Output 4 to 22 volts.

[micky]

I've gotten used to the idea that power bricks and other things can
accept 110 to 240 input volts and still put out the same output
voltage. Xener diodes, iirc, and all that.

But lately I've been seeing wall warts and power supplies that not
only have variable input, they say they have variable OUTPUT. I saw
a little wallwart at Best Buy, for 10 or 15 dollars that said this,
(4.5 or 6 volts to 12 volts**) , and now I notice that my Targus
car/plane laptop power supply (which I've never actually used, except
one 3 minute test) says it puts out 4 to 22 volts DC.

How does it know which to do? When? And how does it do it?

How does the wallwart keep from overcharging with 12 volts a device
that needs only 6 volts?

Thanks.


Ths also relates to my question in the next thread, which I hope to
post later tonight.

 

[William Sommerwerck]

Variable-output power supplies have been around for many years.

The voltage is selected with a switch -- the supply doesn't "know" what
voltage is needed.

I've never seen one with continuously variable output.

 

[Phil Allison]

"micky"

I've gotten used to the idea that power bricks and other things can
accept 110 to 240 input volts and still put out the same output
voltage. Xener diodes, iirc, and all that.

** Such unit are SMPS = Switch Mode Power Supplies.

But lately I've been seeing wall warts and power supplies that not
only have variable input, they say they have variable OUTPUT. I saw
a little wallwart at Best Buy, for 10 or 15 dollars that said this,
(4.5 or 6 volts to 12 volts**) , and now I notice that my Targus
car/plane laptop power supply (which I've never actually used, except
one 3 minute test) says it puts out 4 to 22 volts DC.

How does it know which to do?

** It doesn't know.

YOU have to know and set the adjustments appropriately.

Makes them a real hazard to use.

How does the wallwart keep from overcharging with 12 volts a device
that needs only 6 volts?

** SMPS are not battery chargers.


..... Phil

 

[William Sommerwerck]

How does the wall wart keep from overcharging
with 12 volts a device that needs only 6 volts?

** SMPS are not battery chargers.

They are if the device is charged from its AC adapter.

I have a number of SMPS chargers, for cell phones, juke boxes, camera
batteries, etc.

 

[Phil Allison]

"William Sommerwanker = TROLL "

How does the wall wart keep from overcharging
with 12 volts a device that needs only 6 volts?

** SMPS are not battery chargers.

They are if the device is charged from its AC adapter.

** A * Power Supply * is not a battery charger.

I have a number of SMPS chargers,

** No.

You have a number of SM battery chargers.

Wanker.


.... Phil

 

[Jamie]

William Sommerwerck wrote:

How does the wall wart keep from overcharging
with 12 volts a device that needs only 6 volts?


** SMPS are not battery chargers.

They are if the device is charged from its AC adapter.

I have a number of SMPS chargers, for cell phones, juke boxes, camera
batteries, etc.

But, there is no supervisor circuitry in them, the power supply, which
is what you have only supplies the raw power needed for both the device
and the charging circuit inside the device.

You and I may get some flake over that one

Jamie

 

[William Sommerwerck]

A battery charger is a specialized type of power supply. It is intended to
deliver "power" to rechargeable batteries.

 

[Phil Allison]

"William Sommerwanker"

A battery charger is a specialized type of power supply.

** Massive red herring and straw man fallacy.

Plus a blatant context shift.

Wot a desperate wanker.

 

On Sat, 16 Mar 2013 17:30:43 -0400, micky <NONONOmisc07@bigfoot.com>
wrote:

I've gotten used to the idea that power bricks and other things can
accept 110 to 240 input volts and still put out the same output
voltage. Xener diodes, iirc, and all that.

But lately I've been seeing wall warts and power supplies that not
only have variable input, they say they have variable OUTPUT. I saw
a little wallwart at Best Buy, for 10 or 15 dollars that said this,
(4.5 or 6 volts to 12 volts**) , and now I notice that my Targus
car/plane laptop power supply (which I've never actually used, except
one 3 minute test) says it puts out 4 to 22 volts DC.

How does it know which to do? When? And how does it do it?

How does the wallwart keep from overcharging with 12 volts a device
that needs only 6 volts?

Thanks.


Ths also relates to my question in the next thread, which I hope to
post later tonight.
I have several universal ones here from Kensington. They made them in

70 watt and 115 watt versions. The 115 watt one has input cords for
120VAC, 12VDC (car lighter adaper), and a rather funky round one for
(I believe 24VDC) airplane supply. The output cable has a 5 pin
connector and there are a number of output adapters. A little
experimenting showed the output adapter sets the output voltage and
current limiting. Opening one up revealed three resistors, used to
set those parameters.

There are a couple of ways a supply can avoid sending an overvoltage
to a device. A fuse in the output and hoping the device has diode
protection would be one. While it would be possible to manufacture a
supply which ramps the voltage up until it hits a reasonable current
draw, it isn't very practical.

