I'm doing a home project that will switch an appliance ON or OFF based on a signal from a microcontroller. I'm almost done designing the control circuit and the microcontroller currently sets one of it's pins high as long as the appliance is supposed to be ON, and clears otherwise. I don't have much experience working with household electricity so I'm not sure how to properly interface my circuit with the appliance and the AC power line. I'm thinking of using a relay driven by the output pin of the microcontroller (maybe using a transistor to switch enough current to energize the relay?). The circuit will be placed directly between the appliance and the AC powerline.
The requirement for on/off power switching is that the power circuit has to be able to handle 110 V rms at 5 A minimum.
The other issue is that I'm using a 9 V battery and a 5 V voltage regulator to power the electronics. Since the circuit will be directly attached to the wall socket, I would like to eliminate the 9 V battery and use the controlled AC line to power the control circuit as well. However, I'm not exactly sure how to go about controlling the AC line while at the same time powering the control circuit (in parallel maybe?). Also I would have to convert that AC into low voltage DC and so far I haven't found any reasonably priced transformers with enough output current (0.4A or more).
I would basically like to know the following:
1. What is the proper way of of controlling an AC appliance based on a signal from a microcontroller?
2. Do I need to worry about things such as AC noise, circuit protection, isolation, ..etc?
3. How to power both the control circuit and the external AC appliance from the same wall outlet? I don't think using a battery is the best way.
Attached is my current implementation. Any help would be greatly appreciated.
The requirement for on/off power switching is that the power circuit has to be able to handle 110 V rms at 5 A minimum.
The other issue is that I'm using a 9 V battery and a 5 V voltage regulator to power the electronics. Since the circuit will be directly attached to the wall socket, I would like to eliminate the 9 V battery and use the controlled AC line to power the control circuit as well. However, I'm not exactly sure how to go about controlling the AC line while at the same time powering the control circuit (in parallel maybe?). Also I would have to convert that AC into low voltage DC and so far I haven't found any reasonably priced transformers with enough output current (0.4A or more).
I would basically like to know the following:
1. What is the proper way of of controlling an AC appliance based on a signal from a microcontroller?
2. Do I need to worry about things such as AC noise, circuit protection, isolation, ..etc?
3. How to power both the control circuit and the external AC appliance from the same wall outlet? I don't think using a battery is the best way.
Attached is my current implementation. Any help would be greatly appreciated.
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