In my apartment in the summer's almost 28 degrees. And I was not able to watch as my sweet little female rat "Lani" panting always sticks her head out of the house. She lives in my living room cabinet, three drawers, which I rear grille and front covered with a plexiglass window. And though really more than enough holes are present, I have donated her only once a ventilation system that blows easily into the back of the cage. It took but very little improvement, as I could see from the measured temperature. In the cage, it had to weddings still almost 28/29 degrees, just like in the apartment too.

Ok, I thought. How can something cool without the technical complexity of a real air conditioner? The solution is a component called the Peltier element. This is a small ceramic disk with two cables, which functions as an electric heat exchanger. Feeds it with direct current, so one side cold and the other hot. If you change the polarity of the wires change, then the sides. These elements work exactly like a refrigerator and used for example in the coolers for cars to use.

The starting point for my cooling system is a piece of plastic drain pipe, at the entrance I've attached a PC fan with mounting adhesive. The other end branches into two Aluschläuche that I can bend and rotate at will, so I can distribute the air in the cage. Then I cut this tube at the top in order to use the Peltier element. The item must be equipped with thermal paste on both sides and two heat sinks. Especially the hot side must necessarily be operated with large fins and a powerful CPU fan, otherwise the item be damaged! The black heat sink on my photos, for example, is too small, so I verbrutzelt the first element, too. In the meantime there tinkers a cooler for an Intel i5. For the temperatures between the two sides to shield well I have a piece of a Silicone baking sheet cut out as a base plate, in the middle with a recess for the Peltier element. Then both sides of the heatsink with thermal grease screwed, in addition to the hot side with a fan. Then, this base plate with the cold heat sink down into the opening is stuck in the drain pipe. There, then the cold heat sink is bepustet by the fan at the entrance of the tube, so that only the cold air is blown through the tubes into the cage. Is on the hot side hot soz the exhaust air blown into the room.

Both fans I together with the Peltier element connected in parallel to an old notebook 12V power supply with 10A, since the element performance has correctly and well and happy 6 to 9A pulls. With so much power so a temperature control is essential! We do not want, after all, frozen Lani . Such controls are quite cheap in kit form, in stores or at eGay from Hong Kong. When exceeding a preset temperature, we just closed a relay and if it falls below this temperature re-opened. In this relay, I then plugged my power supply.

Optionally, it can be in certain conditions also a good idea to run our cooling with less than 12V, as depending on the power of the Peltier element can be less sometimes more. For example, if for reasons of space, the heat sink must not be too large, you should reduce the power to prevent overheating and to prevent damage. For this purpose, a circuit is called pulse-width modulator, the other hacks than a banal series resistor, the voltage in small pieces (ie pulses). Thus the heat loss is reduced along with power consumption and increased efficiency. Here, secondly you will find a simple circuit for such a PWM http://www.atx-netzteil.de/pwm_mit_ne555.htm

My air conditioner has passed the test in any case fully Lani. She even loves to sit directly in front of the hose out and hold their snout in the chilly wind.