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  #11  
Old 10-09-2019, 03:21 AM
DeeCee 57's Avatar
DeeCee 57 DeeCee 57 is offline
 
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thanks for the write-up and pics Gary.
I have the same set-up waiting for an end-of-the-season (rather call that a slow-down...) install, presently sporting a single G5.
Though also on my parts to be installed pile a Davtron OAT and, lucky me, a GNX375 and GAD29...

Wonder what it would take to have an AP function, 2 servos and a control panel? Anyway to go without the control panel due price/space/install work considerations?
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  #12  
Old 10-18-2019, 11:54 PM
Cumulo Cumulo is offline
 
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Location: KHMT
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My entry into this Inexpensive Temp Probe Derby is based on a thin film platinum device from, you guessed it, Digikey. Suprisingly, they are cheap, accurate, but also very tiny.

I thought some of you might be interested in another way to git'r done.

What I have now is basically a GTP 59 probe clone.

I bought a bunch of TE pn 223-1820's which are 1kohm units. To get the required 500 ohms for the GAD 13, I put 2 in parallel to make what is effectively a single 500 ohm device. One connection goes to GAD13 pin 6. The other side of the device goes to pin 3 AND 8 with a jumper.

If you are all about precision( i am), or have a long run or are using thin wire, consider using 3 wires. In this case, run 2 separate wires from one side of the device to pins 3 and 8 of the GAD 13 - no jumper. This is the way the GTP 59 is installed. It only makes a very small difference. Spruce's 24 gauge x 3 shielded cable or similar might be a good choice for probe cable.

Tested accuracy was pretty good. Distilled water ice temp was spot on 32F. Boiling water temp was ~207.9F. The calculated temp for my pressure altitude was 209.33F. So, off by ~1.5F, quite good. Less than 1 degree C. This will correspond to a small fraction of a degree at flight air temps. Testing was done using 2 short wires and jumper.
ron

Last edited by Cumulo : 10-19-2019 at 01:50 PM. Reason: expanded
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  #13  
Old 10-19-2019, 02:36 AM
tangocharlie123 tangocharlie123 is offline
 
Join Date: May 2017
Location: QLD Australia
Posts: 58
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Hi Cumulo

What did you mount the sensor in/ on and where did you locate it.
Cheers
Peter
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  #14  
Old 10-19-2019, 12:48 PM
Cumulo Cumulo is offline
 
Join Date: Apr 2015
Location: KHMT
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Hi Peter

The sensors I used have leads, so the mounting would be similar to using the AD590- .

The easiest mounting for most applications would be to solder the device to the cable wires and then install it in a small piece of tubing, maybe brass tubing as the OP described.

In my case, the sensor location will be a well ventilated wheel well and mounting will be by simply cable clamping in place.

BTW, The specs for these RTD devices are generally much better than the cheapo grade AD590 ($20). I bought 25 for of these RTD's for ~$40.

Also, this approach may be a satisfactory sub for the GTP 59 to use with the G3X. Someone should look into that, since, in that case, there is no alternate probe source for the GPT 59 $$$.

Ron
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  #15  
Old 10-19-2019, 03:21 PM
Adrian Bonwitt Adrian Bonwitt is offline
 
Join Date: Jun 2013
Location: Alton, Hampshire
Posts: 25
Default Density altitude..

I wonder if Garmin don't want density altitude to be displayed when airborne as it could then be confused with real altitude...which is a shame as knowing the density altitude can be really helpful at times...

This is a great thread as getting reliable OAT is important (particularly to avoid icing)...and the Garmin (albeit TSO solution) is expensive...
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  #16  
Old 11-01-2019, 07:03 PM
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D Weisgerber D Weisgerber is offline
 
Join Date: Sep 2019
Location: Ionia Michigan
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I just got my G5 to work with a GAD 13 and an EDMO 655 OAT probe. I went with the less expensive probe $89 from ACS. I had to install a CAN Terminator at each end. I'm very happy with these results.
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  #17  
Old 11-21-2019, 05:05 PM
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rolf rolf is offline
 
Join Date: Jan 2005
Location: Petaluma CA
Posts: 59
Default Digikey Temp Probes

Copied Cumolo's sensors from Digikey. Works Great!.
Don't forget to update the G5 to the latest firmware, or it may not recognize the GAD13
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