[Milsurplus] 12 to 24 volt conversion, the issue of cost

[Michael Tauson]

On Thu, Oct 8, 2009 at 12:52 PM, Tom Dawson <wb3akd at earthlink.net> wrote:
> I don't think anyone's recommending that you mortgage the farm for a new
> truck,

Yes!  Yes, they are!  They're all gathering around that purple
monstrocity with the green and orange trim and they're all pointing
and giggling.  Some of them should refrain from giggling ... but
that's just personal opinion.  :-D

> And threads tend to drift particularly if contributors pick up in the middle.

Wasn't there a post on what happens to a topic that included spell
checks, counter-spell checks, commentary on those who actually care
about spell checks etc?

> On your DC-DC converter project, I might recommend that you investigate
> boost converters as the inductors are a single winding.  I've made
> experimental converters with just a 555 driving the switch transistor.
> Regulation is achieved via adjusting the duty cycle (something other than a
> 555 is needed if you want to regulate this way, but the 555 is a good place
> to start).  National semiconductor has application which greatly notes on
> their controller chips and boost  supplies in general.

Hmmm ... I like National - always have.  That may be due to having so
much fun with their SC/MP processors & NIBL language.  555s are cheap
and available in SMD* form which is a good thing.  Regulation doesn't
have to be overly tight since what I'm anticipating will be a
relatively constant load.  On the other hand, if I go up in power I
may need to tighten it up a tad bit.  This is where the "PRC-47
running low power" scenario kicks in, although I don't have one and
don't know I'll ever be able to afford one.

* To those who think I should "get modern", please note.  I also do
SMDs and have for a while.  Is that modern enough or do I have to go
molecular to keep you happy?

> Also there is Linear Technology with a substantial line of switching
> regulator chips of various configurations.

Already got 'em tagged.  Thanks.  :-)

> The boost switcher appeals because of the simplicity of the inductor design
> and several amps can be achieved with inductances on the order of 50 uH if
> the frequency is high enough.  In practice you'll need to add input and
> output filtering to suppress the EMI.

For applications like this, I like high frequencies anyway (Filtering
is so much easier.) so I like the idea.  Will ferrite beads serve for
EMI filtering or do I need to be more aggressive?

> Anyway, some food for thought.

*nibble ... nibble ... CHOMP*

Thanks!

Best regards,

Michael, WH7HG
-- 
http://www.nationalmssociety.org/chapters/NTH/index.aspx
http://wh7hg.blogspot.com/
http://kludges-other-blog.blogspot.com
Hiki Nô!

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