24W 2A Switching Power Supply For LED Strip Light, 220V AC input, 12V output

Power supply 12V, 2A (24W)
Such a review has already been, but the power supply there is a little different, and I tried to focus more on the technical part.
I ordered these power supplies for led stripwho bought at buyincoins. LED strip feature:
Voltage: 12V

Number of LEDs: 60 (SMD 1210)
Total power: 3-4 watts
Current: 300 mA
According to the characteristics of the power supply should quietly pull 3 tapes with a margin. I decided to order two power supplies, since I have 6 LED strips.
When ordering power supplies, friends at workalso decided to order the same power supply. Total accumulated 5 power supplies. When making an order, I noticed that if you order more than 5, the price significantly decreases.
That is, when ordering 1-5 pcs, the power supply will becost $ 7.99, and if you order more than 5, then the power supply will cost $ 6.66. Idle arithmetic shows that it is better to pay 1 cent and take 6 power supplies than to order 5 power supplies at almost the same price.
5 x $ 7.99 = $ 39.95
$ 6.66 = $ 39.96
As a result, instead of the planned two power supplies I ordered 3 :).
Now power supplies are sold at a different price of $ 8.16 (6.8). The price of 5 (6) power supplies is now the same $ 40.8.
Power supplies came in the usual package, pasted inside with a pimple.

Each power supply inside was packed in its own box.

Three power supplies immediately gave to colleagues, and the remaining three left for myself
In an individual package there is a cut out window through which a sticker with characteristics can be seen:

By the way, on the website it was stated in the specifications that the input voltage is 220 + -20%, and on the label it is 220 + -15%.
We open the packaging. Type of power supply from different sides:



First of all we disassemble the power supply (unscrew the two screws)

If you look closely, the main components are similar to the power supply from a similar review, but there are differences.
Soldering to the four, under the elements that are attached to the body, thermal grease is visible. The case itself, which is the main radiator, is made of aluminum about 1 mm thick

A transparent dielectric strip is laid between the case and the board.

To monitor the temperature, I had to pin a thermocouple to the radiator. As a strut stuck in a piece of wood.

Radiator temperature reading without connections

I connect the power cable and instead of the load I put a 1.2 kΩ resistor (so that the current is small, approximately 10 mA). I turn on the power supply - the green LED lights up.

Power meter readings

This shows that at almost idle power supply consumes 3 watts per control circuit.
Here is the voltage that was initially set

Variable resistor set the voltage to exactly 12 volts

The power supply unit worked for some time at idle, the temperature of the radiator quickly stabilized at around 36 degrees.

Then I decided to remove the temperature characteristics at the maximum allowable current. At work, I took several powerful resistors and assembled a 6 Ohm load from them.
Assembled stand, on the multimeter the initial temperature

Briefly connect the load through the ammeter

As you can see, the current is almost 2A (59 mA is missing). I think that it is not very important to remove the temperature characteristics
Turn on the power supply to the network. Power meter readings

Mains voltage

Every 5 minutes I recorded the temperature readings.
Measurements took 1 hour, since during this time the temperature was set. All data is tabulated (at the bottom of the review there is a screenshot)
After an hour of experiments, the temperature settled at around 64 degrees. The power supply case is hot, although the hand suffers.

Then I decided to test the power supply with the same load, but I decided to close the power supply. As a cap, I decided to use part of the juice box.

In this mode, the power supply is heated to a temperature of 81 degrees!

Naturally, in this mode, the power supply can not be operated. For everyday use, it is better to use a load of two times less.
For the tests I decided to take three LED strips. Current through one tape

The total current of about 960 mA.
Power taken from the network

The power supply in this mode is heated to 50 degrees.

Similarly removed the characteristics for two LED strips and one LED tape. The power supply is heated to 48 and 45 degrees, respectively.
Thinking over my head, I decided a littleupgrade power supply. In the desktop I found a cooler from an old vidyushka of 50x50x10. After removing the case, I screwed the fan to the case with screws. At a voltage of 12 volts, the fan is a little buzzing, so I soldered a 100 Ohm resistor to a single wire of the cooler. The fan began to rotate a little slower, but now it has become silent. I myself connected the fan to the output of the power supply.

In this mode, the power supply with a load of 2A warmed to 32 degrees! I thought the temperature would be higher. Very good indicator.
Pivot table and graphs.

After all the experiments, I decided to see how the input voltage affects the output. For these experiments, I had to carry the power supply to work, where there is a powerful latr.
I took the characteristic at different loads (10mA and 2 A), but the graph turned out to be the same.

From the characteristics you can see that the power supplyIt works steadily at a voltage of 90 to 256 V. Above, the voltage could not be raised, the latr worked at the limit. Less than 90 V, the power supply starts to hum at high frequencies, and the output voltage drops sharply.
At work, the power supply lay on with a current load of 2 A for more than three hours without any consequences.
Efficiency calculation

It is seen that at a current from 1A to 2A, the efficiency varies from77 to 79%, and at a current of less than 1A efficiency drops. This is due to the fact that the power of the circuit takes 3 watts. When reducing the load current efficiency will tend to zero.
Advantages and disadvantages.
Pros:
1) Miniature (8.5 x 5.8 x 3.3 cm)
2) Ability to adjust the output voltage, approximately from 11 to 13 volts
3) Power supply operation indicator
4) Silent
5) High input voltage range
6) Stable output voltage
7) The ability to screw the power supply to anything, there are holes on the body.
Minuses:
1) it is very hot at maximum current
2) one block for input and output voltage
3) on the aluminum case there are places where the technological film is not peeled off
Brief conclusions:
This power supply can be used without active cooling only with a load of no more than 1 A. For a serious load, it is better to use power supplies more efficiently.
Other power supplies from the same seller