Discussion in "PIC Microcontroller Discussion" started by    Karan123    Jun 15, 2015.
Mon Jun 15 2015, 09:11 AM
Hi forum,

I want to make low cost AC Volt-meter 0 - 1000 V AC with MCU Like PIC16F72.

How do I fed AC Voltage to MCU Analog Pin ?

1) With Voltage divider circuit
2) First Convert AC into DC then fed in to Analog PIN

any other suggestion are welcome ..

Wed Jun 17 2015, 01:34 AM
Obviously with voltages around 1000v you need to be careful.
None of the circuit will be safe to touch unless you use a transformer
to step down the signal.

Basically you just need a resistor divider network.
You could measure AC by sampling just the positive half of the cycle and
calculating the R.M.S voltage.

Wed Jun 17 2015, 08:11 AM

I want to use only resistor divider network

How do i measure AC by sampling in 'C'?
Fri Jun 19 2015, 04:23 AM
I would not recommend using a voltage divider or something like that for measurement of AC that too @1000V. You better go for a Metering IC from Analog devices or similar to do all these measurements. Check the following link:
Tue Jun 23 2015, 05:18 PM

How do i measure AC by sampling in 'C'?


Add a diode to your circuit to shunt the negative half of the
signal to ground.

Exactly how to read the value depends on the compiler you use.
Some will have a built in routine for example readADC();
What compiler do you have ?

Assuming you are measuring mains type sine waves
you need to find the peak voltage.

Sample the signal over a few cycles.
Note the highest reading per cycle.
Discount any very high or very low readings.
Average the rest.
Multiply by 0.707 to get the RMS voltage.

[ Edited Tue Jun 23 2015, 05:21 PM ]
Thu Jul 02 2015, 09:12 AM

i will not prefer costly ic because of product cost is low.


I am not getting you.

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