small and board mount solutions for +5VDC AC-DC supply?

M

Michael Noone

Guest
Hi - I have a board I'm finishing up the design of right now that needs a
5V DC supply. It already has 120V AC live, neutral, and ground on it - so
ideally I'd like to be able to have something simple made use of those
lines instead of using a wall wart. Current consumption should be fairly
low - I believe around 30-50ma, certainly never over 100ma. I'm also hoping
to find something fairly efficient, as there won't be much cooling
available to this circuit. Any suggestions? Thanks!

-Michael J. Noone
 
On Sun, 29 May 2005 22:40:54 -0500, in sci.electronics.design Michael
Noone <mnoone.uiuc.edu@127.0.0.1> wrote:

Hi - I have a board I'm finishing up the design of right now that needs a
5V DC supply. It already has 120V AC live, neutral, and ground on it - so
ideally I'd like to be able to have something simple made use of those
lines instead of using a wall wart. Current consumption should be fairly
low - I believe around 30-50ma, certainly never over 100ma. I'm also hoping
to find something fairly efficient, as there won't be much cooling
available to this circuit. Any suggestions? Thanks!

-Michael J. Noone
www.powerint.com
Click to expand...



martin

"Wales is a big welsh-shaped rain collection device"
 
Michael Noone wrote:
Hi - I have a board I'm finishing up the design of right now that needs a
5V DC supply. It already has 120V AC live, neutral, and ground on it - so
ideally I'd like to be able to have something simple made use of those
lines instead of using a wall wart. Current consumption should be fairly
low - I believe around 30-50ma, certainly never over 100ma. I'm also hoping
to find something fairly efficient, as there won't be much cooling
available to this circuit. Any suggestions? Thanks!

-Michael J. Noone
Click to expand...
If the board doesn't have to be isolated, you can use a capacitor to
block the line, followed by a bridge and a shunt regulator. Here is a
technote by microchip that describes some techniques:

http://tinyurl.com/bnznd

---
Regards,
Bob Monsen
 
Michael Noone wrote:

Hi - I have a board I'm finishing up the design of right now that needs a
5V DC supply. It already has 120V AC live, neutral, and ground on it - so
ideally I'd like to be able to have something simple made use of those
lines instead of using a wall wart. Current consumption should be fairly
low - I believe around 30-50ma, certainly never over 100ma. I'm also hoping
to find something fairly efficient, as there won't be much cooling
available to this circuit. Any suggestions? Thanks!
Click to expand...
Stick with the wallwart supply.
By using an external powersupply, only this supply has
to conform to the legal rules. Otherwise your gadget
has to conform to the rules. Conforming to the rules
can be a costly undertaking as the required tests
differ quite a lot.

Rene
--
Ing.Buero R.Tschaggelar - http://www.ibrtses.com
& commercial newsgroups - http://www.talkto.net
 
bill.sloman@ieee.org wrote:
Since the board already has 120V AC live, neutral and ground, it will
have to conform to the legal rules in any event.

I'd use a small step-down transformer, a diode bridge, about 1000uF of
electrolytic reservour capacitor, and 5V linear regulator in a TO-220
package - something like the LM340 or an LM7805. A low-drop-out
regulator wouldn't be worth the trouble in this sort of application.

A capacitative voltage dropper sounds attractive until you start
working out to protect it from the fast, high-voltage spikes that show
up from time to time on the mains.
Click to expand...
Would it be possible to use a transient voltage suppressor to help with
this problem? How about something like this:

http://www.fairchildsemi.com/pf/SM/SMCJ100A.html

---
Regards,
Bob Monsen
 
Bob Monsen wrote:

Michael Noone wrote:

Hi - I have a board I'm finishing up the design of right now that
needs a 5V DC supply. It already has 120V AC live, neutral, and ground
on it - so ideally I'd like to be able to have something simple made
use of those lines instead of using a wall wart. Current consumption
should be fairly low - I believe around 30-50ma, certainly never over
100ma. I'm also hoping to find something fairly efficient, as there
won't be much cooling available to this circuit. Any suggestions? Thanks!

-Michael J. Noone


If the board doesn't have to be isolated, you can use a capacitor to
block the line, followed by a bridge and a shunt regulator. Here is a
technote by microchip that describes some techniques:

http://tinyurl.com/bnznd

---
Regards,
Bob Monsen
Ther are a number of switching regulators designed to do just that.
Click to expand...
 
