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AC RMS voltage line connection with ADC

What schematic will be the best way to convert the AC Analog voltage line 110v (RMS) to be converted in Digital voltage ranging between 0 to 10 V  and is it possible to adjust the brightness LED 

your intel on this will be very helpful

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*** Danger Will Robinson ***


There are plenty of COTS that already turn standard line power into DC - SAFELY.  I would tend to go with those if you do not have any experience in doing this type of thing as it could injure or kill you if your design is not properly designed and not fully shielded.

MY $0.02


That said, use a half or full-wave rectification feeding a PWM circuit or voltage regulator depending on power requirements to achieve your 10VDC.  The illumination of the LED is based upon current provide to the LED.  Another warning, too much voltage to the LED can destroy its junction and render it useless.

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@Minions wrote:

The illumination of the LED is based upon current provide to the LED.

Another way is to use a pulsed current.  The duty cycle of your current will affect the visibility.  There are chips that will do this for you. We used one the talked over I2C and it controlled 8 LEDs.

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Can you please specify the chip which will be very useful for my project? What will be the other parameters I have to take care of so that my circuit should not blow up   

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IF you are having to ask questions like this, then please stay away from the mains unless you.

Get your design and wiring checked by someone certified to do so before connecting.


Some further points:

What are you trying to do?

What voltage range do you want to measure? You do know that nominal 110 V can vary quite a lot, and have spikes on top of that?

What frequency do you need to capture? Are you trying to resolve short spikes?

You have asked a fairly straightforward mains to DAQ question. What does the brightness of an LED have to do with anything?

Frankly this smack of college homework to me.


Fault Level: You must have fuses as close to the instrumentation pick-off point as possible. That way, if there is a fault in your wiring the instrumentation fuse pops, and you do not have the full mains fault current flowing through your instrumentation wiring.


I would use isolation amplifiers on the voltage inputs. That way you can use a simple potential divider on the input to scale to the voltage you want, but make sure that the isolation amplifier has a suitable frequency range.


So it would go something like:


Line voltage->Fuse(or other protection device)->Potential divider->Isolation Amplifier->DAQ module.



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