Refrigerator against

    The experiment was completed for
    20 hours with periodic bullying - the flight is normal.



    Task

    Since Virtualrilka is used in vehicles and in some street devices, it was necessary to check how it works at low temperatures, otherwise winter is on the nose. In theory, if there is no condensation, then it should hold out for some time with minus. But up to what subzero temperature the operability will remain and what will happen with the condensate is unknown, it is necessary to check. Moreover, to check naked - the piece of iron should be placed in a cold room as is, without any closed box, because the percent is heated (and the Wi-Fi chip too), as a result, the box will be heated from the inside by the forces of Virtualka itself.

    Where to get the minus temperature in domestic conditions (outside the window there is still a positive autumn)? Of course, in the refrigerator :-) More precisely, in the freezer. Judging by the stars drawn on the refrigerator door and according to the description on Wikipedia, this signature "* (***)" indicates the potential possibility of a freezer to arrange frost of 18 degrees or more.

    At the same time I will get an answer to the question that has long been sitting in my head - will wi-fi work from a closed metal refrigerator.

    What happened

    The virtualrilka was placed in an open box, more precisely, from the box there is only a base and walls. This is so that the piece of iron on the metal bottom of the freezer does not lie. Although the bottom is tinted, but still somehow I do not want to just put it like that.

    Our usual camera is connected to the Virtualrilka. Video from the camera is sent to the YATV server, from where it can be viewed with their player, built-in to a specially made page.

    Communication - through Wi-Fi, through our module based on Marvell W8686.

    Power is supplied from the outside, from a 5V power supply.

    Also, the well-known DS18B20 thermometer is connected to the Virtualrilka, which is interrogated once a second and the received temperature information is sent to the server. A client script on a web page loads information from a thermometer every second and displays it in a browser. Everything seems to be simple.

    Two links were made for the feedback, clicking on which lights up or extinguishes the LED on board the virtualka.

    The focus of the camera is fixed, the focal length is greater than the distance at which the camera is located from the piece of iron, so the video is not quite in focus, but the main components seem to be visible.



    You can see if Virtualrilka is still alive in the refrigerator here http://video.virt2real.ru/show/subzero/

    Preliminary results

    I put a piece of iron in the refrigerator at about one in the morning. At the beginning, the temperature kept about -6 degrees, I already started to think that the percent and wifi are so warm that they heat the entire compartment of the freezer. But soon the temperature cheerfully crawled down - the compressor turned on. I forgot that it does not constantly work. The minimum recorded temperature is minus 19.64 degrees. After turning off the compressor, the temperature rises to about 11-12 degrees of frost. Then, after some time, it goes down again and so on in the cycle.



    Wi-Fi works fine. Pah-pah-pah, the signal level inside the refrigerator is no worse than the outside.

    Total, now (half past five in the morning) the piece of iron is in the refrigerator for more than four hours, the flight is normal. Testing will be until Sunday evening, you never know, maybe a piece of iron, or a camera, or something else will die. The main thing is that the compressor of the refrigerator does not die, otherwise the wife will kill for such experiments.

    Of course, this is not such an outstanding experiment than in the case of dispersing Arduino under liquid nitrogen (BarsMonstru Respect), but for practical purposes it’s quite good for itself.

    UPD> If anyone suggests complicating the experiment, feel free to comment. If someone wants to offer something, but cannot write on Habr - write comments here .

    forum.virt2real
    wiki.virt2real

    UPD> Here they prompt that Raspberries have already been frozen. Thanks for the reference, have not seen before. habrahabr.ru/post/178647

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