PlainBill

 

[micky]

On Sat, 16 Mar 2013 15:09:51 -0700, "William Sommerwerck"
<grizzledgeezer@comcast.net> wrote:

Variable-output power supplies have been around for many years.

The voltage is selected with a switch -- the supply doesn't "know" what
voltage is needed.

Here's the wall wart:
http://www.bestbuy.com/site/Dynex%26%23153%3B+-+Universal+AC/DC+Power+Adapter/3104194.p?id=1218378959348&skuId=3104194&st=power%20adapter&cp=3&lp=2

Dynex - Universal AC/DC Power Adapter dx-ac501
"Converts 120V AC to 3-12V DC
With 500mA maximum output.
For 3V, 4.5V, 6V, 7.5V, 9V and 12V power."

The picture only shows 3 sides of the thing, I'll open the box next
time I'm at BestBuy, to see if there are any switchers on the other 3
sides. .

For the laptop adapter, I looked some more and found
http://www.mp3car.com/power-supplies/90020-adjusting-the-targus-pa350-universal-dc-power-supply.html
It turns out there are interchangeable tips that each connect to the
power supply, and in each tip is a resistor. The wire from the PSU
has 3 wires and a shield in it, and if one connects the grey wire to
the yellow or the shield via a resistor, the value of the resistor and
whether one ues the yellow or the shield determines the output
voltage.

So you're right. It's told what voltage to make, although not so much
by a switch but by a resistor value in the tip.

Thanks for the help.

I've never seen one with continuously variable output.

Well, I don't know that it's really continuous. The text above
suggests that the wall wart can have 6 different outputs. And the
laptop power supply can have 30 different voltages, though I'm sure
not every one has a tip that yields it.

 

[John Fields]

On Sun, 17 Mar 2013 22:52:54 -0400, micky <NONONOmisc07@bigfoot.com>
wrote:

On Sat, 16 Mar 2013 15:09:51 -0700, "William Sommerwerck"
grizzledgeezer@comcast.net> wrote:

Variable-output power supplies have been around for many years.

The voltage is selected with a switch -- the supply doesn't "know" what
voltage is needed.

Here's the wall wart:
http://www.bestbuy.com/site/Dynex%26%23153%3B+-+Universal+AC/DC+Power+Adapter/3104194.p?id=1218378959348&skuId=3104194&st=power%20adapter&cp=3&lp=2

Dynex - Universal AC/DC Power Adapter dx-ac501
"Converts 120V AC to 3-12V DC
With 500mA maximum output.
For 3V, 4.5V, 6V, 7.5V, 9V and 12V power."

The picture only shows 3 sides of the thing, I'll open the box next
time I'm at BestBuy, to see if there are any switchers on the other 3
sides. .

---
It has a voltage selector switch.

Go to:

http://www.dynexproducts.com/products/cables-cords-adapters/DX-AC501.html

and click on "English" under "DOCUMENTATION"




--
JF

 

[micky]

On Sun, 17 Mar 2013 10:34:05 +1100, "Phil Allison" <phil_a@tpg.com.au>
wrote:

"micky"

I've gotten used to the idea that power bricks and other things can
accept 110 to 240 input volts and still put out the same output
voltage. Xener diodes, iirc, and all that.

** Such unit are SMPS = Switch Mode Power Supplies.


But lately I've been seeing wall warts and power supplies that not
only have variable input, they say they have variable OUTPUT. I saw
a little wallwart at Best Buy, for 10 or 15 dollars that said this,
(4.5 or 6 volts to 12 volts**) , and now I notice that my Targus
car/plane laptop power supply (which I've never actually used, except
one 3 minute test) says it puts out 4 to 22 volts DC.

How does it know which to do?

** It doesn't know.

No, I guess not. I am used to replaceable tips, but didn't expect
the tip to control the voltage.

YOU have to know and set the adjustments appropriately.

At least with the laptop power supply, I have to use the right tip.

Makes them a real hazard to use.

Well, it seems Targus got around that, in this universal power supply,
which is no longer made. I forget what they make now, and I don't
know how other manufacturers set the voltage.

How does the wallwart keep from overcharging with 12 volts a device
that needs only 6 volts?

** SMPS are not battery chargers.

Well, they do charge the battery of the laptop.

.... Phil

 

[Phil Allison]

"micky"

** SMPS are not battery chargers.

Well, they do charge the battery of the laptop.

** There is a charge regulator inside the laptop - fuckwit.

Wot a tool.


..... Phil

 

[micky]

On Mon, 25 Mar 2013 17:20:07 +1100, "Phil Allison" <phil_a@tpg.com.au>
wrote:

"micky"

** SMPS are not battery chargers.

Well, they do charge the battery of the laptop.

** There is a charge regulator inside the laptop - fuckwit.

That doesn't change anything. Kerplunk.

Wot a tool.


.... Phil