Recently I noticed that a skinny and very shy cat, with eternally sad eyes, settled in the barn attic ...
He did not make contact, but he watched us from a distance. I decided to treat him with a premium class feeding, which our domestic cat-faces gobble up. Even after two months of treats, the cat still avoided all attempts to contact him. Perhaps he got it from people earlier, which led to such fearfulness.
As they say, since Mohammed does not go to the mountain, the mountain itself will come to Mohammed. In connection with the upcoming change of season and the inevitable cold snap, I decided to bungle him some kind of “house”, with the placement of it on his territory there, that is, in the attic.
The basis of the house is a couch from a double box from Hainan mangoes. Doubled, this is when the box is inserted into an inverted lid from it. Each of the halves is double, so the box turned out to be a quadruple, with increased strength. The Chinese know a lot about boxes, as the size was perfect for cats. 🙂 Between the layers, I put a lining from the laminate in the box for additional thermal insulation. Then he put 2 layers of centimeter foam rubber on the bottom, and on top - an old, terry towel folded three times.
Knowing what a “milk step” with the release of claws is, and how any bedding will surely crumple over time, I sewed all three layers of the towel through to the box. Moreover, it was not sewn with threads, which can easily turn out to be gnawed or torn by claws, but with copper (winding) wire in varnish insulation, as much as 1,2 mm thick. Yes, harsh, but for that it is anti-vandal, from cat claws or teeth.
I also stitched all the corners with a similar method so that the litter could withstand its laying shape, even despite any bullying from the settler.
But it’s not enough just to put a soft couch, because frosty drafts walk in the attic in winter, with the same temperature as on the street. So, there was a task to create around the crib, something like a “dome”, to keep the heat emanating from the cat. For this, the prepared bed was placed inside a larger box.
On the side wall of the outer box, I cut a semblance of a “door” that self-covers the passage so that the heat does not escape much.
As the work progressed, domestic cat-faces several times managed to try on such a soft and cozy home for themselves:
They terribly liked to gently stomp in the couch, from which within 5 minutes everyone was immediately flattened into a dream:
Well, since we will keep the temperature around the tenant by means of an externally closed perimeter, then why not generate heat right there so that the tenant cat can save heat loss in his body. To do this, two more layers of thick cardboard with thermal insulation were placed at the bottom of a large box, between the layers of which two active, thermal heating elements from a multi-core, constantan cable were laid. They were designed for power supply from USB, that is, 5 volts. Having connected them in series, I redid it for power supply from 9 - 10 volts, with a current consumption of about 1 Ampere, which would give us a heater power of 9-10 watts. And this is already a lot, for such a small heating volume.
Since the animal is a priori illiterate, it can theoretically gnaw through the power cable for the heating pad in the box. And if so, then you should think about the issue of ensuring the guaranteed safety of the health of the animal, from a possible electric shock. To ensure such a task, I abandoned the use of modern impulse blocks and chose the old-mode type of transformer power supply, with galvanic isolation from the network (it was not included in the pictures). Although the impulses also have a decoupling, they still “pinch” pretty much, for example, with respect to the heating circuit.
Well, since we went to the “bells and whistles” house, I thought that I would install the box in the attic, nail the pediment back with sheathing and goodbye. And what if you make some kind of video control? It will be interesting to know if the cat will take advantage of the whole idea at all? I did not want to pull the video cable, the footage would be rather big, and therefore I decided to resort to transmitting video over the air. Once I got a burned-out 5,8 GHz video transmitter, the owner of which somehow managed to burn it. In particular, the output stage of the RF power amplifier turned out to be burned out. Having removed the faulty microcircuit of the output stage, as well as the entire SMD “piping” surrounding it, I connected the output of the video transmitter buildup stage with a coaxial “bypass” to the output SMA connector for the antenna. Using the Arinst 23-6200 MHz vector reflectometer, I measured the reflection coefficient S11 and made sure that the output impedance at operating frequencies remained within the acceptable range, around 50 ohms.
