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Author Topic: Practical experience operating Consumer ICs outdoors  (Read 1293 times)
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Calgary, AB
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I am in the initial stages of investigating an outdoor project that would expose the electronic components to less than -30˚C during winter operation.  During the summer it would be disconnected, so the high end temperature is not a concern.   

Project is to build a solar pond heater to keep the fish pond from freezing over during the winter (it is a shallow pond and deepening is not really an option for the size of my pond).  If it works this winter then I will add additional features for auto-logging performance remotely with an Arduino (and wireless) to provide more granular control.

First step in my project is to monitor: air, solar panel and water temperatures.  Based on conditions, simple logic will determine whether to pump water to the solar panel, or assist with a heater, or night time heating required.   

Was planning to use Consumer Grade electronics due to easy availability which generically only should operate as low as 0˚C. 


Question to the group is: “What is your practical experience when placing electronic projects outdoors in cold temperatures?”  I have never built anything to operate outdoors during the winter.

My thoughts so far:

1) Just source Military grade components and forget about it?

2)  Space is not a concern , I can build a larger enclosure with insulation to retain any heat generated by the electronics which should not be much (op amp, comparator, and some 74xxs, power transistor), the pump motor will only be driven electronically during daylight hours, so I cannot plan on constant heat from the transistor..

3) Adding another LM335 transducer to monitor internal temperature of enclosure to start a heater if required.   Considering the energy required to heat the enclosure, the purchase of higher grade components becomes justified for the test period.  However, for adding something like the Xbee transmitter, planning for heating up front maybe beneficial long term.

4) If I go with heater, what have you used for a heater?

Thanks for your suggestions or experiences.
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If I go with heater, what have you used for a heater?

Just use power resistors sized for the amount of heat required. Turn them on and off via a switching transistor wire to the arduino with a temp sensor. Or pwm it with a PID control function and have continuous heater control. Resistors are 100% efficient at converting electrical power to heat output.  smiley-wink
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If I go with heater, what have you used for a heater?

Just use power resistors sized for the amount of heat required. Turn them on and off via a switching transistor wire to the arduino with a temp sensor. Or pwm it with a PID control function and have continuous heater control. Resistors are 100% efficient at converting electrical power to heat output.  smiley-wink

Good sugestion, available power power is not limited, as I have ruled out using batteries, too cold and power requirements to be met,  the pump  will require 12V 2A and heater 120Vac.

I also considered good old fashioned light bulbs, that generate heat.  They say to heat a doghouse in Calgary with a incadescent 100W light bulb, to keep the dog warm, not sure how low of a temperature that would be effective. 

Regards  Bill
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Couple things come to mind:
If it gets cold the solar panel may freeze overnight, that'd be an issue.

I would use some form of heater, my Arduino didn't appreciate below freezing temps much.  I've been contemplating doing some more testing with my freezer just for giggles.

Heat wise there's no reason the Arduino couldn't control a resistive heating setup to keep itself warm, should be fairly simple to write/wire.
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No need to go military - many ICs and discretes come in an Industrial temperature grade that is typically qualified* over the range -40 ~ +80C, for not much more cost than commercial grade parts. At low temperature, condensation will likely be your biggest worry. If you can, hermetically seal the main electronics box ("otter box" might work) with a silica gel packet inside just in case.

*This means only that they are not tested/guaranteed to lower temps, not that they will stop working (and it may be the limit of the manufacturer's thermal test chamber, not the part). Personally, I've yet to see an IC fail outright at LOW temperatures, although more 'analog' stuff can and will drift (caps, resistors, crystals, etc. will change in value; timing-sensitive things like RS232 may be out of whack and your sensors may need temperature-specific calibration outside the guaranteed range). One project I did at work (PIC-based wireless sensor network for a railroad application) had to be qualified to -50C. I figured "what the hell" and set the test chamber to minimum (turned out to be -67C) and let it run with some prototypes over a long weekend. I was not able to induce any 'hard' failures, but I did find that the radios outside the chamber would lose sync with the radios inside once they were about 50C apart - guessing the crystal frequencies had drifted apart enough that they were not talking on the same frequency / timeslots anymore. Once the chamber warmed up a bit they would start communicating normally again!
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I also considered good old fashioned light bulbs, that generate heat.  They say to heat a doghouse in Calgary with a incadescent 100W light bulb, to keep the dog warm, not sure how low of a temperature that would be effective.

That is a good idea...

To keep warm the project box, the use a Heat lamp control by a LM335 <-- inside temp monitor and of course insulation <-- The "pink" stuff, and make sure the inclosure is seal. ( lots of wet snows/freezing rains/rains/snow )

Just an idea...  
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As others have said, condensation will be the biggest problem.
You need to keep all the electrical bits above the dew point.

Use the Arduino to measure the temperature and control a heater, or buy an off the shelf thing like this http://www.awrtech.co.uk/dew.htm



« Last Edit: August 18, 2011, 05:47:25 am by mjbmikeb » Logged

Calgary, AB
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Thanks for the replies so far:

Lefty  - for the resistor suggestion

Bobnova – solar panel(s) are self draining (pumping the pond water through it so antifreeze not an option if I want the fish to survive), and water pump will be turned off before internal panel temperature reaches freezing.

Drmn4ea – your experiences are illuminating, and I had not considered condensation.  The fact I am considering future wireless control, from your experience keeping the module warm will be a consideration.

Techone  - I know the pink stuff very well, used many sheets on my train layout for scenery the new purple has better R factor,  as for rain, Calgary is almost a desert re: rainfall, and the snow is dry ;^)  

« Last Edit: August 17, 2011, 11:06:59 pm by Bill_Kerr » Logged

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I know the pink stuff very well, used many sheets on my train layout for scenery the new purple has better R factor,  as for rain, Calgary is almost a desert re: rainfall, and the snow is dry ;^)

I did not know about the purple stuff ( I better check it out at Ronna or Home Depot )
I did know about Calgary being a desert, in Toronto, is humid and a lot of wet snows.

What about the electronics "boxs"  ( ABS, cruse control, engine control , ect ) inside your car ( specially made for Canada ), maybe a similar construction technique will be usefull for your project.

Just a taught...
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The ATMega328P is rated over a pretty broad range. How cold are you likely to see?

Temperature Range:
 -40°C to 85°C

-40C = -40F, that's pretty cold!
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-40C = -40F, that's pretty cold!

However -40C is still a pretty toasty +419.67 degrees on the rankine scale.

Lefty
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Just don't tell the chickens how warm it is smiley-cool
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The ATMega328P is rated over a pretty broad range. How cold are you likely to see?

Temperature Range:
 -40°C to 85°C

-40C = -40F, that's pretty cold!

Hi Crossroads

-30C for several days or more is not uncommon in the Calgary area.  Thats base temperature, wind chill can take it considerably lower.  Like to be believe it is a dry cold so not as chilling as a damp Toronto or Boston cold.

I am orignally from Toronto, and have visited Boston often for work and my hobby.  Too bad about Edaville a two foot railroad park, about an hour south of Boston did not survive.   People would know the area as Ocean Spray, the cranberry people.

The good news, is for my project, when it is getting that cold, I will be firing up the electronics to keep the 120V pond heater running at 100%, so I will be receiving some secondary heat from the heater circuitry to keep the enclosure warm.

Regards  Bill
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MCUs don't care about windchil thankfully, they aren't well enough hydrated smiley-grin

Me on the other hand...
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