No doubt the drawer for vegetables - good and necessary in a city apartment device. Write about it with skill, as he is already two years in a row store vegetables on the balcony in the thermostat. The results are excellent: all that lay in the container in the fall, stored until the spring.
The container I made in the form of the box size HH three-millimeter mm plywood and wooden racks - bars-section 30x30 mm. Outside the box is insulated sheets of foam rubber of a thickness of 30 mm (bottom left without insulation).
Inside at the base with a height of 100 mm (from boards attached to the side walls) laid down planks section 147x10 mm. Hole Ø 15 mm boards I like and desyatikilometrovy the gaps between them for air circulation.
As a heater used two series-connected insulated spiral from the electric iron. Put them on the bottom of the frame, welded channel section and based on angles, bolted to the insulating textolite plate.
To improve air circulation attached to the rear wall of the sheet metal duct, starting at 30 mm from the bottom and ending at 10 mm from the lid. It was installed the sensor of the thermostat.
Container lid is down too from plywood and wooden bars. Only not insulated foam, and a foam thickness of 30 mm. Hinged part is connected with the fixed part of the lid with vents loops.
The entire container is covered on the outside with plastic wrap to protect from rain and snow.
Fig. 1. The size of the box
Fig. 2. The design of the container (the front wall of the box with insulation conventionally not shown): 1 - bottom, 2 - spiral heater, 3 - heater, 4 - corner, 5 - textolite fee, 6 - side walls of the box 7 - wooden stand, 8 - sheets of foam, 9 - thermistor, 10 back wall, 11 - foam, 12 - duct, 13 - walls cover, 14 - loop, 15 - stick, 16 - hinged side of the lid, 17 - hole Ø 15 mm, 18 - flooring Board, 19 - support beam
Fig. 3. Schematic diagram of the thermostat
Initially feared that the potatoes will freeze near the walls of the box, and the boards, on the contrary, to grow from excessive heat. However, nothing like does not occur, the temperature throughout the volume of the container holds enough stable.
The thermostat is assembled on the basis of a simple electronic circuit that does not contain hard to find parts. However, the accuracy of temperature so he high that the container can be used in summer as an incubator.
The power supply of the thermostat I have is with transformer 220x12 (TCE-70 or TCE-110).
To increase the power of the heater when the container or very low temperature on the street I entered into the scheme switch S1. To use it while not necessary. To control the operation of the thermostat by neon light bulbs: H1 indicates that the heater is on, and H2 and disabled serviceable. Glow or "silence" at the same time both light bulbs says about some malfunction.
The required temperature is set by the variable resistor R3.
Outwardly my tank, of course, plays "cellar" A. Christmas, but it is easier to make at home.