230V AC -> 5V DC (60-100mA) ???

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#1
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Hi everybody!

I have a PCB with very small dimensions!
So I have no space for the conventional way with trafo,
rectifier bridge,...

So do anybody have ideas or know any parts which meets my
requirements?

best regards

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Uuuh, well i think it's not a matter of the parts (which basically consist of a capacitor and a resistor plus a zener), but the mere fact that you're asking this question. I mean, you're dealing with highly dangerous voltage levels. I would not give you any ready-to-use advise via an online forum on such a subject. I mean, either you know how to deal with 230 volts and don't need basic advice on how to calculate the rc circuit, or it's too dangerous for you to get simple advise and just jump on it..

Sorry, but that's my cautious opinion on that..

-- Thilo

Einstein was right: "Two things are unlimited: the universe and the human stupidity. But i'm not quite sure about the former..."

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Rhom BP5040
Alexander

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OK If you think only for place, a condensator + resistor +++ will take same place than transformator if you need 100mA.
If you use a bridge you must count 1uF -> 60mA ( 30mA if juste 0ne diode).
Condensator must be X2 (275Vac) type and have a resistor serie to reduce the start current.
I use this power with 2x1uF and a coil serie 820uH to make +-12V dc.
Becare full It is hurt if you have your finger on the board!
Thierry

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AC-dc example

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Ehmmm i know these are from the "enemy" :oops: :oops:
But they do make some damm good AppNotes ..... :roll: :roll:

Pracis
http://ww1.microchip.com/downloa...

Theory (Best one ) ..
http://ww1.microchip.com/downloa...

Another , with calculations at last link
http://www.zen22142.zen.co.uk/Ci...
http://uk.geocities.com/ronj_121...

/Bingo

Last Edited: Fri. May 20, 2005 - 05:51 PM
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@Zauberer

Do you have a better example (better quality) of the above one ??

/Bingo

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Schematic from Motorola pdf.
PCB from PS1.pdf(in russian)
Alexander

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Supertex specializes in high voltage ICs. This one will probably do what you need with hardly any external components:
http://www.supertex.com/pdf/datasheets/SR03.pdf
Cruise their site, they have others like this.

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Will this one work ??

http://www.discovercircuits.com/...

I what's the approx voltage across the 220pf ??

Is the 220K - 10K a 1:22 voltage divider , dividing the approx 400v (220v mains) ??

/Bingo

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That little board looks like it would not meet clearance requirements
for 240 vac unless perhaps it is intended to be encapsulated.

Tom Pappano
Tulsa, Oklahoma

Tom Pappano
Tulsa, Oklahoma

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@Bingo: the transistor (2222) is a crude zero-crossing detector and will mostly be turned on during periods of high voltage, so the 220pF will only have to withstand about 5% (10k/230k) of the mains peak. However, if the 2N2222 should fail open circuit, the capacitor will see the full peak voltage of 400V and may be damaged. This will be the least of the problems, as at about the same time the MOSFET will melt, the 470uF capacitor will explode and 400V will be applied to the logic circuit.

I think what I'm trying to say is, I wouldn't use this circuit.

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Why bother with on board AC-DC?
Just use a wall wart.
It is safe, legal, cheap, easy, and saves alot of board space.
It also makes it very easy to adapt your device to both 230V and 110V power systems.

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Could you possibly use mobile phone charger? You could even dissect it and use the electronics only. My wife's charger for Siemens A57 gives 5V/400mA and it's really small. The chargers costs usually a buck or two on eBay...

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wow, so many posts...

I'm suprised! :-)

First of all, I'm not a newbie, but I'm not really an expert for this
analog stuff! But I think I'm getting better ... :? @ DO1THL

Damn, this M*******p application notes are really good!
COME ON ATMEL, HAVE A LOOK AT IT ! ! ! !

I'm just looking at this SR036 chip! It looks not bad, but after
calculating it will give me 50mA at maximum without any heat-
precautions.

External power supplies are definetly not possible!

I think I will use the microchip suggestion!

Thanks to all!

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Dor

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be very careful with the supertex off line parts
ALL my samples blew up violently over a period of a few weeks
I bailed and tried a cap in line - but that did not work well as the current changed a lot.
finally settled on a standard transformer etc...

There are other "off line" regulators out there - do a google search

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Re:230V AC -> 5V DC (60-100mA) ???
I need similar requirement by using simple/low-cost parts. Any good ideas are welcome. Thanks in advance.

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Ross McKenzie ValuSoft Melbourne Australia

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Well, have you thought of ... salvaged USB hubs (up to 500 mA; if your hub is really broken, you can open it and I found a working 3.3 v LD regulator, for its internal controller + the main power supply, which is 5 v...)

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I would have thought this belongs to General Electronics!

the OP wrote:

Quote:
External power supplies are definetly not possible!

Can you explain that in a bit more detail!
Bearing in mind that in any case you will have a lead that plugs into the mains and connected into your equipment, why not use one of the very small AC-5VDC USB power supply cubes, which are no larger than a mains plug & use USB cable.
Low cost, universal, no need for compliance testing, easy to service/replace, etc. I don't quite understand the hard & fast rule of "can't do it" ???

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Charles Darwin, Lord Kelvin & Murphy are always lurking about!
Lee -.-
Riddle me this...How did the serpent move around before the fall?

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I always have a bunch of USB phone chargers (€ 3) around. When I need 230V->5V up to 1 A, I just take one of those. If necessary, I remove the plastic and voilá, there is my power supply. Apply shrinking tube to taste.

If this is not a one-off, a look at the devices from Traco power might be a good idea. They make small 230V switching supplies.

I tend to post off-topic replies when I've noticed some interesting detail.
Feel free to stop me.

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buffi wrote:
I always have a bunch of USB phone chargers (€ 3) around. When I need 230V->5V up to 1 A, I just take one of those. If necessary, I remove the plastic and voilá, there is my power supply. Apply shrinking tube to taste.

If this is not a one-off, a look at the devices from Traco power might be a good idea. They make small 230V switching supplies.

Careful!

http://www.righto.com/2012/03/in...

Ross McKenzie ValuSoft Melbourne Australia

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The chargers i have here are branded and at least show certification signs (though i don't know if they were actually tested).

I tend to post off-topic replies when I've noticed some interesting detail.
Feel free to stop me.

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If I remember correctly, David Jones in one of his EEVBlog shows examined two such devices, both branded with all manner of certifications, and found them both to be "accidents waiting to happen".

Ross McKenzie ValuSoft Melbourne Australia

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I take your point Ross. I have not looked inside the power supplies that I have(as it tends to stuff them.) I have looked inside a lot of CCFL light globes though (sometimes called long life light globes, but I find they have fairly short lives).
If the power supplies are as bad assome CCFL's, yes I guess there may well be potential problems.

Charles Darwin, Lord Kelvin & Murphy are always lurking about!
Lee -.-
Riddle me this...How did the serpent move around before the fall?

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Here is Dave's "teardown" episode.

http://www.eevblog.com/2012/11/2...

Ross McKenzie ValuSoft Melbourne Australia