![]() The transformer secondary voltage should be approximately. The transformer secondary rated current should be 1.2 times the DC current of the power supply. Since a capacitor input filter only draws current from the rectification circuit in short pulses, the frequency of the pulses is half that of a full-wave circuit, therefore the peak current of those pulses is so high that this circuit would not be recommended for DC power more than 1/2 watt.Ī full-wave rectifier uses only one-half of the transformer winding at a time. In this section we will explain the four basic rectification circuits that are used: Rectification Circuits for Regulated Linear Power Suppliesįrom our previous description, a regulated linear power supply is the most economical design for lower power, low ripple, and low regulation which is suitable for electronic applications. The disadvantages of this type of supply are that all of the transformers have to be custom-made and the complexity of the power supply does not lend itself to low production or economical low power applications. This DC is chopped to a constant high frequency voltage which enables the size of of the transformer to be dramatically reduced, and allows for a much smaller power supply. The AC voltage is rectified to an unregulated DC voltage, with the series transistor and the regulator. The schematic below is a simple block diagram and does not represent all of the components in the power supply. The switch mode power supply has a rectifier, filter capacitor, series transistor, regulator, transformer, but is more complicated than the other power supplies that we have discussed. ![]() These power supplies are heavier and will have more audible noise from the transformer resonance than regulated linear power supplies. The problems with using a ferroresonant power supply include that it is very sensitive to slight changes in line frequency and would not be switchable from 50 Hz to 60 Hz, and that the transformers dissipate more heat than conventional transformers. The ferroresonant transformer will supply a constant output voltage over a wide variation of the transformer input voltage. The output voltage has negligible ripple, very small load regulation, and high reliability, thus making it an ideal choice for use in low power electronic applications.Ī ferroresonant power supply is very similar to an unregulated power supply except for the characteristics of the ferroresonant transformer. The regulated linear power supply solves all of the problems of the unregulated supply, but is not as efficient because the 3-terminal regulator will dissipate the excess power in the form of heat which must be accommodated in the design of the supply. The ripple can be reduced by changing the filter capacitor to an IC (inductor-capacitor) filter but the cost to make this change would make use of the regulated linear power supply a more economical choice.Ī regulated linear power supply is identical to the unregulated linear power supply except that a 3-terminal regulator is used in place of the bleeder resistor. It will vary with the input voltage and the load current, and the ripple is not suitable for electronic applications. The disadvantage is that the output voltage is not constant. This type of power supply, because of its simplicity, is the least costly and most reliable for low power requirements. ![]() Unregulated power supplies contain four basic components: a transformer, rectifier, filter capacitor, and a bleeder resistor. ![]() This guide explains each type of supply, describes the principle of operation, and outlines the advantages and disadvantages of each. The differences between the four types include constant voltage output, cost efficiency, size, weight, and ripple. There are four basic types of power supplies used: Power Supply Design Notes Basic Power Supply Application Guide ![]()
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