Curiosity crept in, but what then is the real power of such a "castrated" video transmitter, if you feed the antenna directly from the "buildup", that is, without a power amplifier at all? Measured using an Anritsu MA24106A precision microwave power meter, in a suitable range up to 6 GHz. The real power on the lowest frequency channel of this transmitter, 5740 MHz, was only 18 milliwatts (out of 600 mW). That is, only 3% of the former power, which is very small, but nevertheless acceptable.
Since it so happened that the available microwave power is not enough, then for the normal transmission of the video stream, you will have to use a better antenna.
I found an old antenna for this 5,8 GHz band. I came across an antenna of the “helical gear” or “clover” type, that is, an antenna with a spatially circular polarization vector, in particular, the left direction of rotation. In the conditions of urban development, it is even good that not a linear polarization of the signal, but a circular polarization will be emitted. This will make it easier and better to deal with the inevitable reception interference caused by reflections from nearby obstacles and buildings. In the very first picture, in the lower right corner, it is schematically shown what the circular polarization of the propagation of the electromagnetic radio wave vector looks like.
On a freshly calibrated vector network analyzer (VNA device), having measured the VSWR and impedance of this antenna, I experienced some discouragement, since they turned out to be very mediocre. Having opened the covers of the antenna and having worked with the spatial arrangement of all 4 vibrators available there, with an indispensable condition for taking into account the permeability of the plastic of the covers-lids, it was possible to completely remove the parasitic reactivity of both capacitive and inductive nature. At the same time, it was possible to drive the active resistance to the central point of the circular Volpert-Smith diagram (exactly 50 ohms), at the selected frequency of the lower channel of the existing transmitter, namely at the frequency of the planned broadcast of 5740 MHz:
Accordingly, the level of reflected losses (on the average plot of the logarithmic magnitude) showed a microscopic value of minus 51 dB. Well, since there are practically no losses at the resonance frequency of this antenna, then the voltage standing wave ratio (VSWR) shows perfect matching within 1,00 - 1,01 (lower SWR graph), at the same selected frequency of 5740 MHz (lower available transmitter channels).
Thus, all the available small power can be radiated into the radio without loss, which is what was required in this case.
Gradually, here is a set of additional accessories that I assembled for installation in a cat house:
Here, in addition to the “warmers” (large and shiny plates at the bottom), a remote on / off system was also added, in the form of a radio remote control and a receiving-relay unit, configured for mutual radio communication in the 315 MHz band.
This is necessary in order not to constantly affect the sleeping cat with LED lighting and the included radio transmitter, even if it is extremely weak and placed behind the metal sheathing of the attic pediment.
The animal should sleep at rest, without artificial lighting, a glaring video camera nearby and harmful radio emission penetrating the living cells of the body. But for a short time, at any time upon request, you can power the entire video setup with diode strips-lamps from the remote control, quickly look at how cat facies are there, and immediately turn off the system.
In terms of electricity consumption, this is also the optimal and economical choice.
I cut the LED strip of 12 diodes into two parts, glued it and “sewn” it on top with the same harsh copper wire so that it would not break from a possible claw attack, and shone where it was needed:
A video camera with a video transmitter and a pair of LED strips powered for savings through a pair of current-limiting resistors (390 ohms each), as well as a radio switch receiver, consume only 199 mA, when turned on, from a second 12 volt current source . In the off state, in the standby mode, there is only a radio switch, with a standby consumption of only 7,5 mA, which is very small and, in fact, is masked against the background of loss of consumption metering from the network.
Electric heaters are also not manually turned on. For them, a step-down transformer is connected through a radio-controlled thermostat, the remote control with sensors of which is located in the house. So when it's already warm, the heating system will automatically turn off, and connect only with a drop in outside temperature.
The video camera was selected even from open-frame ones, but with a rather high light sensitivity of 0,0008 lux.
From an aerosol, I covered it with polyurethane varnish, for atmospheric protection and changes in humidity, or even possible precipitation.
Sheathed antenna and camera after varnishing, rear view. Below you can see the red tape that has not yet been removed, covering the contacts of the main connector:
I had to rebuild the lens focus on the video camera to work in the near zone, at the main distance of 15-30 cm.
