Re: Generate -+5V from 12V

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
.

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