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  #1  
Old 02-18-2018, 06:27 PM
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N333M N333M is offline
 
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Default Which analogs instruments to leave in panel. GRT Sport EX install

I am considering which of the old instruments to leave in the panel. Airspeed of course, turn and bank, maybe altimeter..maybe not, if there is room. But I would also like to have a few engine gauges.
My question is, can one run the single signal wire to a resistive element analog gauge, like the fuel levels, or the oil pressure, and to the GRT EIS 4000 together? Will they read correctly?
thanks,
Don
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Old 02-18-2018, 06:42 PM
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Jesse Jesse is offline
 
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What to leave would be determined by your mission and trust in the GRT system. As for engine gauges, I have never tried to run two systems off of one sender, but I am sure some would work and others wouldn?t. The GRT system sometimes uses pull-up voltage to convert a resistance sender into a voltage input, which would likely cause the standard gauges to be unreliable. Having the other instrument connected to the sensor should not change the GRT usability, because you can calibrate the GRT to work with just about any voltage input by adjusting the scale factor and offset to get the accurate value to display on the screen.
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Old 02-18-2018, 09:24 PM
lr172 lr172 is offline
 
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Quote:
Originally Posted by Jesse View Post
What to leave would be determined by your mission and trust in the GRT system. As for engine gauges, I have never tried to run two systems off of one sender, but I am sure some would work and others wouldn?t. The GRT system sometimes uses pull-up voltage to convert a resistance sender into a voltage input, which would likely cause the standard gauges to be unreliable. Having the other instrument connected to the sensor should not change the GRT usability, because you can calibrate the GRT to work with just about any voltage input by adjusting the scale factor and offset to get the accurate value to display on the screen.
With the exception of the oil pressure. They have this hard coded to work with the VDO sensor that they spec/supply. No scale factor/offset available.

Larry
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Old 02-18-2018, 10:56 PM
BobTurner BobTurner is offline
 
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As Jesse said, you can calibrate the GRT to read accurately if, say, the fuel level sensor is loaded by an analog gauge. But, if the analog gauge fails, then the GRT won?t read correctly either. I?d use the panel space for independent, back up flight instruments.
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Old 02-19-2018, 01:54 AM
gasman gasman is offline
 
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Quote:
Originally Posted by N333M View Post
I am considering which of the old instruments to leave in the panel. Airspeed of course, turn and bank, maybe altimeter..maybe not, if there is room. But I would also like to have a few engine gauges.
thanks,
Don
I left the oil pressure gauge and sender as a back-up...... That's the one gauge that would make me get on the ground asap. The senders do have a high failure rate.
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Old 02-19-2018, 06:54 AM
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Default oil press

Gasman,
thats kinda what I was thinking, oil pressure would be nice to have backed up with analog. Did you run the single signal wire from the VDO sender to both you analog gauge AND the EIS? or leave it out of the EIS ?
Don
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Old 02-19-2018, 08:52 AM
flyinga flyinga is offline
 
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If panel room is a consideration, how about an "idiot light" for oil pressure?
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Old 02-19-2018, 10:56 AM
gasman gasman is offline
 
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Quote:
Originally Posted by N333M View Post
Gasman,
thats kinda what I was thinking, oil pressure would be nice to have backed up with analog. Did you run the single signal wire from the VDO sender to both you analog gauge AND the EIS? or leave it out of the EIS ?
Don
Already had Van's OP gauge and sender mounted on top brace. Just installed a "T" and added VDO sender for MGL Xtreme.

The only sender that worked double was Van's tach sending unit works his tach and the Xtreme tach with no problem.

The back-up oil pressure gauge is not for EMS failure...... it is for sender failure which is way more common, and could cause you a lot of stress as you fly along looking for a place to land before the motor fails. A look at the back-up oil gauge would tell you the severity of the problem.
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Last edited by gasman : 02-20-2018 at 09:23 AM.
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  #9  
Old 02-19-2018, 02:43 PM
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uk_figs uk_figs is offline
 
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I built mine with backup airspeed and altimeter (early dual dynon glass) and I also wired the oil pressure sensor to a master caution light in the panel.

I have had one instance where the glass went dark due to overheating on the way to Vettermans in South Dakota and the analogue instruments with the 796 worked out fine.

It took me a while to get used to looking at the glass as primary but I do like having the backups and I do try to keep the analogue altimeter in sync.

Some of my buddies decided on no backup analogue instruments so that they had to concentrate on the glass display and were not distracted, just different philosophies.

I do have to say that other than the one overheat situation (I now blow air around the back of the panel, RV-7 slider) the dynons have been rock solid since 2008 so reliability does not seem to be a big issue with glass cockpits.

Your call really.
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Old 02-20-2018, 04:25 AM
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I have zero analog engine instruments to duplicate EIS 4000 data. My thinking is that an electrical failure and loss of EIS data is one of two things: not critical since my engine is not electrically dependant or critical because I have lost other functions unrelated to engine indication. In neither case do I need analog engine instruments.

In regards to analog backup flight instruments, that is a personal choice. For VFR, none. For IFR it depends on your skill at flying partial panel. It can be done with as little as airspeed, altimeter and turn and bank. In my case, I chose airspeed, altimeter, Trutrac horizon, whiskey compass. And the answer is that they DID save my bacon once when the EFIS went TU in the soup. The event was almost a non-issue with the backups.
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