How To Draw 5V 100mA from 3-phase without transformer?

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Sobakava

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I want to get 5V 100mA DC from 3-phase 380V mains without using transformers. I tried capacitor-resistance in series and 3phase bridge but can't draw so much current.

I'm trying to get power for my board without using transformers to keep it low cost, I do not need galvanic isolation for this board.

Could you advise me a schematic to try?

Regards
 

Is it STAR or DELTA configuration .. or in another words, is the NEUTRAL available?
Regards,
IanP
 

yes I've neutral also.
 

In ths case I would select only 1 phase and neutral, and use the attached circuit with the following changes:
FS - 250mA
FR = 0
R1 = 10Ω
C1 = 3µF
ZD1, ZD2 = 8.2V
C2 = 470µF
ZD3 = 5.1V/5W
Regards,
IanP
 

I need to use all 3 phases because, I want that circuit will continue to work even if 1 or 2 phases from main supply becomes cutted.
 

Take a look at the attached circuit ..
It takes power from all 3 phases ..
The 5.1 zener diode should be at least 5W ..
Regards,
IanP
 

how much current can I expect from this circuit?
 

I would say >150mA ..
Regards,
IanP
 

    Sobakava

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I suppose that circuit for 3 phase 5 V wont work . Once capasitors charged then wont transfer charge in forward direction through diode .
And also that circuit on picture is not optimized

2 Sobakava . Take a look to converter alike solution (let say chargers for ericsson mobiles ) . They are littel bit more complicated than what you are trying to do .
 

    Sobakava

    Points: 2
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