km said:
Is it possible to display the results for a bigger voltage range? ( i.e. -240V-240V) :roll:
Yes, you just need to use a resistive attenuator on the front end to give the voltage you need. If you want to display positive and negative, as well as just positive, probably the easiest way is to use an opamp on the input, fed from a split supply. Feed the output of the opamp through a resistor to the input of the A2D, and connect an identical resistor from the input of the A2D to the positive reference - this will give half scale reading at zero volts in, full scale readng at maximum positive in, and zero reading at maximum negative in.
What additional components OR any circuits do I need to in order to build this project :?:
I am not allowed to use a built-in ADC PIC in this project, so which type of ADC chip is suitable for me? :idea:
Pretty well anything would do, you don't need to get carried away with high resolution - an eight bit A2D gives better than 0.5% resolution - which will be more than the rest of the circuit.
Using a PIC with inbuilt 10 bit A2D would make life nice and easy, it's a pity you can't do that!.
How about using a PIC 12F675 (8 pin FLASH PIC with 10 bit A2D) as an A2D? - would that be allowed? - treat it just as an A2D and feed to your 16F84 for the display and calculations.
Is there any website that related to my project and where I can find the programming code for my PIC for this project?
My tutorials show how to drive an LCD and keys, you might find them helpful - also one shows how to connect to an I2C A2D, but that's probably not your best solution!.
Update:
Just remembered something I forgot, you will need a low-pass filter on the input stage, it's vital that your sampling rate is higher then the maximum incoming frequency - at least double, preferably more!. Otherwise you get anti-aliasing distortion which will complete ruin any readings.
I would also suggest your biggest problem is going to be calculating RMS values, this is likely to take a fair amount of maths.