alternative to AC to AC power adapter

[ravi.2k17]

hi all,

I am going to build energy meter using Arduino with the help given in below link.
but I do not find any AC to AC (230 to 9v) adapter in my country. what could be alternative
to this? any circuit DIY circuit to make it my self?

How to build an Arduino energy monitor - measuring mains voltage and current — OpenEnergyMonitor 0.0.1 documentation

Different AC-AC Power Adapters — OpenEnergyMonitor 0.0.1 documentation

thanks

 

[KlausST]

Hi,

standard transformers will reduce AC voltage and maintain safety isolation.
even resistive voltage dividers may work .. but they are not "isolated". Only recommended if you know about safety regulations.

Klaus

 

[thannara123]

hi all,

I am going to build energy meter using Arduino with the help given in below link.
but I do not find any AC to AC (230 to 9v) adapter in my country. what could be alternative
to this? any circuit DIY circuit to make it my self?

How to build an Arduino energy monitor - measuring mains voltage and current — OpenEnergyMonitor 0.0.1 documentation

Different AC-AC Power Adapters — OpenEnergyMonitor 0.0.1 documentation

thanks

you can use 230 volt to 5 or 12 volt transformer .

or you can use one diffrential amplifire (take precuations its danger on live working)

 

[andre_luis]

I do not find any AC to AC (230 to 9v) adapter in my country

What the link refers to "power adapter" is a transformer, which carry no power at all, the use of unusual terminology leads to this type of misunderstanding. You could unwind any core in laminated silicon steel and roll with thin rigid wire in a 230: 9 ratio, for practical purposes, use as many turns as possible.

 

[ravi.2k17]

Hi,

standard transformers will reduce AC voltage and maintain safety isolation.
even resistive voltage dividers may work .. but they are not "isolated". Only recommended if you know about safety regulations.

Klaus

now i understand, i can use any transformer of 6-0-6 or 9-0-9 or 12-0-12 rating. what should be the current rating in the transformer? i know in primary winding I will have 100 amp flowing...what about in secondary winding ? so that it should be safe for me as well as my Arduino.

--- Updated Dec 23, 2020 ---

What the link refers to "power adapter" is a transformer, which carry no power at all, the use of unusual terminology leads to this type of misunderstanding. You could unwind any core in laminated silicon steel and roll with thin rigid wire in a 230: 9 ratio, for practical purposes, use as many turns as possible.

now i understand, i can use any transformer of 6-0-6 or 9-0-9 or 12-0-12 rating. what should be the current rating in the transformer? i know in primary winding I will have 100 amp flowing...what about in secondary winding ? so that it should be safe for me as well as my Arduino.

--- Updated Dec 23, 2020 ---

you can use 230 volt to 5 or 12 volt transformer .

or you can use one diffrential amplifire (take precuations its danger on live working)

now i understand, i can use any transformer of 6-0-6 or 9-0-9 or 12-0-12 rating. what should be the current rating in the transformer? i know in primary winding I will have 100 amp flowing...what about in secondary winding ? so that it should be safe for me as well as my Arduino.

 

[andre_luis]

now i understand, i can use any transformer of 6-0-6 or 9-0-9 or 12-0-12 rating. what should be the current rating in the transformer? i know in primary winding I will have 100 amp flowing...what about in secondary winding ?

No, I just meant that in the lack of the transformer which is not available in your country - as you said - you can unwrap any laminated silicon steel tranformer and wind it by yourself according to your specs. Since the current requirement is too small, you will not concern with the size of the transformer, and just to release you from magnetic core calculations, be sure that by using standard capped wires, you can roll any amount of turns, obviously taking into account the spiral ratio mentioned above.

 

[betwixt]

know in primary winding I will have 100 amp flowing

You are confusing the power adapter transformer and the current sensing transformer. The 9V is from the adapter, the 100 Amps flows through the other transformer!

If 100A flowed through the adapter transformer primary the Arduino would be dissipating 230KW!!!. Looking at it the other way around, the 9V would be capable of supplying 2,556 Amps and need an output cable with two 100mm diameter wires in it!

Brian.

 

[ravi.2k17]

You are confusing the power adapter transformer and the current sensing transformer. The 9V is from the adapter, the 100 Amps flows through the other transformer!

If 100A flowed through the adapter transformer primary the Arduino would be dissipating 230KW!!!. Looking at it the other way around, the 9V would be capable of supplying 2,556 Amps and need an output cable with two 100mm diameter wires in it!

Brian.

i understand there are two transformers here.
1) current sensing transformer : CT sensor . I am not taking about this.
2) power adapter transformer : this is what i am talking about. it can be 9-0-9 (9V rms output value as per the doc as only 5v can be tolerated by Arduino) . what should be transformer's secondary current to be on safe side? to calculate mains voltage its primary winding will be connected to main line which has generally 100 A current rating.

 

[betwixt]

The 100A rating is irrelevant, the actual current will be (approximately) what the Arduino circuits draws multiplied by 9/230.
The Arduino probably uses around 25mA but there are many Arduino designs and they all differ slightly. Add to that the current flowing through its input/output pins and the current used by any other circuitry. You will certainly need to target around 7.5V or a little higher then use a 5V regulator to drop it to a stable 5V.

If I had to guess at the transformer rating you need - 230V in, 7.5-0-7.5 out, 10VA rating but without seeing the full design I stress that is only a guess.

Brian.

 

[RCinFLA]

Your best scrounging bet is a mobile phone charger that has 5VDC output for running Arduino.