EGT and tachs can be simply controlled, the really interesting ones like the ADI and HSI, are complex and take a non trivial effort for success.

Although you haven't mentioned the specifics of the instruments you have, I'll go ahead and suggest that if you want realistic looking instruments that work with your simulator, either convert your instruments or use them as reference items and build sim instruments from scratch.

[gspannelljr]

Thank you Mike for the information. Trying to figure out how to do this has stalled my flight sim project. I was trying to plan out all my controls and couldn't get past the analo gauges. You solved my problem. I will convert them to servos and be done with it. Thanks again. You are a BIG help!

[Tripacer]

Mike won't blow hos own whistle, but I will. Hes has written and published two books on the subject of building instruments for filght simulators. You should check them out, they make excellent resources for all aspect of this portion of our hobby. I have completed five (5) instruments so far and am very satisfied with the results.
Some of the instruments that you mentioned might be ideslly suited to using servos movement source. However, some instruments need 360 degrees or more rotation, a compass, for example. These instruments make better use of stepper motors.
My instruments are all built from scratch, having a source of "dead" instruments might supply the faces for the mechanical back ends. If you have an economical source, lets us know. I would like to tinker with one. After all the face is what you see in the cockpit.
Tripacer

[gspannelljr]

tripacer, I have already ordered the books. I agree with you on the values of them. I solved my issue with the gauges pretty easily. I figured why tear apart a working gauge to intall a servo? Whynot use the servo external to the gauge to drive a potentiometer that will control the voltage to the gauge? This is faster to build, requires no hacking or modification of the gauge and is really easy! For the gauges that go + and - scale, like the rate of climb, I ganged 2 pots together and used + and -voltages to drive each direction of the gauge. The transition from + to - is seamless and works great! The compass type gauge will have to be converted to a steper motor. It currently has a resolver in it.
I work in the automotive industry and am working on a source for good gauges that are conversion freindly. I will CERTAINLY let you guys know if I find a good source etc.Thanks for the help.