Moderators: richierich, ua900, PanAm_DC10, hOMSaR

 
Catrik
Topic Author
Posts: 3
Joined: Tue Jun 28, 2016 8:14 pm

Vintage EGT gauge, what probe?

Tue Jun 28, 2016 8:32 pm

Hi,

I thought you guys might know. For example this gauge http://m.ebay.com/itm/190867941600?sojT ... mwBanner=1

What kind of temperature probe/sensor do I need to hook it up? It would be going in to a car.

What about gauges that have round, multi pin connectors, like these http://m.ebay.com/itm/Commercial-Jet-En ... nav=SEARCH
How do they operate? Are they standardized? Could I just input 0-5v from a normal car sensor to make it work or what mods would be needed? Other than to just use the shell and put car gauge internals.

I would really appreciate any help, I have been thinking about this for a long time but haven't found any info on how to hook up plane gauges. There is just nothing as appealing in car aftermarket gauges compared to these vintage plane gauges are!
 
User avatar
Jetlagged
Posts: 2564
Joined: Sun Jan 23, 2005 3:00 pm

Re: Vintage EGT gauge, what probe?

Wed Jun 29, 2016 6:46 pm

Usually the sensor is a thermocouple. The hot junction is in the engine and the cold junction is in the indicator. It shouldn't be too hard to connect to a 5 v DC input. You would need to ensure the input current was in the milliamps range, which you can achieve with appropriate resistor values. The C-A on the backplate refers to chromel-alumel.

The indicators with the bayonet connector are probably also thermocouple driven. Most of those pins probably aren't connected to anything, it's a standard connector. There might only be the thermocouple input and AC lighting.
The glass isn't half empty, or half full, it's twice as big as it needs to be.
 
Dalmd88
Posts: 3138
Joined: Fri Jul 28, 2000 3:19 am

Re: Vintage EGT gauge, what probe?

Wed Jun 29, 2016 8:21 pm

Unless your car runs extremely hot you will not see much movement on the gauge. Maybe up to 100 C.
 
Catrik
Topic Author
Posts: 3
Joined: Tue Jun 28, 2016 8:14 pm

Re: Vintage EGT gauge, what probe?

Thu Jun 30, 2016 1:28 pm

Dalmd88 wrote:
Unless your car runs extremely hot you will not see much movement on the gauge. Maybe up to 100 C.

Huh? That is an EGT, exhaust gas temperature gauge, not coolant/oil gauge if that's what you meant. 750C is the max recommended sustained EGT on a 6.2 diesel so the gauge is spot on :)

Jetlagged wrote:
Usually the sensor is a thermocouple. The hot junction is in the engine and the cold junction is in the indicator. It shouldn't be too hard to connect to a 5 v DC input. You would need to ensure the input current was in the milliamps range, which you can achieve with appropriate resistor values. The C-A on the backplate refers to chromel-alumel.

The indicators with the bayonet connector are probably also thermocouple driven. Most of those pins probably aren't connected to anything, it's a standard connector. There might only be the thermocouple input and AC lighting.

Thanks! Went to see what Wikipedia says about thermocouples and chromel-alumel actually is Type K, which is the most common (only?) probe used in automotive EGT use. https://en.wikipedia.org/wiki/Thermocouple#Type_K

So the probe has the hot junction and the gauge has the cold junction. Temperature difference between the two will cause electric potential difference which is translated to temperature. Do you know what the "use 8 ohm c-a leads" refers to, is it part of the hot junction (probe) or does it refer to the wires between the junctions?

Here is about the AS413 standard http://standards.sae.org/as413/
 
User avatar
Jetlagged
Posts: 2564
Joined: Sun Jan 23, 2005 3:00 pm

Re: Vintage EGT gauge, what probe?

Fri Jul 01, 2016 3:44 pm

Thermocouple leads are sold according to resistance so if you get 8 ohm leads for type K it should work OK. Whether this means the total loop resistance is 8 ohms or it's 8 ohms in each wire I don't know.
The glass isn't half empty, or half full, it's twice as big as it needs to be.
 
Okie
Posts: 4146
Joined: Wed Jul 16, 2003 11:30 am

Re: Vintage EGT gauge, what probe?

Fri Jul 01, 2016 7:55 pm

It does not get much easier than this.
Good reference for thermocouple EGT and CHT

http://www.rst-engr.com/rst/articles/egtcht.pdf

Okie
 
Dalmd88
Posts: 3138
Joined: Fri Jul 28, 2000 3:19 am

Re: Vintage EGT gauge, what probe?

Fri Jul 01, 2016 10:28 pm

Catrik wrote:
Dalmd88 wrote:
Unless your car runs extremely hot you will not see much movement on the gauge. Maybe up to 100 C.

Huh? That is an EGT, exhaust gas temperature gauge, not coolant/oil gauge if that's what you meant. 750C is the max recommended sustained EGT on a 6.2 diesel so the gauge is spot on.
/

I was thinking coolant gauge. Never really thought about what the EGT was on my car.
 
Catrik
Topic Author
Posts: 3
Joined: Tue Jun 28, 2016 8:14 pm

Re: Vintage EGT gauge, what probe?

Fri Jul 08, 2016 9:34 am

Okie wrote:
It does not get much easier than this.
Good reference for thermocouple EGT and CHT

http://www.rst-engr.com/rst/articles/egtcht.pdf

Okie

Thank you!! Im pretty confident I can get it to work now. Found new old stock of the gauges for 25€ on ebay, I should have it soon.

Who is online

Users browsing this forum: mrpippy, Starlionblue and 16 guests

Popular Searches On Airliners.net

Top Photos of Last:   24 Hours  •  48 Hours  •  7 Days  •  30 Days  •  180 Days  •  365 Days  •  All Time

Military Aircraft Every type from fighters to helicopters from air forces around the globe

Classic Airliners Props and jets from the good old days

Flight Decks Views from inside the cockpit

Aircraft Cabins Passenger cabin shots showing seat arrangements as well as cargo aircraft interior

Cargo Aircraft Pictures of great freighter aircraft

Government Aircraft Aircraft flying government officials

Helicopters Our large helicopter section. Both military and civil versions

Blimps / Airships Everything from the Goodyear blimp to the Zeppelin

Night Photos Beautiful shots taken while the sun is below the horizon

Accidents Accident, incident and crash related photos

Air to Air Photos taken by airborne photographers of airborne aircraft

Special Paint Schemes Aircraft painted in beautiful and original liveries

Airport Overviews Airport overviews from the air or ground

Tails and Winglets Tail and Winglet closeups with beautiful airline logos