Опубликовано 2013-03-19 15:52:18 автором Ruslan
Control AC load
Once it took me by a microcontroller to control incandescent (then I did a control circuit for the incubator ) . The first thing that comes to mind - it's something like this It's simple , you can adjust the brightness of the lamp serving leg transistor PWM signal ( no need to do the null detector ) . But this scheme has its disadvantages . Firstly, this loss effect transistor and a diode bridge . However, there is a better solution ( in terms of efficiency ) - this control with triac or thyristor .
Thyristor - passes current in one direction only , as a diode , but it is distinguished from the diode control terminal . To thyristor opened , you need to submit a current control terminal otkrytiya.Togda it opens and will carry a current in the forward direction as long as there is a direct voltage napryazheniya.Esli remove or change its polarity , then the thyristor will close and open it again to have supply current to a control terminal .
Simistor is different only in that it passes current in both forward and reverse , in fact they are two anti- parallel connected thyristors . Positive wave sine wave passes one negative - on the other. But allows only the presence of the control signal. If it is removed, the next half-wave thyristor both closed. Still there is one hitch : Commuting we high-voltage circuit 220 , and the microcontroller have 5 volts , then you need to do for a good ending. Make it so that between them did not beat a direct electrical connection. It is best to separate them using a triac optodrayvera . capacitor voltage must be> = 400v.V optodrayvere signal is LED , so you can easily connect it directly to the leg MK and not be afraid of different pickups in the high voltage circuit .
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