Re: Generate -+5V from 12V


"Baron" <baron.nospam@xxxxxxxxxxxxxxxxxxxxxx> wrote in message
news:h0k0pa$d33$1@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx
ian field wrote:


"Jon Kirwan" <jonk@xxxxxxxxxxxxxxxxxxx> wrote in message
news:ebvq25d3k26ld9t48q8kts38ru89bv31ah@xxxxxxxxxx
On Mon, 08 Jun 2009 21:56:55 +0100, Baron
<baron.nospam@xxxxxxxxxxxxxxxxxxxxxx> wrote:

ian field wrote:


"Jon Kirwan" <jonk@xxxxxxxxxxxxxxxxxxx> wrote in message
news:80sq25hvh6cns0v3vin15mtn3absg1aq25@xxxxxxxxxx
On Mon, 8 Jun 2009 21:08:45 +0100, "ian field"
<gangprobing.alien@xxxxxxxxxxxx> wrote:


"Jon Kirwan" <jonk@xxxxxxxxxxxxxxxxxxx> wrote in message
news:9goq251ual7soq52aiestb3d8kqsr25mo7@xxxxxxxxxx
On Mon, 08 Jun 2009 05:15:35 -0400, "Michael A. Terrell"
<mike.terrell@xxxxxxxxxxxxx> wrote:

Jon Kirwan wrote:

On Mon, 08 Jun 2009 01:37:52 -0700, Jon Kirwan
<jonk@xxxxxxxxxxxxxxxxxxx> wrote:

On Mon, 08 Jun 2009 00:11:45 -0400, "Michael A. Terrell"
<mike.terrell@xxxxxxxxxxxxx> wrote:

Jon Kirwan wrote:

On Sun, 7 Jun 2009 17:10:26 -0700, "BobW"
<nimby_GIMME_SOME_SPAM@xxxxxxxxxxxxxx> wrote:


"vic" <news@xxxxxxxxxxxxx> wrote in message
news:4a291f7d$0$696$426a74cc@xxxxxxxxxxxxxxx
Hi,

I need to generate a symmetric +/-5V supply from a
single +12V supply. I
need about 150mA from the +5V side, and less than 50mA
from the -5V side.

I've thought about using two 7805 in the following
configuration
:


Supply + ----+--------[7805]---- +5 V
| |
`-[7805]----+------ 0v
|
Supply - ---------+------------- -5V


does it make sense ? Would it be OK for the 7805 to
sink current
instead
of sourcing current, in the case of the 7805 in charge
of the 0V
supply ?

If this idea is garbage, what would be the recommended
solution to this
problem ?

Thanks.

See alt.binaries.schematics.electronic for a (linear)
circuit that
will work
up to about 200mA on each supply with a minimum input
voltage of 10.6V.

Sadly, Verizon (and other major service providers) have
completely
eliminated all alt.* groups from their servers. This
affects me, as
well. It may yet force me to get an extra-cost service
added.

I know I've posted this link at least a dozen times. It
is a
read
only portal for selected binaries newsgroups.

http://www.usenet-replayer.com/

First time it got my attention. I'll give it a shot.

Thanks,
Jon

Okay. It got my attention long enough to register and check
for the
group, alt.binaries.schematics.electronic. It doesn't appear
on their
list. Besides, they don't support NNTP and would be quite
difficult to make use of, if I understand what this means.

In short, it doesn't look usable for this purpose because it
doesn't
include the group. And it doesn't look usable, more
generally, because the mechanism (emailing every message, or
every message of a thread) isn't a means I would willingly
choose.

that's strange, because I've used it when the Earthlink news
farm was
dying. It is like Google groups, except it is a read only
portal. I
used it when someone mentioned a binary file on the group. The
propogation is slow, but most binaries from the group do end up
there.

http://www.usenet-replayer.com/groups/alt.binaries.schematics.electronic.html

Thanks. What I did before was to go to the main page at which
you referred me and then clicked on "get the USENET messages"
link. That took me to:

http://www.usenet-replayer.com/sign_up_feed.html

I then went through the process of signing up. They sent me an
email,
which I saved and edited into an HTML page. Loaded that, then
clicked
on the "Feed On" button. (I gather they allow me to sign up for
10
different groups.) When I clicked that JAVA link, it set me up
on a page where I could ask it to display the ALT groups I might
want to
include in my 10. alt.binaries.schematics.electronic wasn't in
the list.

What you've shown me is something different. It appears to be a
bit
strange. I'm struggling with the format, which appears to only
be the
pictures and no text bodies when messages don't include
pictures. If so, that means I may be able to access pictures
this way but not
comments sent to the group about them. Threading seems... well,
I'm
not seeing how, yet. It looks as though I may be able to pick
up on
some pictures this way, though. If I'm quick about it...
otherwise I may have to weed through pages and hope that my eye
can pick out what I'm looking for in the thumbnails.

Perhaps they don't include alt.binaries.schematics.electronic in
their emailing service, but do offer a web page with
pictures-only component from the group?

Jon

Google for binary news server - there's some freebies listed.

I did, some time ago. Finding a good NNTP server that includes a
binary newsgroup like alt.binaries.schematics.electronic was a "no
show." I spent the spare time of a few days on it. Not looking
forward to that, again. Especially, if someone has a specific
idea on hand that does NNTP for that group in particular.

Of course, when I get a strong enough interest to push the time
envelop out some more in the future, I'll take another shot at it.

But for now, yeah. Been there, done that, came up zero.

Jon

One I clicked on installed as server name: 202.177.16.1321 it seems
to work and carries alt.binaries,schematics.electronic

Ian. Would you like to correct that ip 202.177.16.??? I guessing
its
132. Since that responds with "Operation in Progress"

Hehe. 1321 is indeed impossible -- at least with the traditional
system which allows only up to 255.

Jon

Here's the right number again - 121

Thanks. That one works ! Its a bit slow but its got the
alt.binaries.schematics.electronic group. I also got the attached pdf.
Good one.

--
Best Regards:
Baron.

It also carries News:alt.binaries.e-book.technical from time to time there's
a huge collection of electronics books (that is the collection is re-posted
occasionally) and some of the electronics magazines get uploaded.


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