With the switch SA2, the heating element can be turned on forcibly, regardless of the signal of the control unit. It may be necessary to monitor the safety of incandescent lamps or forced ventilation of the vaccine.
Adjustment of the heat stabilizer is reduced to finding the upper temperature (to) and lower (tH) thresholds, which are connected to the thermistors features according to the algorithm in some limited volume and there is measured the temperature with a mercury or alcohol thermometer. And the recommended sequence is that initially this volume placed the first sensor. Next, set the temperature in accordance with the selected value of tH switch. The thermistor R7 is kept in such an environment at this temperature for about 10 minutes, after which, by changing the position of the movable contact of the variable resistor R5, to achieve operation of the device and turning on the heater RH.
then heat the environment to a limited extent by some value (e.g. 2 °C) and placing next to the first the second sensor is a thermistor, adjust already on R10. This produces a time delay and changing the position of movable contact of the variable resistor R8, to achieve off of the heater R
The adjustment must be repeated several times, not forgetting the safety rules, because all the elements of the circuit are under voltage of 220 V.
The control unit is placed in a locked box separate from the heater lamps and sensors-thermistors.
Now to replace the parts. There are a lot of choices. In particular, diode Assembly КЦ402Г allowed to replace a similar КЦ402В, КЦ405Г and КЦ405В, wherein the location of the contact pins. A high voltage (with the indices “A” and “b” in the name) is also quite acceptable, but not from the series КЦ403 and КЦ404 — they contain two independent rectifier bridge. In extreme cases, we can recommend and a home-made Assembly, such as power diodes КД226В brands, КД411Г, Д231 or 2Д215А.
Cobalt-manganese thermistors KMT-4 valid to replace the copper-manganese MMT-4. However, the latter have a smaller value of temperature coefficient of resistance and therefore lower sensitivity.
Chip К176ЛА7 with four logical elements “2I-NOT” designed for 9-volt supply voltage, while still functioning at 5-10 V and consumes a very small current. She has good analogues, for example, K561LA7, К511ЛА1 and К511ЛА5.
Variable trimmer SPb can be replaced by SDRs, however, the latter is worse than the humidity and constant value of the set resistance.
Well, instead of Д814Б (Uci = 9, 1С1 — 36 mA) is quite acceptable other Zener diodes. For example, D810, Д811, Д814А. The same can be said about the replacement of the transistor KT315 and КТ315Б on ГТ341 (with any letters) or a semiconductor triode КТ3102А.
In conclusion, a few remarks about the features and operation of mini greenhouses. Because with all func-
functional similarity the vaccine is fundamentally different from traditional cellars, and the basis of this difference in ventilation. The first of these it is, essentially, missing. As air exchange occurs, it would seem, only when the cover is opened.
In fact, the air exchange with the external environment when the heat stabilizer is constantly happening: when I turn on the heating element temperature in minibaseboard a few increases and a portion of the air exits from the enclosed space to the outside, and the cooling of the internal volume, on the contrary, heading back inside.
And the greater the temperature difference, the more is the switching of the heater, the more intense is the “breath” of the vaccine. The reflection of this fact is extremely important since it allows to avoid increasing the humidity within the storage and rotting in it products.
But the possibility of maintaining temperature and humidity at the required level for use, however, is not unlimited. It turns out that putting vegetables in storage is desirable when the outside temperature is below + 10 °C. And it is necessary to keep the wet veggies in the thermocontainer did not fall.
For getting rid of moisture allowed to use a forced operation of the heating element when the lid is opened. This will allow the layer to dry vegetables in cold box due to suction of outside air and exhaust moist, passed through the layer to the outside. Such an operation is possible even without the cost of electricity: nastavi housing of the heating element pipe, obtain the natural extract.
At low temperature the ambient air humidity inside the cold box is always higher than the humidity of the outside air, so that when the “breath” of the vaccine is freezing of the joint cover. This is a natural process, and to deal with it is not necessary. And the cover is not frozen to its nest, it is enough to insert into the gap between her and the corps of strips of plastic film.
Finally, the last tip. The best results — the maximum uniformity of temperature throughout the storage space, and small deviations from steady state is achieved when the vaccine when continuing the heater gives exactly as much heat as required.