Is there a mining machine in Hangzhou electric appliance city

1. First of all, we need to understand that we buy family miner in order to save money and make money. To buy a family miner, it depends on who can get back the money quickly in a reasonable time. For the cost recovery of mining, it depends on the price and mining capacity of the miner. In the two miners with the same mining capacity, the cost recovery of the miner with lower price is faster; In the same price of mining machine, mining ability strong back faster
I compared several mining machines with several Jiabao intelligent robot terminal equipment with Computing Center, which is the best combination of price and mining capacity.

2. Now it is 2014, and the professional LTC mining machine has come out, so the computing power of the whole network is increasing rapidly<

the cheaper one available in China is Zeus miner. The lowest price is less than 300 yuan, which is equivalent to the speed of the previous two 280x graphics cards. It turns out that this video card alone will cost 4000 yuan, so we have to sigh about the rapid technological upgrading.

3. The term of employment refers to two years after graation. Your term of employment ends on June 30, 2009, so it is still in the term of employment. Files can and should be transferred out to calculate length of service. When transferring files, you should consult the human resources department of your company. Units without personnel management authority usually handle personnel agency for employees. If there is no human resources department, ask the person in charge of personnel. If not, you can only handle personnel agency proceres as a talent exchange center. The annual cost is about 120 yuan.

4. I'm also a fresh graate. Here are my personal suggestions and online collection:
it's better to put them in the talent market, because after graating from University, our files belong to cadre files. If we call back to our hometown directly, we can't get them in some policies. In addition to the record and verification of a person's life, archives also shoulder some other important tasks, such as identification of personal needs, judicial notarization, declaration of professional title, application for postgraate, issuance of personal certificate, handling retirement proceres, entry examination of new units, public servants, political examination of public institution recruitment, examination and confirmation of length of service, examination and approval of length of service after retirement Going abroad for political examination, insurance, etc. Without archives, some rights and interests of indivials will not be protected
archives are real records of personal experience; The archives show a person's administrative subordination; Archives are the basis for the center to provide relevant personnel services for indivials
according to the person in charge of the provincial college graates' Employment Guidance Center, at present, the state generally adopts three methods for the archives of unemployed or flexible graates

1 transfer the files to the place where the students come from and receive them from the local ecation bureau or personnel bureau. This method is more suitable for graates who are ready to work in the scope of the source area and those who do not want to work temporarily
2 keep the files in the school. According to the relevant regulations, the registered permanent residence and files of the graates who have not implemented the unit at the time of graation are allowed to stay in the school for two years. After the work units are implemented, the registered residence and archives will be relocated to the location of the work units. For those who apply to stay in school for more than two years and have not implemented the work, the school will move their files and registered permanent residence back to the place of origin. This way is suitable for graates who are willing to work but not yet employed
3 transfer the files to the agent of employment guidance center or talent exchange center. This way is more suitable for graates who are preparing for postgraate entrance examination, entrepreneurship and flexible employment. Xiao Wang is more suitable for this way to deal with archives, but he needs to pay a certain management fee to the archives management side

in addition, I entered the company directly when I graated, and the files can be directly transferred to the company I went to! The company has the union specialized management! Hope you can have a good mood, good job, also hope my answer can help you a little!

5. The main consideration is the input power range and power. These two parameters are difficult for the user to choose. If you choose small, it will not be enough. If you choose large, it will be a waste. Of course, if you have enough silver in your pocket, it doesn't matter. I like it. Generally speaking, if the power of your equipment (such as computer, air conditioner, etc.) is 5000W, you can't choose 5000va when you choose the voltage regulator. Generally speaking, you should choose at least 7.5kva-10kva. That is to say, the voltage regulator should be at least 1.5 times of the power used
some users also consider that they will use more switching devices in the future. I don't think it's necessary to buy a high-power voltage regulator at one time. Generally, the manufacturer guarantees the voltage regulator for one year. The voltage regulator belongs to electronic and electrical procts and has a service life. The devices will age. I think it's enough at this stage

it's not easy to answer. If you have any help, please take it. Thank you!!

6. There are two main points:
1) input voltage range of voltage regulator, select voltage regulator according to your voltage range
2) when choosing a voltage regulator, consider the margin, which is generally about 1.5 times of your electrical appliance. If it is too big, it may not be enough.

