Microcontroller control of 220V AC power circuit diagram
1. For resistive loads
For example, a regular light bulb, generally around 30 to 40W, if using 220V AC to control the power on and off, a simple solution is to use a bidirectional thyristor for direct control. The BT137 can handle up to 7A and has a voltage rating of 600V, which is sufficient to drive the light bulb.
Alternatively, an optocoupler can be added.
2. For inductive loads
For example, electric motors, because they have coils inside, a 100W motor may draw up to 1000W at startup. Therefore, for these types of appliances, an additional RC snubber circuit should be added. If necessary, a varistor can also be included to ensure over-voltage protection, as the voltage can be very high during inrush. This prevents the thyristor from being damaged by the induced voltage generated when the power is switched on or off. Sometimes, an inductor is also connected in series.
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