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Simplest way of measuring and displaying 120VAC using PIC16F877A

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chr0n

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If i wanted to measure and display 120VAC (Voltage, Current, Power, AC Wave, etc...) from a receptacle in my house using a PIC16F877A. What would be the most economical and simplest approach? This is for a class project so I was just curious.
 

PIC16F877A Question

use voltage divider to scale down 120VAC to 0-5V.

Use rectifier, then the divider. If you want to show the full waveform on some graphic LCD, then don't use rectifier, but you'll need to finetune the divider to get best results. I sugget to use 1:100 with 87k and 1k fixed resistors and 20k multiturn pot.
 
Re: PIC16F877A Question

This is AC voltage so simple divider will not be enough. You'll need some level shifting as well because the A/D converter in PIC cannot measure voltages below ground (Vss).
 

Re: PIC16F877A Question

janni8 said:
This is AC voltage so simple divider will not be enough. You'll need some level shifting as well because the A/D converter in PIC cannot measure voltages below ground (Vss).
Click to expand...

yeh, the simplest is the diod and you should use the buffer OpAm before the uC.
Good luck for U !
 

Re: PIC16F877A Question

We made a measurement AC with voltage-frequence converter on AD654.
Next one is optocoupler 6N137. Microcontroller PIC measure period imulses.
Low cost and simple.

Let me know, if you want sheet.
 

Re: PIC16F877A Question

sure, could you provide a simple block diagram or schematic on how to set this up to explain a bit? thanks.
 

Re: PIC16F877A Question

If you don't know much about mains voltage stuff and you don't know how to build a voltage divider then you have a good chance of hurting or even killing yourself and at the very least setting teeny weeny parts on fire. Line level AC can kill you. Hit the books first, I can't imagine your instructor didn't warn you first.
Try experimenting with 6.3VAC (using a AC wall adapter) till you get a grasp of the concepts involved.
 

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