7. Voltage regulator selection method
1. Capacity safety factor
AC regulated power supply takes the output apparent power (kVA) as the nominal rated capacity, but generally, the load is not purely resistive, that is, the power factor cos ￠ 1, the actual output active power of voltage regulator kw = capacity (kVA) × COS￠ Therefore, in the actual selection, the regulated power supply should be reasonably selected according to the rated power, power factor and load type of the electrical equipment, and its output power should have an appropriate margin, especially for the impact load selection, See the table below for the specific selection safety factor
load nature equipment type safety factor selection regulated power supply capacity
pure resistive load incandescent lamp, resistance wire, electric furnace and other equipment 1.25 ~ 1.5 times the total load power
inctive and capacitive load fluorescent lamps, fans, motors, water pumps, air conditioners, computers Refrigerator and other 2 ~ 3 times or more than 2 ~ 3 times the total load power
in the environment of large inctive and capacitive load (such as motor and computer), the starting current of the load should be considered to be particularly large (up to 5 ~ 8 times of the rated current), so the voltage regulator capacity should be 2.5 ~ 3 times of the load power
for example: one three-phase motor with 2.2kW and one motor with 5.5kW, when voltage regulator is selected, the capacity ≥ (2.2kW + 5.5kW) × 2.5 = 19.25 KVA, that is to say, at least three-phase sjw-20 KVA voltage regulator should be selected< When the input phase voltage is lower than 198v, the output capacity of the self coupling voltage regulator (single-phase 0.5kva ~ 3KVA, 10K horizontal and below, three-phase 9KVA and below) begins to decline; When the input phase voltage is equal to 160V, it will drop to 50% of the rated capacity of the voltage regulator. Therefore, at the low end of the power supply voltage, special attention should be paid to rece the load derating, so as not to overload and burn the voltage regulator
the voltage regulator can output two kinds of voltage at the same time: 220 V and 110 v. But even if it is all output by 110V, the load of the regulator should not exceed 50% of the rated capacity, otherwise it will be overloaded
most computers are 350W now,. It is recommended that you choose a voltage regulator of more than 8000w
attention! The computer should use servo voltage regulator or other uninterrupted power supply voltage regulator.

8. Most system design engineers may agree that the linear regulator is the easiest one to use, and for this reason, it is also the most popular one among system design engineers. However, the requirements of the new generation system are very strict, so the high-performance system using only linear voltage stabilizing technology will be restricted, so it is difficult to give full play to its performance. This development trend brings out the following questions: what kind of technical support can system design engineers get when they conceive new procts? What are the advantages and disadvantages of DC / DC power conversion system with linear voltage stabilizing technology? Is it superior to the power conversion system with other line layouts? What are the technical limitations? If compared with the same application, which type of LDO has higher efficiency? Does the linear regulator of different manufacturers have different advantages and disadvantages? It seems that these questions are very simple. In fact, the answers to these questions are more complex than we think. Because there are so many important factors and technical parameters that need to be considered, and the importance of relevant factors is often ignored, system design engineers must be careful when making choices. As the power supply requirements of new procts are becoming more and more strict, the area of circuit board is also shrinking, and the system must guarantee the most basic performance, we must select the appropriate low voltage drop regulator for the new procts. A good low dropout regulator can solve many application problems; If the regulator is not selected properly, the whole design can not be implemented

heat dissipation, efficiency and packaging

the input power of the linear regulator can not be completely output from the output port, and the difference between the two will turn into heat dissipation. The power dissipation (PD) can be roughly estimated according to the following formula:

PD = (VIN – VOUT) * IOUT

in order to calculate the power dissipation more accurately, we must include the variable VIN * IQ. The total power dissipation can be calculated according to the following formula:

PD = (VIN – VOUT) * IOUT + VIN * IQ

if the voltage of 5 V is reced to 1.5 V (quiescent current is 300 MA) according to the above two formulas, Then the power dissipated by the linear regulator into heat energy will not be less than:

(5 – 1.5) * 0.35 = 1.225w

should this power consumption be considered as high or low? We can't judge this problem too early. We must find out the functional relationship between these variables and the temperature rise according to the type and area of chip package and circuit board (if surface mount package is used), so as to calculate how much the temperature rise will be caused by 1.225w power dissipation. In this way, we can make a more comprehensive judgment to determine whether the power dissipation of 1.225w is high or low. System design engineers generally like to use the smallest package, but the thermal resistance value of this kind of package is very high, so the heat dissipation ability is also the worst< The qja values of standard SOT-23 and SC-70 are between 200 degree / W and 400 degree / W. The qja values of SOT-223, TO-252 (DPAK) and other unshielded solder ball SMD packages (including PSOP and etssop) are between 50 degree / W and 90 degree / W

generally speaking, only larger packages (such as TO-220 and to-263) have ideal qja values, which are between 40 degrees / W and 60 degrees / W. In general, this is the relationship between package size and temperature rise, which is applicable to all packages except LLP. Because of the special internal structure of LLP package, for example, the chip is placed on the metal surface in the way of facing up and bottom down, and the metal surface is placed at the bottom of the package without any masking, the thermal resistance of this kind of ultra small package is extremely low, even comparable to that of larger packages. It is the only ultra small package with such low thermal resistance at present