The assembled part of the equipment (with wiring) on the house-box, before sending the whole structure to the attic:
As you can see, here the “ceiling” of the box is reinforced from the inside and is also “stitched” with copper, in case the cat decides to jump on top and trample on the “roof” of the house. For any adhesive tape there will be little, even if it is anti-vandal-reinforced.
Final tests on domestic cats, with lights on and video transmission on, showed acceptable success for the conceived concept:
1) With Siamese:
2) With tricolor:
The video link, of course, is not Full HD resolution, but the usual analog SD (640x480), but more than enough for a short control. There is no task to consider every hair, it is important to understand whether the object of observation is alive at all.
The day came for the entire structure to be erected at the accommodation facility, which was the old attic in a small shed with a local stoker. The attic turned out to be unattended, it was just boarded up with nails and that's it. I had to rip out about 50 nails with tongs, located along the perimeter of each of the two sheets of pediment sheathing.
I expected the cat to be shy and immediately run away from the noise of such "instrumental surgery" with the attic. But it was not there! He lunged at me, snarling frantically, hissing as he tried to inflict clawed injuries. Apparently, he had previously fought with local cats more than once and won this shelter for himself in battles. This is unknown.
For the first time I saw such a lair of an attic cat. This is a very dusty, old glass wool, flattened to a flat state. It looks like the first cat lives there. Nearby lay a pile of bird feathers, apparently the remains of eaten prey. Around a cluster of old and black cobwebs, a mass of dust, feathers and skeletons of small birds, in general, an unsightly and terrible sight:
Stably placing the “cat house” under the roof and connecting the wiring, he tightened the old skin with new screws.
The video transmitter was immediately planned for removal from the metallized "shading" zone, so that nothing would prevent the already very weak radio wave from flowing around the yard, and reflected from the fence, penetrate through the window opening into the house, to the receiver with the monitor. Previously, the transmitter was wrapped in heat shrink with sealed ends and mounted on a mast leg so that there were no conductive structural elements around the antenna at a distance of 1,5 - 2 Lambda. The photo shows a curved antenna, saying that it is so sloppy? .. It’s not a matter of “accuracy”, but in a carefully calibrated angle of spatial orientation of the antenna, taking into account its radiation pattern. A little later, I had to open the pediment again, as well as fix the transmitter in a different way and bend the antenna with an optimal angle, including also to protect against falling rain and hail with the wind, which always fall strictly from the same direction. Taking into account two factors at once, the coaxial feeder was bent, but it makes no sense to duplicate a similar photo.
An inquisitive reader may notice, they say, why did you have to open the attic again? Because after waiting for three days and periodically turning on the video control system, I never found a cat in a new house. Perhaps he is simply afraid to approach, or look inside. Perhaps he smelled other people's cats from the box. And most likely the cat did not even understand that this is a house with a stove bench and you can climb in there by simply sliding the cover of the slot with your forehead. The reason is unknown.
I decided to lure him through the smell of sweets. Well, at least for acquaintance, let him understand that there is no danger in the box, and that it is really high there. I would sleep myself, but I need to work. 🙂
In general, having re-opened access to the attic, in front of the entrance to the box and to the corridor of the box itself, as well as to the couch, I threw some feed pellets with a fresh smell.
Hooray, the idea with a tasty trick worked!
After half an hour, the desired object was extremely cautious and in small steps, but found the entrance to the house, visited it in full (and more than once), having eaten all the goodies there.
(the photo is now a different monitor, with built-in radios and with green inscriptions)
Thus, the attic cat got an equipped “house” with a Hi-Tech bias, and I have a plus sign in karma for a good deed, and, in addition, the possibility of externally controlled video monitoring, what is there and how. It would be possible to capture the received video stream and organize its broadcast to the network. It would be a webcam.
But since there is nothing fundamentally interesting here, and secondly, there is no need to disturb the cat, then there is no organization of capture with broadcast.
But there were no mice, and this is definitely the merit of one of ours, and this cat.
Our territory and our neighbors have been cleared to the fullest.
So kotofaciy deserved a clean, warm and quiet bed for rest.
May he live there as long as possible, in comfort and peace.
Good luck to the shy Devil with sad eyes:
Source: habr.com