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Analog instrumentation                                                   

In the second stage of completing the cockpit I always wanted to replace the monitors with analog instrumentation. At first I wanted to use real instruments. But the golden age of finding these instruments is long gone and if you find one it will cost you a fortune. I decided to put this project back in the drawer. But most unexpected there appeared a alternative.

In connection to the visit of ITEC 2003, this is a professional exhibition of all what has to do with Simulation. I came in contact with TRC development of the Netherlands.
This company constructs in the first instance a cockpit panel trainer of a cessna 172 for starting pilots and pilot training schools. But they also have a division called Simkits who sell analog instruments in kit form. This means that the instruments are put together like a kind of a model kit, with al kinds of plastic and metal parts. Included is also a step by step construction plan. All the instruments are power by servo motors and connected to the CCU (Central Control Unit). This CCU is connected via the USB connector to the PC. The software can be downloaded on there web site. You also need FSUIPC to retract the data from FS. Before connecting the instruments to FS you need to calibrate them first. There for you also need a special program also downloadable and to be follow step by step.
At first I was a little bit afraid of the fact that my Visual Basic program who also uses FSUIPC would interfere with the software of the CCU who uses the same FSUIPC to retract information. Therefore I first e-mailed the contact person of them but unfortunately I never got any reply. I wasn't that happy with it. But a man must take a gamble from time to time and dare to invest. So I decided to place a trail order of 1 CCU and 1 universal instrument (airspeed indicator).
After a few days I received a packing delivered by ABX. It was packed with care and each part was well protected. The next day I started assembling the instrument. What was not so difficult at all.
After installing the necessary programs and connecting the CCU to an old power supply of an old PC I could start testing. Of course I first calibrated the instrument and Yes it worked from the first time. Then the second test, how would it react with FS. I first started the connection program and after that FS. I selected the cessna to see if the instruments on the monitor reacted like the build instrument. This seemed to work also only the needle on the instrument didn't react as vigorous as the needle on the monitor when you flew in turbulent weather but in normal conditions it followed exactly the same.
Than came the most exciting moment, would it also work together with my own cockpit management program. You could feel the tension in the air, my hart was beating fast and with clammy hands I started up the program. The first motor was started and the the moment of trued came. I moved the throttle forward and the speed increased and wonder by wonder the needle of the instrument started to move. I took of and made a short flight. Everything stayed on running. The two programs didn't interfere with one another and each of them did his own part of the work. So after all it seemed a right gamble. A few days later I have put in a new order for a attitude indicator, altitude indicator,turn & bank indicator, vertical speed indicator, heading indicator, VOR 1, VOR 2  and ADF.A week later the package was delivered.
I then started with the construction of the attitude indicator. The construction of this instrument was also not to difficult. All except for 1 detail it fitted perfectly. They just put in a to small strap to attach the servo on the instrument. This problem was soon overcome. After a quick test this instrument seemed to work well.


The next instrument was the altimeter.
This instrument is the hardest to put together with all the complex gear works inside. You have three indicators for the height 100, 1000, 10.000 feed and you also have the air pressure scale. Just like the other instruments I followed the the instruction manuel but when I came to the part of the gearbox I got stuck. I couldn't put the pieces together in the way they described. I then took it all back apart end assembled it in a simpler way of my own. All this has taken me day to put it all together again. Than the first test. The pointers of the altitude indicator worked well. But the servo of the air pressure scale didn't work at all. I looked around to see if Murphy hadn't anything to do with it. I tried out almost everything but without any result. I then send an e-mail to the helpdesk with a detailed report on what didn't work. I received a reply the same day but without any advise or solution of my problem. They only referred to the instruction manuel and further nothing. It didn't bring me a passe further toward the solution. I then decided to go on with the construction of the other instruments to see if there were also other instruments who didn't work properly. Finally also the VOR1 and VOR2 didn't function completely. Always 1 servo didn't receive any signal. I reported this again to the helpdesk. I also requested to make an appointment with them to look in to this problem. Unfortunately they would not go in on my request because they were not able to receive customers, they said. The only thing they suggested was to send them the not working instruments together with the CCU. They would look in to it and fix the problem. Most likely the problem was the CCU. I then wrapped everything nicely and posted it back to them.
After a good week I received everything back together with a new CCU. After connecting everything I started to test it thoroughly again and I discovered that there were still things not working. They had replaced the CCU what solved the problem with the air pressure scale and the vertical needle of the VOR1 but the ADF and VOR 2 together with the Altimeter didn't still work properly. The needles jumped up down like a jo jo. I contacted them again and told them about the problem and asked them what to do next. The next day I started looking myself for the reason of these mistakes.
And I found them. By a mistake in there instruction manuel I put the Piher potentiometers of the different instruments in the opposite position so the values that were send back weren't correct. A small detail with big consequences. I mailed them back with a detailed report of the mistake together with some photos. After this mail they saw that the mistake was there's and they invited me for a visit to look for the problem with the VOR2.
On Julie 21th I went to Rotterdam with the instruments and the control unit. After a quick test they discovered that the mall function wasn't caused by a fault in the CCU but the servo wasn't connected to right connector. Again a mistake in the instruction manuel. The problem was very easily solved. I'm very glade this chapter ended well and that all is working properly now.

Now I can start thinking on mounting everything on a aluminum panel. The CCU will be build in a box of Plexiglas to cover it from dust. So the second part is earlier finished than the first. How I assembled the front panel, I will inform you in detail in the next article.




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© Verley Jan 2007-2017original text from 2003