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KT4YE
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Join Date: Jan 2011
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Wall Warts

02/28/2012 3:38 PM

A typical wall-mounted low-voltage plug-in power supply consists of a power transformer, a (bridge?) rectifier and (perhaps) some filtering. Simple.

Recently I've seen some wall mounted Power Supplies that are physically light. They can't possibly contain a typical iron-core power transformer, but they output low-voltage to power things like cell phones.

I was going to take one apart and figure it out, but my wife caught me and threatened abuse and cold showers if I opened it up.

What's inside?
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Pathfinder Tags: power supplies wall warts
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redfred
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#1

Re: Wall Warts

02/28/2012 3:52 PM

Usually a very efficient, high frequency transformer coupled, buck type switching supply. The transformer can be so small you'll mistake it for a filter inductor. The switching supply controller is frequently found inside an encapsulated drop on the circuit board and a power MOSFET transistor, Schottky diode and small filter capacitor complete the minimum parts list.

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lyn
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#2

Re: Wall Warts

02/28/2012 4:04 PM

It's better that you don't know.
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Doorman
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#3

Re: Wall Warts

02/28/2012 4:25 PM

Tsk tsk tsk.

Afraid of the wife.

Was Edison afraid of the missus? Edwin Land used the kitchen sink, totally disregarding the threats of cold showers.

Come on man! Get out the tool kit and get to work!

Go down to the second-hand store and get one for a quarter. No sense pissin her off.

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Usbport
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#4
In reply to #3

Re: Wall Warts

02/28/2012 4:35 PM

I gave you a Good Answer, but only because there isn't a button for 'Damn Good Answer'.

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KT4YE
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#6
In reply to #4

Re: Wall Warts

02/28/2012 4:47 PM

You have obviously never met my wife!

TANSTAAFL -- Robert Heinlein
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Mikerho
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#7
In reply to #3

Re: Wall Warts

02/28/2012 11:52 PM

Wow, she looks nice! Why is she shaking her head though? I don't understand. Can she not hear me? I thought I made sense!

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#5

Re: Wall Warts

02/28/2012 4:44 PM

Afraid of Wal warts? What about the inventor of gun cotton, story has it, he cleaned up a nitric acid (I think) spill with the wife's apron. Rinsed it out and thought everything was A OK. Boy was he wrong, wifey went to pull the cake or whatever out of the wood stove and voila, gun cotton was discovered. Imagine he's still running.
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ffej
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#8

Re: Wall Warts

02/29/2012 12:48 AM

I'm not afraid of my wife! It's just sometimes better if I don't tell her everything.

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Wal
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#9

Re: Wall Warts

02/29/2012 2:18 AM

They are full of smoke.

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Captain Curious
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#13
In reply to #9

Re: Wall Warts

02/29/2012 2:13 PM

And mirrors

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snatr
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#10

Re: Wall Warts

02/29/2012 11:20 AM

This just came up the other day in another thread. Here's a link that might help.
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WJMFIRE
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#11

Re: Wall Warts

02/29/2012 1:19 PM

This is a 6 Amp switching power supply.

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Andy Germany
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#12

Re: Wall Warts

02/29/2012 1:38 PM

What you are wondering about is a "Switched Mode Power Supply". They are more reliable, more efficient and waste less energy. So they are usually quite cold, even when running at their max output.

I first used them sometime in the late 70's as far as I remember, tiny (for then) boxes (about the size of a house brick) supplying 200 amps at 5 volts...

You can read about them here:-

http://en.wikipedia.org/wiki/Switched_mode_power_supply

Today, the chips are better and they are composed of less components, but the ones there are, are far more intelligent.

I use nothing else......

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cuba_pete
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#14

Re: Wall Warts

03/02/2012 11:32 AM

Vampires! One and All!

Give me a good 'ole linear power supply any day. Damned SMPS's are too noisy for me...all them no good harmonics messin' up my analog data!
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Users who posted comments:

Andy Germany (1); Captain Curious (1); cuba_pete (1); Doorman (1); ffej (1); JWthetech (1); KT4YE (1); lyn (1); Mikerho (1); redfred (1); snatr (1); Usbport (1); Wal (1); WJMFIRE (1)

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