To step down ac voltage

[AMSA84]

rfredel,

That transformeless way that you suggest doesn't fit to Electro Builder needs, right? He wants an AC voltage source and not DC. The transformeless suggestion supplies only DC, right?

 

[tpetar]

No, transformeless supply in first section lower voltage with resistor and capacitor in parallel and with one resistor in serie for surge current, after that you have AC voltage. DC if you need you will get using gretz and rest parts.

 

[AMSA84]

Well, but in the application note, they have a scope image and it seems to be DC. (?)

 

[tpetar]

Well, but in the application note, they have a scope image and it seems to be DC. (?)

Change scope for sure.

Resistor and capacitor cant rectify AC.

 

[rfredel]

Hello AMSA84,

I've bought this transformer a few month ago. Here is **broken link removed** or **broken link removed**.

Your asking about a transformer with a power of 10kVA. This is highpower and for professional use. Here you can only use professionel transformers and we are talking about consumer transformers with a max. power of 3kW.

I can look for a price of this professional transformer but it will not be cheap.

Regards

Rainer

 

[AMSA84]

Very good! Nice indeed.

How much was the shipping cost to germany?

 

[rfredel]

Hello AMSA84,

the shipping cost were very high, because I need it very quickly and with US certification. I believe it was US$ 50,00. It was for a customer of me.

Normaly I look for cheaper shipping cost and if I can get it in Europe about not paying import tax.

Regards

Rainer

 

[rohitkhanna]

hi frnds i was new to this forum...i want to construct a basic ac stepdown voltage circuit with out using transformers...is any body aware of this pls reply me along with the circuit

For your purpose, i STRONGLY recommend that you invest in a step-down transformer for 220 to 110 Vac.
Trust me, all the other "clever" solutions have too many limitations. Only a transformer will do the job you require, and it will be worth it.

 

[tpetar]

Hello AMSA84,

the shipping cost were very high, because I need it very quickly and with US certification. I believe it was US$ 50,00. It was for a customer of me.

Normaly I look for cheaper shipping cost and if I can get it in Europe about not paying import tax.

Regards

Rainer

Thats to much. For that money you can buy some device and extract nice real trafo from it, such battery chargers or something else. Better buy parts what you have in your country, you avoid importing taxes, and high shipping prices. Ebay site and such sites are nice but when you add all taxes and parts costs... In my country in customs they have special lunatics for workers, and there is lots of problems for anything.

 

[AMSA84]

I am sorry for the noob question, but what is "strafo"?

 

[tpetar]

Trafo = Transformer

 

[rfredel]

Hello tpetar,

I know that the shipping costs was very high. But look what I wrote: "I need it very quickly and the US certification." This certification I can not get here in Germany.

Normaly I order my transformers at my friend. He has a firm for making transformers.

Regards

Rainer

 

[tpetar]

What do you mean under US certification?

There is no certification in US which cant be done in Europe.

 

[rfredel]

Hello,

There is no certification in US which cant be done in Europe.

yes, that's right, but my customer (US Embassy) want a US certification.

So I do it.

Regards

Rainer

 

[tpetar]

Oh, ok then. Then must be just like uncle Sam says.

 

[D.A.(Tony)Stewart]

Q AC Power Conversion for personal use without transformer. Need help to build 1A 120V from 240V ?

A The choices are clearly in favour of auto-transformers, but you need to be clear on your priorities and communicate that.

Things to consider; budget to buy, investment time to learn, time to finish, learning skills and capability, safety risks, failure risks, load compatibility, noise compatability, size limit, weight limit, portability, heat loss.

If you specified how important these factors, anyone could choose for you. If you can't , you will have a hard time trying to decide.
All the choices of inverters for AC,DC and transformers come down to cost.

I have guessed what I think I can find in prices, your mileage may vary.

Cheapest: Autotransformers in any power rating.
- $5$~$50/kW used to new for 10kW
Safest: isolation transformer, but also heaviest and much more expensive.
- $50~$500/KW used to new
Lightest: SMPS inverters but most expensive.
- $150~$1000/kW

https://www.ebay.com/sch/i.html?_sacat=0&_nkw=autotransformer&_nkwusc=autortansformer&_rdc=1

 

[AMSA84]

I definitely would go to a conventional transformer.

@tpetar:

I'm sorry to bother you again about the application note, but if Electro Builder is looking for a 120VAC why this application note was suggested? Since it's output is VDC?

Regards

 

[tpetar]

I definitely would go to a conventional transformer.

@tpetar:

I'm sorry to bother you again about the application note, but if Electro Builder is looking for a 120VAC why this application note was suggested? Since it's output is VDC?

Regards

I explain earlier, you just need to read posts. Post #22.

You should try to understand circuit, and how it works.

If Electro Builder whant transformeless, then should be transformeless. ;-)

 

[tpetar]

In my post #7 I mention triac based solution for this, with this way you can have higher currents.



The schematic in Figure 10 shows a step-down circuit used to approximately divide by two the rms voltage between the line input and the inductive load (L1). C2 and R3 provide a turn-on delay of approximately 7 ms.

The diode bridge, with diodes D1 and D2 and R2 resistor are used to discharge C2 at each line zero voltage. This resets the voltage charge at each new half line cycle, and keeps the same turn-on delay. The Transil reduces the power dissipation through R3.



Also see this similar :

https://kakopa.com/PSA220-110/index.html

 

[D.A.(Tony)Stewart]

if you wanted to convert AC to DC off the power line you can use any "OFFLINE regulator" for low power only in transformerless
Then convert DC to AC with an inverter design to create a AC-AC step down using SMPS "OFFLINE REGULATOR"


But this is very costly and prohibitive with plastic caps at large currents which becomes more expensive than variacs or autotransformers in the 1 AMP range at 350Vac rating. also efficiency losses become significant heat sources for IC and HIPOT tests prohibit reliable operating at 1500V test.

Hence the commercial solutions are < 1Watt.

Examples of TI OFFLINE AC-DC converters
https://www.onsemi.com/PowerSolutions/parametrics.do?id=449