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How to make a rectifier?

Rectifier of electrical current is called a special device, which is designed to obtain the output constant electric current from the input AC current. Most rectifiers accept filters to smooth out the unidirectional pulsating voltages and currents they create.

Why do I need a rectifier

The main disadvantage of electroplating cells that power many electrical appliances is their short lifespan. These inconveniences are especially noticeable if the load requires high currents. The electrical current of the industrial power grid is best suited for powering electronic consumers. But you can not connect a device provided for powering the battery directly into the network. It is necessary to convert the AC mains voltage to DC. Therefore, it is very useful to understand how to make a rectifier. To power the equipment, voltages less than the network voltage are usually used. This is achieved through the use of a power transformer. Then convert the AC voltage to DC.Constant receive in two stages:

first, the variable image is converted into a pulsating, that is, changing from a zero value in one direction only. After that, the filter converts the pulsating voltage to a constant one.

Types of rectifiers

  • A half-wave rectifier consisting of a capacitor and one semiconductor diode. Its design is very simple. Differs in small efficiency, therefore it is used only for food of low-power consumers.
  • A full-wave rectifier consisting of windings of a transformer, a capacitor and four diodes. It is usually carried out according to a bridge circuit. It is used to power the radio equipment.

Diodes are chosen according to the following parameters: the value of the constant (rectified) current at the output of the rectifier and the value of the reverse voltage. These parameters are taken from reference books. The rectified current cannot be less than the current that the load consumes. Diodes will not heat up if the rectified current is 2 times larger than the current required by the consumer. Reverse voltage consists of the secondary voltage and the voltage across the capacitor.

Rectifier manufacturing

  • Take a half-liter glass jar or glass, a plate with an area of ​​40x100 mm - aluminum and copper, rubber tube with a diameter of 2 cm. Cut 2 cm from the pipe and put it on the aluminum plate. This is done because the electrolyte corrodes aluminum strongly during operation. If you wear rubber on it, it will protect the metal from corrosion, and the rectifier will last much longer.
  • As an electrolyte, we will use a solution of baking soda. It will need 5-7 grams per 100 ml of water. We take aluminum as the positive pole and lead as the negative pole. The current will go if you connect the lead plate rectifier to the network. But the current will go only in one direction. The aluminum plate will be a constant positive voltage pole.
  • If the aluminum plate is included in the network, the lead plate will act as a negative pole. This will be a half-wave rectifier through which the current flows for only one half cycle. In this case, positive current will flow.
  • Full-wave rectifiers are used to make full use of the voltage. The number of elements of which they consist depends on the required value of the rectified current.Connect them to both phases of the grid.
  • Use fuses when plugging in the unit. With the help of a rheostat, you can adjust the voltage.

Rectifier calculation

  • We define the alternating voltage of the secondary winding of the transformer:

    U2 = B Un,

    Un - constant load voltage, V;

    B - coefficient that depends on the load current.

  • Determine the maximum current flowing through the diodes:

    Id = 0.5 C In,

    Id - the current going through the diode,

    In is the largest current value

    C - coefficient depending on the load.

  • Determine the reverse voltage:

    Uobr = 1,5 Un,

    Uobr - reverse voltage

    Un - load voltage.

  • Choose diodes, in which the magnitude of the rectified current and reverse voltage above the calculated.
  • Find the value of the capacitor capacitance:

    Cf = 3200 In / Un Kp,

    SF - the capacitance of the filter capacitor,

    In - maximum load current .;

    Un - voltage on the load,

    Kp - the coefficient of pulsation (10 -5 -10-2).

Welding rectifier

The VD welding rectifier is used as a power source for welding with any electrodes. It is used to eliminate inter-breaks during welding, which results in high-quality welding seam.

  • The rectifier is universal, it can be used in the most difficult working conditions.
  • Insensitive to temperature fluctuations, changes in humidity, voltage drop in the network, dust.
  • Reliable
  • Is durable
  • It has a low cost and is able to replace expensive installations.

Now you know everything about who wants to know how to make a rectifier at home. This will allow you to solve the problems of its absence independently and with the lowest cost of funds.


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