Which is better, an old transformer power supply or a switching power supply?
Switching power supply and the old transformer power supply each has its own characteristics and scope of application, who can not completely replace each other. Here are 5 aspects of a comparison.
1. First of all, the transformer power supply failure rate is low, strong overload resistance, especially instantaneous severe overload will not lead to transformer damage. The core component of the switching power supply is a semiconductor tube with poor overload resistance, which directly leads to its poor overload resistance, while the switching power supply consists of a large number of electronic components, the structure of the complexity of the failure rate is high and difficult to maintain.
2. Transformer power supply is only suitable for AC, so it is widely used in the power system. Switching power supply is a DC to DC conversion, in this regard can never replace the transformer. Of course many electrical appliances also use transformer power supply, such as the past 12-inch black and white TV set. It is a transformer to reduce the voltage, and then rectified and filtered into DC, and then regulated by the linear circuit to the TV power supply, due to the regulator circuit requires a large voltage difference, which brings another problem is very low efficiency.
3. The efficiency of the transformer itself can be very high, especially large transformer efficiency up to 95% or more, but this is only limited to directly to the AC load power supply. And almost all electronic equipment to DC power supply, such as transformer power supply should be added another rectifier and linear voltage regulator circuit. For example, the 12-inch black and white TV mentioned above, the overall efficiency of the power supply is only about 60% or so, for the modern computer 3.3 and 5v tens of amperes of power supply, if you use a transformer plus linear voltage regulator mode, almost impossible. Because of the voltage difference required to regulate the voltage, even if only 1v also have to waste a few tens of watts of power. As a switching power supply is different, because the work in the high-frequency switching state so the efficiency is very high, only need to control the ratio of the duration of the two states of on and off, can complete the task of regulating the voltage.
4. Volume and weight are not the same. Transformer power supply is composed of iron core and coil is very heavy, such as 100W transformer weighs 3.13Kg, such as power supply to the DC appliances plus rectifier and regulator part, together with the volume and weight is very considerable.
The 100W switching power supply from 220v AC to DC regulated output of the overall device is only 0.38kg, a difference of nearly ten times. In addition, the switching power supply can also be used according to the needs of the occasion, designed as ultra-thin or long type, the transformer can only be made into a bulky iron lump.
5. Switching power supply due to the high operating frequency and not sinusoidal, so it will produce a lot of harmonics, internal interference with the load external pollution of the power grid, and now has become a public nuisance. Although the efforts of scientific and technological personnel have improved, but still unsatisfactory. And then look at the transformer plus linear voltage regulator programme, although the efficiency is not ideal, but the output is pure interference is small, there is a certain market.