Michael Noone <mnoone.uiuc.edu@127.0.0.1> wrote in message
news:Xns9665D25835B2Dmnooneuiucedu127001@216.196.97.136...
Hi - I have a board I'm finishing up the design of right now that needs a
5V DC supply. It already has 120V AC live, neutral, and ground on it - so
ideally I'd like to be able to have something simple made use of those
lines instead of using a wall wart. Current consumption should be fairly
low - I believe around 30-50ma, certainly never over 100ma. I'm also
hoping
to find something fairly efficient, as there won't be much cooling
available to this circuit. Any suggestions? Thanks!

-Michael J. Noone
Click to expand...
Take a look at:

http://www.biaspower.com/

Don Cleveland
 
"Don Cleveland" <dlclevel_nospam@eagle.ca> wrote in
news:B0Ome.8258$5u4.27165@nnrp1.uunet.ca:

Michael Noone <mnoone.uiuc.edu@127.0.0.1> wrote in message
news:Xns9665D25835B2Dmnooneuiucedu127001@216.196.97.136...
Hi - I have a board I'm finishing up the design of right now that
needs a 5V DC supply. It already has 120V AC live, neutral, and
ground on it - so ideally I'd like to be able to have something
simple made use of those lines instead of using a wall wart. Current
consumption should be fairly low - I believe around 30-50ma,
certainly never over 100ma. I'm also
hoping
to find something fairly efficient, as there won't be much cooling
available to this circuit. Any suggestions? Thanks!

-Michael J. Noone

Take a look at:

http://www.biaspower.com/

Don Cleveland
Click to expand...
Hi Don - that is *exactly* what I'm looking for. I contacted them and these
units are new and have not made it out of production yet, and will not
until August. Are there any companies out there that make similar products?
Again - this is exactly what I'm looking for, but I'm hoping to get the
parts sooner than that. Thanks,

-Michael Noone
 
martin griffith <martingriffith@XXyahoo.co.uk> wrote in
news:cq7l915ov9acnf6fud0tlqm5mo84mdkk4c@4ax.com:

On Sun, 29 May 2005 22:40:54 -0500, in sci.electronics.design Michael
Noone <mnoone.uiuc.edu@127.0.0.1> wrote:

Hi - I have a board I'm finishing up the design of right now that
needs a 5V DC supply. It already has 120V AC live, neutral, and ground
on it - so ideally I'd like to be able to have something simple made
use of those lines instead of using a wall wart. Current consumption
should be fairly low - I believe around 30-50ma, certainly never over
100ma. I'm also hoping to find something fairly efficient, as there
won't be much cooling available to this circuit. Any suggestions?
Thanks!

-Michael J. Noone
www.powerint.com



martin

"Wales is a big welsh-shaped rain collection device"
Click to expand...
I'm not quite sure what I should be looking for at this website? I looked
through their product catalog and did not see anything at all like what I'm
looking for. Thanks,

-Michael
 
bill.sloman@ieee.org wrote in news:1117445015.906720.34530
@z14g2000cwz.googlegroups.com:

Since the board already has 120V AC live, neutral and ground, it will
have to conform to the legal rules in any event.

I'd use a small step-down transformer, a diode bridge, about 1000uF of
electrolytic reservour capacitor, and 5V linear regulator in a TO-220
package - something like the LM340 or an LM7805. A low-drop-out
regulator wouldn't be worth the trouble in this sort of application.

A capacitative voltage dropper sounds attractive until you start
working out to protect it from the fast, high-voltage spikes that show
up from time to time on the mains.

-----------
Bill Sloman, Nijmegen
Click to expand...
You're quite correct about the legalities Bill. My plan was to do like you
said with a step down transformer, but I got to thinking that there just
*has* to be an easier way, as this seems like a pretty common task. Also
all the transformers I've been looking at are fairly large, and I'm hoping
to keep this board as small as possible.

-Michael
 
On Sun, 29 May 2005 22:40:54 -0500, Michael Noone wrote:

Hi - I have a board I'm finishing up the design of right now that needs a
5V DC supply. It already has 120V AC live, neutral, and ground on it - so
ideally I'd like to be able to have something simple made use of those
lines instead of using a wall wart. Current consumption should be fairly
low - I believe around 30-50ma, certainly never over 100ma. I'm also hoping
to find something fairly efficient, as there won't be much cooling
available to this circuit. Any suggestions? Thanks!

What if you just attached something like this to the board, instead
Click to expand...
of a transformer/rectifier/filter/regulator?
http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&product%5Fid=273-1662

I can't imagine this being the only thing like it - I just went to
radioshack.com and looked up "adapters".

Cheers!
Rich
 
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