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Convert High Voltage AC Signal into Low Voltage DC Signal

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electrousa

New Member
I need to design a circuit which converts 220V AC signals into 3.3V DC signals.

The 220V AC signals are part of elevator system which is used to detect every single elevator's status and report to a central control unit or something like that.

The 3.3V DC signals are to an embedded micro controller which is on my board.

What I need to do is to find a circuit which converts the 220V AC signals into 3.3V DC signals and finally can be interfaced to my micro controller.

I have no knowledge on the elevator system so if anyone have advices on how to converts 220V AC signals specially in elevator system to 3.3V DC signals, that will be great appreciated.

Any general knowledge on how to convert high voltage AC signals to low voltage DC signals are also great!

Thanks in advance.
 

ronv

Well-Known Member
Most Helpful Member
Maybe a little more info would help.

Are you trying to detect the presents or absents of 220 volts by converting it to a 3.3 volt dc signal.

Or are you building a power supply to convert 220 to 3.3 vdc.
 

crutschow

Well-Known Member
Most Helpful Member
The easiest and safest way is to use a small transformer. 220V to 2.5V AC would be good but 6.3V AC outputs are likely more common. Just rectify the AC with a diode and capacitor filter, and then reduce that to 3.3V DC with a series resistor and a 3.3V zener diode to ground.
 

electrousa

New Member
The reason I need to convert it to a 3.3 volt dc signal is trying to detect what information is carried through the 220 circuit inside the elevator system. I have no knowledge on elevator system...
If somebody can describe something about the 220 volt ac interface(like how many wires and how it works etc.) for the elevator system that will be great!
 

alec_t

Well-Known Member
Most Helpful Member
I have no knowledge on elevator system...
In that case how will you be able to interpret any information you detect? Why do you think there is information (as distinct from just power) in the 220VAC?
 

electrousa

New Member
You are right from this point, It maybe just a 220V AC power. but the control unit need to judge the status of the elevator through this 200V AC ring.
 

electrousa

New Member
Thanks for the information, I think it is a good idea to using opto-isolator convert the AC to DC easily.

Any suggests on the part selection and circuit design will be greatly appreciate!
 

crutschow

Well-Known Member
Most Helpful Member
But we still don't know the nature of the signal you are trying to detect. :confused:
 

KeepItSimpleStupid

Well-Known Member
Most Helpful Member
OK, I'm assuming that you need to know the presence or abcence of voltage. Industrially this is done using I/O modules. They could be mounted on a backplane or separate units. They require a logic suplly of 5, 15 or 24 V.

Here is just one link: http://www.crydom.com/en/Products/C...xt1=Digital I/O Modules&SBCatPage=&FromPage=1

Here is another such system: http://www.advantech.eu/products/ADAM-3864/mod_F4797E46-CC0B-46E4-855D-0EF5053AAFF4.aspx

The modules are sometimes universal and available from many manufactures.

There are also quad modules availabe.

What we don't know is:
1. Are you interested in the presence/abcence of 240 VAC?
2. Is everything in one place?
3) How many points and locations?

You may have to provide interfcing from 5V logic to 3.3 V logic.
 

alec_t

Well-Known Member
Most Helpful Member
If all you're wanting is to detect the presence or absence of 220V then an opto-coupler and resistor are about all you need. Or you could use a mains neon indicator and a photo-sensor (e.g. LDR).
 

KeepItSimpleStupid

Well-Known Member
Most Helpful Member
Right, but this is a commercial establishment and not a simple experiment. The interface should not be home brew. It should be approved by a regulatory agency.
 
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