what is the effect of the above figures on the system temperature? If the power dissipation is PD = 1.225w, theoretically, the temperature of 2.85mmx3mm SOT-23 package will rise at least 300 degrees. The heating temperature of 6.6mmx9.7mm DPAK package will be 80 degrees higher than the ambient temperature. Only 10.4mmx14.35mm to-263 package or 2.9mmx3.3mm LLP package has a small temperature rise (50 degrees). If the system design engineer knows how to select the appropriate linear regulator package, he can roughly know whether switching regulator is needed

quiescent current (IQ) and complementary metal oxide semiconctor (CMOS) low voltage drop regulators

quiescent current (IQ), also known as operating current or grounding current, is one of the important factors to be considered when designing low power, low operating current and battery powered electronic procts. Whenever we talk about 1a, 2A or 3A constant current loads, do we ignore the important role of quiescent current? System design engineers often ignore this problem - in fact, ignoring the importance of quiescent current can cost a lot. The quiescent current of the system may increase greatly with the increase of load current, and the increase depends on the process technology adopted by the LDO. For example, the quiescent current of 3A load current may exceed 200mA. In addition, the quiescent current of CMOS LDO is very low, and it is not affected by the load size. If the full load current is 3a, the quiescent current is generally only 3mA to 15mA; If the load current is 1A / 2a, the quiescent current is between 100A and 6mA Refer to the function diagram of power supply current and load current in Figure 1. The two 150mA low dropout regulators in the figure are manufactured by CMOS and bipolar technology respectively.)

if the output current is 3a, is the quiescent current 200mA or 6mA so important? As mentioned above, the total amount of power dissipation is a decisive indicator to judge whether the LDO solution is feasible or not. Although in the formula for calculating power dissipation, the first variable will change with different applications (that is, this variable depends on the input voltage and output voltage), the second variable completely depends on the static current, And it may be an important factor of the actual power dissipation. Taking 3.3V input voltage as an example, 200mA quiescent current will increase the power dissipation by 660MW. For such a high power dissipation, the design may need to use switching regulator. If the quiescent current is as low as 6mA, the power dissipation will only increase by about 20MW, which is negligible, so the total power dissipation is almost unaffected. With such a low quiescent current, the linear regulator can still play its role, so as long as the quiescent current is low enough, the system design engineer can still choose CMOS linear regulator

before deciding which quiescent current value to choose, it is better to refer to the full load value in the inner page of the data sheet. At present, operators like to list the lowest or no-load quiescent current value in the top column of the data sheet. Engineers often think that this is the full load value, which is easily misled by this column<

voltage drop and low input voltage of LDO

is the voltage drop of LDO really low? We should think about it again and again. Although it is indicated in the proct specification that the required voltage drop is 100mV, this value is only applicable to some applications. For example, if the input voltage is larger than the minimum input voltage of the voltage regulator chip, the voltage drop may be only 100mV. However, if the system needs an output voltage of 1.2V or lower (such a low output voltage is required in many applications), The voltage regulator needs no less than 2.5 V input voltage operation. For example, the typical voltage regulator with input voltage between 2.5 V and 5.5 V needs more than 2.5 V input voltage. In this case, the real voltage drop is: 2.5v-1.2v = 1.3V. Theoretically, the above system should be able to perform normal functions, but the power dissipated into heat energy will account for a large proportion

if the input voltage of the system can be changed to 1.5V or 1.8V, the efficiency can be greatly improved, and the temperature rise and heat dissipation can be reced by using a low voltage drop regulator indicating a 100mV voltage drop. Take the 2.5V low dropout voltage regulator as an example, if 500mA load is used:

power dissipation = (2.5-1.2) * 0.5 = 0.65w

but the same system uses the 1.5V low dropout voltage regulator:

power dissipation = (1.5-1.2) * 0.5 = 0.15w

the power dissipation difference between them is 500MW, which is not small, Can we just ignore it?

9. The voltage regulator is selected according to the power and voltage
genuine Shanghai Delixi high precision automatic voltage regulator package
my user name is Wangwang name..

10.

According to the capacity and type, voltage regulators are generally divided into: single three-phase high-precision voltage regulator, compensation voltage regulator, precision purification voltage regulator, contactless voltage regulator, numerical control voltage regulator and oil immersed voltage regulator, etc! To buy a voltage regulator, you should choose the right one according to the type and load size of your own equipment

I'll recommend you a high-precision AC voltage regulator

for more details, please see the above figure