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Efficient method to conv. 230V AC to 30V AC only 5-10mA

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Efficient method to conv. 230V AC to 30V AC only 5-10mA

Postby raxon » Sat Aug 25, 2018 12:58 pm

Efficient method for converting 230V AC (Germany) to 30V AC with only 5-10mA needed?

Hello, :)

so far I use the good old "capacitor + resistor divider" method. It is easy to calculate that this mainly generates loss.
Therefore, I thought about winding my own transformer (first coil 3-4 turns, second 800+).
Before I go for that folly, I wanted to ask whether there might not be a better (integrated) solution. Is there any building block that could help me here?

Thanks for your help!
raxon
 
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Re: Efficient method to conv. 230V AC to 30V AC only 5-10mA

Postby SteveMJ » Wed Aug 29, 2018 11:38 am

I think that you will find the integrated solution is a transformer...

There are methods that you allude to using resistor and capacitors. IIRC Microchip had some good application notes for this.

Regards, Stephen
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Re: Efficient method to conv. 230V AC to 30V AC only 5-10mA

Postby raxon » Wed Aug 29, 2018 1:27 pm

SteveMJ wrote:I think that you will find the integrated solution is a transformer...

There are methods that you allude to using resistor and capacitors. IIRC Microchip had some good application notes for this.


In this case, the voltage divider would piss about 87% down the drain. Are there no helpful integrated circuits as of yet?
raxon
 
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Re: Efficient method to conv. 230V AC to 30V AC only 5-10mA

Postby SteveMJ » Wed Sep 26, 2018 5:35 pm

raxon wrote:
SteveMJ wrote:I think that you will find the integrated solution is a transformer...

There are methods that you allude to using resistor and capacitors. IIRC Microchip had some good application notes for this.


In this case, the voltage divider would piss about 87% down the drain. Are there no helpful integrated circuits as of yet?


A transformer sounds like the answer then.

When you meant an integrated solution, did you mean integrated circuit? Any semiconductor device would require some form of energy store//transfer.
SteveMJ
 
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Re: Efficient method to conv. 230V AC to 30V AC only 5-10mA

Postby raxon » Thu Sep 27, 2018 9:38 am

When you meant an integrated solution, did you mean integrated circuit? Any semiconductor device would require some form of energy store//transfer.

I meant the combination of an integrated circuit and some additional "gadgets", such as capacitor(s) and resistances. In short, a circuit which "reprocesses" at least some of the - otherwise lost - 87% (in this case).
With a transformer (current solution, inflexible and bulky) I am likely losing 40-75% in this scenario as well.
raxon
 
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Re: Efficient method to conv. 230V AC to 30V AC only 5-10mA

Postby nophead » Wed Jan 02, 2019 12:34 pm

A capacitive dropper doesn't waste any energy, it doesn't get hot like a resistor. In practice practice you add a series resistor to limit inrush current and perhaps some form of shunt regulation if the load is not a constant current, so those would waste some.
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