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Microwave ovens have become part of our everyday life. Do you know what the scheme of a microwave oven is, how it works? We invite you to explore this issue.
Varieties of microwaves
All microwave ovens are divided into two types: with electromechanical or, more simply, mechanical control, and with electronic control. The former are distinguished by a simpler system design and, accordingly, a lower price. The latter have a more “friendly” interface and are more convenient to use.
Mechanical control
Most microwaves with mechanical control are almost the same and have no fundamental differences.
Here is an electrical / circuit diagram of a Samsung RE290D microwave oven with electromechanical control.
The “heart” of any microwave oven is the magnetron. It is he who generates ultra-high frequency (MW) oscillations, which heat the products placed inside the microwave oven or, as it is also called, microwave oven.
Magnetron – from the English magnet (magnet) – “came” into everyday life from … radar. It was there that this generator radio tube was first used.
In order for the magnetron to work, it is necessary to apply a cathode heating voltage (for most magnetrons 3,15 Volts) and a high anode supply voltage (from 2000 to 4000 Volts).
- These voltages are taken from the secondary windings of the HV TRANSF transformer;
- The NOISE FILTER prevents impulse noise from the microwave oven from entering the mains;
- The TIMER MOTOR counts down the cooking time. The FAN MOTOR electric motor with an impeller installed on its axis cools the magnetron, which becomes very hot during operation;
- Also included is a motor not shown in the diagram that rotates the turntable, and a LAMP lamp that illuminates the oven chamber.
Combined heating
Separate models of microwave ovens are additionally equipped with heating elements (tubular electric heaters) and have combined heating – microwave plus thermal. This helps produce a crispy crust on foods that is not present with pure microwave heating.
Pulse modulation
The output power of the magnetron and, accordingly, the heating of the products is regulated in a way that is also borrowed from radar. The magnetron turns on from time to time, alternating with pauses. The more it “idle”, the less heating of the products. In the literature, this method is called pulse modulation (PM).
In the above diagram, the magnetron is switched on and off using the VPC SWITCH switch, which is mechanically connected to the timer motor.
ектронное авление
The executive / power part of the electronically controlled microwave circuit is no different from that shown above. The only difference is that an electronically controlled microwave does not have mechanical contacts and its operation is controlled by a microprocessor and integrated circuits. The role of contacts is performed by electronic keys – triacs. Moreover, in case of emergency, it is possible to replace the electromechanical control system with an electronic system and vice versa.
In practice, this is not done for design reasons – a large amount of plumbing work is required and there are differences in the size of these control systems.
uniformity
Thus, we can say that all microwaves, as leading brands – Samsung, Bosch, Gorenje, Daewoo, Panasonic, Elenberg, Scarlett, LG – and the manufacturers of the “second tier” – Digital, Trony, and so on – have the same device and a fairly large interchangeability of constituent elements. To illustrate, we will show photographs of microwaves with different types of control.
This is an electronic oven.
And this is with a mechanical one. As you can see, the two main types of ovens are easy to distinguish from each other even visually. But at the same time, according to the schemes, their design is slightly different.