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Topic: Converting 220 AC to 5 DC (Read 2221 times) previous topic - next topic

amrit94

the output voltage of plug-mounted device is constant or varies with the voltage 220?

Grumpy_Mike

Quote
the output voltage of plug-mounted device is constant
Yes.

Quote
or varies with the voltage 220?
No.

All except old non regulated devices and they do not so much change output with the input voltage but with the current drawn. There devices are heavy because of the transformer. As long as the output says it it regulated then this is fine.

Boardburner2

#17
Nov 01, 2016, 04:14 am Last Edit: Nov 01, 2016, 04:28 am by Boardburner2
I found this device but do not know how to mount it


I had a GF like that once. :)

the output voltage of plug-mounted device is constant or varies with the voltage 220?
Thy have regulators normally so should give 5 V out whatever you plug them into.

UK 240 V nominal. US 110 V nominal input.

EDIT

USB outlet power supplies are 5V the world over, provided you get one for your area with a local plug it will do what you want safely.
A chinese supplied device may not.

amrit94

There is a commercial device that only makes the transformer and straighten without stabilize the voltage?

Boardburner2

Yes some of the cheap chinese supplies are advertised as regulated but some are not.
Another good reason to buy them locally.

amrit94

because I would need to measure the voltage with Arduino, so how can I do?

allanhurst

#21
Nov 03, 2016, 02:54 am Last Edit: Nov 03, 2016, 03:08 am by allanhurst
amrit94 - buy a cheap mains-in , 5v output device as suggested by many others above, and it will work and you'll be safe.

If you want to measure volts ( and make other useful measurements) buy a multimeter.

many arduino's have a usb socket which you use both for programming and monitoring and which also powers the arduino from the usb on the host computer.

It's only when programmed and you want to use it in a stand-alone application that you need a seperate psu.

regards

Allan

amrit94

hi
you know where I can buy a transformer with an output voltage proportional to the input?220  to 12

CrossRoads

All transformers have output proportional to the input, that's how they work.
Power In = Power Out (less some losses due to wiring).
So 120VAC, 5Amp In (600VA) = 12V, 50Amp out for example.

If you want AC to DC, that's a wallwart or an adapter supply like one of these:
220VAC to 5V DC
http://www.mpja.com/5-Volt-Adapter-Power-Supply-4A-Phihong/productinfo/30335+PS/
120VAC to 5V DC
http://www.mpja.com/5-Volt-DC-Plug-Power-Supply-4A-Regulated/productinfo/18520+PS/

Check the ratings of what you're buying and also the plug type for your country.

You can also get board-mountable AC/DC converters
http://www.digikey.com/product-search/en/power-supplies-board-mount/ac-dc-converters/4325929?k=recom&k=&pkeyword=recom&pv87=2&pv1525=62&FV=fff40042%2Cfff80229&mnonly=0&newproducts=0&ColumnSort=0&page=1&stock=1&quantity=0&ptm=0&fid=0&pageSize=25
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

amrit94

so, if the input varies then the output varies even it or remains constant at 5V?

CrossRoads

With the 5VDC output parts, the output stays at 5V, while the input can vary as noted:

100-240 VAC 50/60Hz
or
90-132 VAC 60Hz

This can happen because the input is converted to DC, chopped up into a square wave at very high speed, and filtered to become the DC output. If not much current is being drawn, the square may have low duty cycle (high vs low time) to keep the output filtered and level at 5V. If more current is being drawn, the duty cycle increases to keep the output at 5V. If more current is drawn than the circuit can supply, the output voltage may drop, or the output may be shut off to prevent damage from overcurrent until the current demand is decreased.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

amrit94

thanks
if I don't convert in dc,it is possible to obtain a voltage output that varies to vary the input?
if yes, where can I buy it?
Thanks a lot

Grumpy_Mike

Quote
if I don't convert in dc,it is possible to obtain a voltage output that varies to vary the input?
You are failing to understand. Even if you convert it to DC ALL transformers and UNREGULATING converters to DC change when the input changes. That is the way they work.

So ANY transformer will do that.

If you have a transformer that gives 5V out for 120V it must have a step down ratio of 5:120 or 1:24. So if you put 100V into it you get 4.166V out. If you put in 200V you get 8.33V out. If you put 5V into the 5V winding you get 120V out.

allanhurst

You're confusing the poor OP - so far as I understand he's very inexperienced and  just wants to power an arduino...

So while all this discussion is helpul and accurate  he'll need to learn a lot to interpret it...

see my post #21

regards

Allan

Boardburner2

I am wondering if what he needs is a 9 V supply to go in the power socket.

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