Applications targeting to work between -70C to room temperature?

Hi all, I am looking for some low-temperature electronics systems applications. Would anyone give me some examples that circuits need to operate at low temperature (for example, -70C) to room temperature? It is better than the circuits are not required to operate at a higher temperature than room temp.

For instance, do some avionics circuit blocks need to operate at low temperature when the airplanes are in the air, but not necessarily need to work on the ground?

Thank you!

If it works at -70C it will work at room temperature.
Even high altitude aircraft have to land sometimes !

Even -40C is pretty damned cold, but not uncommon at high latitudes.

I have not done very much formal cold testing, but have experienced some definite problems to solve with crystal oscillators not always starting up, and problems with electrolytics at low temperatures.

bhl3302 said:

For instance, do some avionics circuit blocks need to operate at low temperature when the airplanes are in the air, but not necessarily need to work on the ground?

Thank you!

Click to expand...

System which monitors oxygen level, and which drops the masks in an emergency.

Systems which monitor flap position, gear position, etc.

Carburetors and pitot tubes are known to ice up. If there are systems which monitor these, then include them too.

If I were setting safety standards, I think I would have these vital aviation systems checked at low temps, and inflight, which are the times when they need to work.

Hi Warpspeed, it seems like crystal oscillators and electrolytics are the directre components to be used in these applications, but not the elctronic circuits/systems.

If I am looking for an electronics systems to be operate in this application, do you know what they can be? I am more interested in the systems which will be much more useful at high latitudes, but not so demanded in room temperature.

Thank you!

Warpspeed said:

If it works at -70C it will work at room temperature.
Even high altitude aircraft have to land sometimes !

Even -40C is pretty damned cold, but not uncommon at high latitudes.

I have not done very much formal cold testing, but have experienced some definite problems to solve with crystal oscillators not always starting up, and problems with electrolytics at low temperatures.

Click to expand...

Some military man pack sets work from -50 to +50 *C
Frank

Thank you BradtheRad! I need to do some homework to fully understand the items you pointed out. Would you give me some further guidance based on your inputs?
(1) Are they all electronics systems? Or some of them are just mechanical systems? If I have a circuit block, say, a voltage reference circuit, which can only work between -70C to 20C. Which items you mentioned can include this circuit block?
(2) In a different senario, is it possible to find some applications, either in the aircrafts, or in any other cases, that the operation above 20C is not needed? In another word, if I have a voltage reference circuit, which can only work between -70C to 20C, is it possible to find an application for it?

Thank you!

BradtheRad said:

System which monitors oxygen level, and which drops the masks in an emergency.

Systems which monitor flap position, gear position, etc.

Carburetors and pitot tubes are known to ice up. If there are systems which monitor these, then include them too.

If I were setting safety standards, I think I would have these vital aviation systems checked at low temps, and inflight, which are the times when they need to work.

Click to expand...

if I have a voltage reference circuit, which can only work between -70C to 20C, is it possible to find an application for it?

Click to expand...

Probably not.

If you live in most places, room temperature rises well above 20C sometimes.
How then can you test or repair it ?
Its just not a practical idea.

Sell the idea to the people on Mars, it's the type of thing they can probably use there.

Military parts are typically specified to operate between -55°C to +125°C.
I don't know of any devices, other than special purpose ones, that are specified outside that range.

In general though MOSFET and CMOS parts work better at cold so many of them may work below -55°C without a problem.

Its also not that difficult to insulate (whatever it is) and apply some heat via a resistive heater.
Some things such as batteries, are going to be extremely unhappy at -70C.

bhl3302 said:

Thank you BradtheRad! I need to do some homework to fully understand the items you pointed out. Would you give me some further guidance based on your inputs?
(1) Are they all electronics systems? Or some of them are just mechanical systems? If I have a circuit block, say, a voltage reference circuit, which can only work between -70C to 20C. Which items you mentioned can include this circuit block?
(2) In a different senario, is it possible to find some applications, either in the aircrafts, or in any other cases, that the operation above 20C is not needed? In another word, if I have a voltage reference circuit, which can only work between -70C to 20C, is it possible to find an application for it?

Thank you!

Click to expand...

Sorry, I only know a few generalities about aircraft circuitry.

Here are more environments requiring cold weather operation:

Snow avalanche monitor

Light beacons on mountaintops

Arctic radio equipment

Arctic wildlife radio tracking.

Arctic video and photography.

Infrared imagers for spacecraft and interceptors tend
to be operated about 80K (that's about -190C) and
incorporate a Si readout IC bumped to a II-VI detector
array. Obviously the ROIC had better work everywhere
between room temp (wafer probe) to at / below liquid
nitrogen (77K). This tends to require specially pulled
models and sometimes exclusion of unsuitable devices
(for example, BJTs kind of svck at cryo).

In such a circuit you would optimize a voltage reference
for flatness between -77K and 25C, and take what you
can get at higher temps where nobody cares.

Now, this is a prime example of a market that no sane
person would enter, it's pretty sewn up by a few big
players and infested with mad scientists at the federal
funding trough. But an example of technology, it is.