I have made a home automation Arduino project using an HC-05 Bluetooth module. I want to power my Arduino from the main AC supply. Can I use a mobile charger/adapter to power it? Or should I buy a 12v adapter, and solder it to a barrel connector that fits the Arduino input?
Yes, you can. Both options are valid.
Yes you can use any options that you have mentioned in your question. One can say your question is your answer.
Can I use a mobile charger/adapter to power it?
The answer is almost yes: I use a phone charger myself.
Two reasons that it may not work out:
There are lots of unsafe, non-isolated, cheap phone chargers out there. Stay away from them. Use a brand name one that came with your phone.
Try to stay away from the QC2.0 or QC3.0. they are intelligent and negotiate the output voltage on the phone, up to 9 or 12v. They are compatible with non smart load but you don't want to run the risk.
Yes you can, simply connect the 5V VCC wire directly to VCC and connect GND to GND.
If using a 12V charger, then connect VCC to Vin.
DON'T FORGET GND TO GND
Yes you can, I tried with a sony 5V 850mA batery, it works.
I recommend you a multimeter if you haven`t had one before.