VansAirForceForums  
Home > VansAirForceForums

- POSTING RULES
- Donate yearly (please).
- Advertise in here!

- Today's Posts | Insert Pics

  #1  
Old 05-26-2019, 06:23 PM
Canadian_JOY Canadian_JOY is offline
 
Join Date: Aug 2007
Location: Ontario, Canada
Posts: 2,088
Default AF2500 Pressure Senders with GRT EIS?

Making a change of equipment... Out with the old, in with the new.
The old... AF2500 engine monitor.
The new... GRT EIS-66R.

I've purchased the GRT oil pressure sensor and fuel pressure sensor (engine has a carb so this is the low pressure sensor) manufactured by VDO. I have to admit I'm totally unimpressed by the method of connecting the VDO fuel pressure transducer to the EIS - a kluge of resistors to get the right range to work with the AUX input. Not exactly my idea of an "aircraft grade" installation.

Has anybody successfully used the AF2500 pressure sensors with the GRT EIS? The AF2500 sensors in question are the small-diameter senders with 3-pin connectors on the end, supplying power and ground from the ACS2002 analog module and piping a 0-10V signal back to the analog module. These are very slick (not to mention expensive) senders - far better quality than the VDO units that GRT supplies.

Thanks for your helpful replies.
Reply With Quote
  #2  
Old 05-26-2019, 06:48 PM
lr172 lr172 is offline
 
Join Date: Oct 2013
Location: Schaumburg, IL
Posts: 4,190
Default

The oil sender is fixed, but all others are done in software vi offsets. I installed transducer style sensors on my EIS system
__________________
N64LR
RV-6A / IO-320, Flying as of 8/2015
RV-10 in progress
Reply With Quote
  #3  
Old 05-26-2019, 08:55 PM
Canadian_JOY Canadian_JOY is offline
 
Join Date: Aug 2007
Location: Ontario, Canada
Posts: 2,088
Default

Thanks for your comments, Larry.

From your comment I understand engine oil pressure is looking for straight resistance to ground, thus the preference for the VDO. I'm wondering if one could just use the signal wire from the AF2500 sensor (I haven't checked to see if the AF2500 oil pressure sensor is just a resistive sensor or if it does anything more fancy with the signal output)?

Which sensors did you use, and how did you wire them? I'm assuming you used the EIS 4.8V sensor excitation provided by the EIS? In the AF2500 the pressure transducers were powered by +5V thus I think the AF2500 was looking for its signal input as a voltage ratio referenced to ground.
Reply With Quote
  #4  
Old 05-27-2019, 04:42 AM
h&jeuropa h&jeuropa is offline
 
Join Date: Jun 2008
Location: Kalamazoo, MI
Posts: 227
Default

As Larry stated, the oil pressure is dedicated to use a VDO resistive sensor.

All the aux inputs can be customized to your application. In the EIS manual there is discussion of Transfer functions. Essentially the EIS assumes that the data stream is in the form of a straight line, y=mx+b. You define y which is the scale factor and b which is offset. You modify them by a factor of 10 to get integer or decimal displays. I have a more detailed discussion I can email you.

In my case the only GRT sensor I use is manifold pressure.

Jim Butcher
Reply With Quote
  #5  
Old 05-27-2019, 06:25 AM
lr172 lr172 is offline
 
Join Date: Oct 2013
Location: Schaumburg, IL
Posts: 4,190
Default

Quote:
Originally Posted by Canadian_JOY View Post
Thanks for your comments, Larry.

From your comment I understand engine oil pressure is looking for straight resistance to ground, thus the preference for the VDO. I'm wondering if one could just use the signal wire from the AF2500 sensor (I haven't checked to see if the AF2500 oil pressure sensor is just a resistive sensor or if it does anything more fancy with the signal output)?

Which sensors did you use, and how did you wire them? I'm assuming you used the EIS 4.8V sensor excitation provided by the EIS? In the AF2500 the pressure transducers were powered by +5V thus I think the AF2500 was looking for its signal input as a voltage ratio referenced to ground.
I used kavlico knock offs for fp and it is powered from the eis 4.8 vec output and the .5 to 4.5 voltage return goes to the aux input. Youneed a bit of math to get the settings right, but no resistors

Op is a non adjustable input, so must use the vdo sensor to get it to read correctly. I dont see how you could use a kavlico for this, as the eis will have an internal pull up and be looking for a resistance to grd. As well as a fixed table for voltage to presssure

The eis box is clever for 80’s technology, but woofully behind by modern standards. It is really forced into the market today by grt refusing to duplicate the functionality in their efis units
__________________
N64LR
RV-6A / IO-320, Flying as of 8/2015
RV-10 in progress

Last edited by lr172 : 05-27-2019 at 06:33 AM.
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -6. The time now is 07:57 AM.


The VAFForums come to you courtesy Delta Romeo, LLC. By viewing and participating in them you agree to build your plane using standardized methods and practices and to fly it safely and in accordance with the laws governing the country you are located in.