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Engine compartment temperature sensors

SteveHRV7

Member
I am trying to find a post(s) on sensor engine compartment temperature sensors. I must not be searching on the proper key words. It seems like there are some stick on "dots" that change color with various temperatures. They are used to sense (and record) temperatures in the engine compartment etc. Does anyone know what these are called and where you can get them? I have an exhaust pipe very close to the cowl and the mixture cable. The cable is firesleeved, the cowl has reflective material on it and the exhaust pipe is wrapped in that area - but I would like to know how hot the cowl and cable actually get.
Thanks!
 
Resurrecting....

I want to build an air temperature sensor that I can locate at various positions under the cowling, and connect to my G3X system for real time display and logging. G3X does support various types of aux temp sensors - I'm curious if anyone has built their own custom undercowl sensors and hooked them up to their EFIS. I'm looking to build something CHEAP by not using an aviation spec sensor / probe. Suggestions appreciated.
 
If you just want to log them and don't need them included in the EIFS, then you could always use an arduino with a thermocouple. Integrating it or having it display in an EFIS system sounds interesting but don't have that experience yet.
 
The alt engine guys are the people to talk to about this kind of thing. They spend a lot of time measuring the things you're talking about, because each cooling installation is different & they need data to know how well their installation is working.

You can roll your own thermocouple sensors by buying the wire in bulk (ebay) and spot welding the ends together. Or just buy Chinese thermocouples on ebay.

There are also solid state sensors that are pretty easy to use, if you can solder & run wires. Here's a short read that should get you started.

http://www.johnloomis.org/ece445/stamp/nv_mag/st_ap29.pdf

Obviously, the meter you use would be different for thermocouples vs various solid state sensors. The nice thing about the LM34 is that you can use a standard digital meter to, for all practical purposes, directly measure temps.

Charlie
 
Been using a pair of them on long leads for years. Just place them anywhere a temperature reading is desired. Be sure to block sources of radiant heat if air temperature only is desired.

(1) National Semiconductor temperature sensor, LM34AH.

http://www.ti.com/lit/ds/symlink/lm34.pdf

https://www.digikey.com/product-detail/en/texas-instruments/LM34AH/LM34AH-ND/5055993

(2) Three-conductor wire. 20 or 22 gauge is fine. Shielding not necessary, but the shield mesh can provide physical protection

(3) Self-adhesive (heat melt glue lined) heat shrink tubing, ?? and smaller

(4) Good digital voltmeter or voltage panel display

(5) Solder tools and supplies

(6) Fuse and connectors as required (current draw is very low)

The output is read with an ordinary hand-held digital multimeter or a digital voltage display. I don't know if they can be calibrated to the Garmin display. The voltage corresponds to temperature, 10mV = 1 degree F. Example: Meter says 2.5 volts. 2.5V is 2500mV. 2500/10 = 250F. Whatever the meter says, just move the decimal point two spaces to the right and you have temperature. (The same sensor is available in Kelvin if that helps.)

Only three connections, aircraft power, ground, and sense. Connecting to the avionics bus so the sensor is ?on? with flight instruments is fine. Meter negative and probe ground should both be connected to the aircraft single point ground bus.
 
I connected many temp sensors to my MGL IEFIS system. Cowl temp, ignition temps, oil cooler in/out temps. I use the LM335 sensors, they work pretty good. Only two wires needed. Just make sure you secure the wires to the sensor with some silicon to keep them from snapping off the sensor.
 
you can get thermocouples with 3 meter long leads and a battery powered digital display from China (ebay or aliexpress.com) for less than 10 bucks. Free shipping! Of course if the fact that the Chinese government offers free shipping on its products is a totally unfair trade practice (which it obviously is) which puts local mfgs at a massive disadvantage then don't buy it. :)
 
If you have an engine monitor, it may have an unused port for another temp probe. If so, that may be the easiest and may also offer data logging for it as well. This worked for me using Grand Rapids EIS 4000 engine monitor.

Bevan
 
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