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RE: Finally a cheap possible wearable solution?

I'd recommend looking at Regulators from Digi-key..
PowerTrends (TI) has some small ones that are around
$15 a piece and require only a couple extra
capacitors.

I've seen them list some switching regulators that may
have both 5V and 12V... but I don't know what
additional electronic components this would require.

Rick

 --- Jeremy <> wrote: > got any
sources for a 12v output switching
> regualtor?
> 
> -----Original Message-----
> From: Jason Fox [mailto:]
> Sent: Monday, February 24, 2003 12:07 PM
> To: 
> Subject: RE: Finally a cheap possible wearable
> solution?
> 
> 
> This will certainly work but there are some
> considerations.  There are two
> main types of regulators, linear and switching.
> 
> Linear regulators work basically by knocking down
> your input voltage to the
> output voltage, this is done by turning the excess
> energy into heat ( =
> wasted energy unless you are making a pocket
> warmer).  All linear regulators
> have some amount of voltage differential between the
> minimum input and the
> output, for example a 12V output you would have a
> minimum input of about
> 12.7V  This minimum input voltage is important
> because at this point your
> output voltage becomes unpredictable, meaning that
> you really can only drain
> your batteries down to the minimum input voltage. 
> Your efficiency on a
> linear regulator is dependent on how much energy you
> waste by turning it
> into heat.
> 
> A switching regulator does a DC-AC and then a AC-DC
> conversion process.
> Because of this double conversion process (and some
> electronics inside) you
> have a nice input voltage range (9-18V, 12-30V, etc
> are common) that can
> actually be lower than your output voltage.  This is
> great for battery
> applications when your batteries can discharge to a
> voltage level lower than
> your electronics, you can use the full operation
> curve of the battery.
> Their efficiency is almost entirely dependent on the
> design, 70%-95% are
> common.  The down side is that they are usually much
> larger and much more
> expensive.
> 
> For testing purposes you may be able to get by with
> a linear regulator, but
> for any sort of regular usage you will be much
> happier with a switching
> regulator.
> 
> 
> 
> - Jason W Fox
> - Electronics Engineer
> - (202) 404-3736
> - SPG, ENEWS, Code 5707
> - Tactical Electronic Warfare Division, Naval
> Research Lab
> - Washington, DC
> 
> 
> -----Original Message-----
> From: Jeremy [mailto:]
> Sent: Monday, February 24, 2003 15:44
> To: 
> Subject: RE: Finaly a cheap possible wearable
> solution?
> 
> 
> "It might not hurt, though, to use a 13.2v or 14.4v
> battery, and run it
> through a 12v regulator." - exactly what I was
> thinking.
> 
> -----Original Message-----
> From: ben [mailto:]
> Sent: Monday, February 24, 2003 10:47 AM
> To: ; Jeremy
> Subject: Re: Finaly a cheap possible wearable
> solution?
> 
> 
> It may not be neccesary to regulate the voltage from
> the batteries, I'm
> still
> not sure.  Generally, 12v is roughly the same thing
> as 11v or 13v, so the
> psu
> will PROBABLY accept it (Bryan seems to agree with
> this), but we can't
> really
> know until somebody tries it.
> 
> It might not hurt, though, to use a 13.2v or 14.4v
> battery, and run it
> through a 12v regulator.  This would probably allow
> you to discharge
> further,
> and still meet the 12v input of the psu.
> 
> My first step, once I have a working system, will
> probably be to hook a 12v
> 4AH NiMH battery (since I've already got the cells)
> directly into the psu,
> and measure my uptime while performing something
> intensive, like a kernel
> recompile.  If it's not satisfactory, I'll
> experiment with regulation and/or
> other batteries.
> 
> -ben
> 
> On Monday 24 February 2003 14:07, Jeremy wrote:
> > I was thinking about this this morning and I was
> > think that I would have to build some sort of
> voltage
> > "regulator", but I am not expert on batteries.
> even with
> > the 12v power supply... (which I assume is
> expecting 12
> > volts dc input) I would have to regulate the power
> from
> > the bats. I can't remember the information from my
> basic
> > electrical course.
> >
> > I am going to do the same thing as you.. I am
> going to
> > start puchasing my parts run the puppy off AC till
> I get
> > linux working. I will probably get it all together
> in a
> > project box of some sort then worry about DC
> power.
> >
> > I will post my parts list after work tonight.
> 
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