How this power supply work?

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#1
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Hi
This power supply is 3w and its small in size.
I want to build something like this.
Size matter to me
What topology should I use for such small power supply?

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It's most likely a flyback converter.

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Kartman wrote:
It's most likely a flyback converter.

from phase it going to diode half rectifier first then to rest of circuit

maybe i should reverse engineer it

 

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Maybe you should. There's not many components. The secret is in the design of the transformer.

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Kartman wrote:
Maybe you should. There's not many components. The secret is in the design of the transformer.

its looks like this 

first i should test it in ltspice

 

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How does it work? Nicely.

The largest known prime number: 282589933-1

Without adult supervision.

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It's most likely a flyback converter.

 

Yes, but it could also just be a simple stepdown transformer and a linear regulator, (e.g. 7805).

 

What does the 3-lead device that looks like a transistor say on it?

 

When you talk about power supplies it would be helpful to know, at a minimum:

Vin

Vout

current requirement

 

Other factors can come into play but those are the main ones.

 

JC

 

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Doc, the core is not big enough for 3W at 110VAC/60Hz. Being ferrite, even more so.

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From the size of it, it's definitely switching.

The largest known prime number: 282589933-1

Without adult supervision.

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navidrct wrote:

its looks like this 

 

I don't think it does. There is a huge disparity in the number of components.

#1 This forum helps those that help themselves

#2 All grounds are not created equal

#3 How have you proved that your chip is running at xxMHz?

#4 "If you think you need floating point to solve the problem then you don't understand the problem. If you really do need floating point then you have a problem you do not understand." - Heater's ex-boss

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The case in the picture clearly states 220/240 ac, I would assume 50hz.

 

 

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Looks like a flyback with weak regulation.

Power Integrations offers  nice suite for supply design. PI chips have nice protection features. IMHO easier and safer than discrete based solution. Used in a number of appliances built -ins  and instruments.