How to make a rectifier?
An electric current rectifier is called a specialdevice that is designed to produce an output DC electric current from the input AC current. In most rectifiers, filters are adopted to smooth the unidirectional pulsating voltages and currents that they create.
Why you need a rectifier
The main drawback of galvanic cells,feeding many electrical appliances, is a short period of their service. These inconveniences are especially noticeable, if loads require currents of great strength. To power electronic consumers, the electric current of an industrial power grid is best suited. But you can not connect the device provided for battery power directly to the network. It is necessary to convert the AC voltage to a constant voltage. Therefore it is very useful to understand how to make a rectifier. To power the equipment, voltages less than the mains voltage are usually used. This is achieved through the use of a power transformer. Then convert the alternating voltage to a constant voltage. Constant receive in two stages:
first, the variable image is converted into a pulsating one, i.e., varying from zero value only in one direction. After that, the filter converts the pulsating voltage into a constant voltage.
Types of rectifiers
- Half-wave - rectifier, consisting ofcapacitor and one semiconductor diode. Its design is very simple. It has a low coefficient of efficiency, therefore it is used only for powering low-power consumers.
- The full-wave rectifier consists of transformer windings, a capacitor and four diodes. Usually it is carried out on a bridge circuit. It is used for powering radio equipment.
The diodes are selected 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 the directories. The rectified current can not be less than the current that the load consumes. Diodes will not heat up if the rectified current is 2 times greater than the current required by the consumer. The reverse voltage consists of the voltage of the secondary winding and the voltage across the capacitor.
Manufacture of rectifier
- Take a half-liter glass jar or glass,plate with an area of 40x100 mm - aluminum and copper, a rubber tube with a diameter of 2 cm. Cut 2 cm from the pipe and put it on an aluminum plate. This is done because the electrolyte corrodes aluminum during operation. If you put rubber on it, it will protect the metal from corrosion, and the rectifier will last much longer.
- As an electrolyte we will use a solutiondrinking soda. It will need 5-7 grams per 100 ml of water. For the positive pole we take aluminum, and for the negative pole lead. The current will go if you connect the rectifier with a lead plate into the network. But the current will flow in only one direction. The aluminum plate will be a constant positive voltage pole.
- If an aluminum plate is included in the network, thenThe lead plate will act as a negative pole. It will be a half-wave rectifier through which only one half-cycle current flows. In this case, the flow of positive direction will flow.
- Full-wave rectifiers are used tofully use the voltage. The number of elements from which they consist depends on the required rectified current. Plug them into both phases of the mains.
- Use fuses when plugging the unit into the mains. Using a rheostat, you can adjust the voltage.
Calculation of the rectifier
- We define the alternating voltage of the secondary winding of the transformer:
U2 = BUn,
Uн - constant load voltage, V;
B is a coefficient that depends on the load current.
- Determine the maximum current flowing through the diodes:
Id = 0.5 C Iн,
Id is the current flowing through the diode,
Iн - the greatest value of a current,
C is a load-dependent coefficient.
- Define the reverse voltage:
Uobr = 1,5 Uн,
Uobr - reverse voltage,
Un is the load voltage.
- We choose diodes, in which the magnitude of the rectified current and the reverse voltage is higher than the calculated ones.
- Let us find the capacitance of the capacitor:
Сф = 3200 Iн / Uн Kп,
Cf is the capacitance of the filter capacitor,
Iн - maximum load current;
Un is the voltage on the load,
Kп - coefficient of pulsation (10 -5 -10-2).
Welding rectifier HP is used as aPower source when welding with any electrodes. It is used to exclude inter-current interruptions during welding, due to which a qualitative welding seam is obtained.
- The rectifier is universal, it can be used in the most difficult operating conditions.
- Insensitive to temperature fluctuations, changes in humidity, voltage drop in the network, dustiness.
- Has a low cost and is able to replace expensive installations.
Now you know all about who wants to know how to make a rectifier at home. This will allow you to solve problems on its absence on your own and with the least expenditure of funds.