Amplifier transistor matching?

[jakdedert]

Joerg wrote:

Hello Richard,

And cell-phone manufacturers regularly plumb the depths of
low-res to see how much we will put up with!

Yes, it seems so. It could be the carriers since their currency is
kb/sec. Yesterday a long time friend called me on his cell phone. I
could not even recognize who it was until several seconds into the
conversation, and initially only by what he was talking about.

Regards, Joerg

They need to save their bandwidth for pictures & video....

jak

http://www.analogconsultants.com

 

[Joerg]

Hello Mr.T,

So the answer may be to use a larger 9V battery. Unfortunately these aren't
common any more. Most people prefer to use the smaller size, and change it
more often.

Since AA packs a lot more Watthours per cubic inch than a 9V I think it
would great if all designers wised up and designed their stuff to work
with AA or a couple of them. It's not rocket science. I had a radio
30-some years ago that worked nicely with two AA. It boasted the longest
runtime on one set of any radio I ever had. Got lost in a move and now I
am using a 9V radio. It doesn't even last a day and the batteries cost
twice as much.

Regards, Joerg

http://www.analogconsultants.com

 

[Joerg]

Hello Jak,

They need to save their bandwidth for pictures & video....

Let's see how that goes. Maybe it's like with pool heaters. People love
it until that first bill arrives in the mail.

Regards, Joerg

http://www.analogconsultants.com

 

[Joerg]

Hello Rich,

And who amongst us isn't old enough to remember SSB? ;-) You can
pick voice information out of an incredible amount of noise!

Hey, I am old enough to remember CW. With morse code it has been said
that the trained ear was on occasion able to beat Shannon's law. Depends
on the imbabitation status though.

Regards, Joerg

http://www.analogconsultants.com

 

[Rich Grise]

On Sat, 11 Jun 2005 20:35:09 +0000, Joerg wrote:

Hello Mr.T,

So the answer may be to use a larger 9V battery. Unfortunately these aren't
common any more. Most people prefer to use the smaller size, and change it
more often.

Since AA packs a lot more Watthours per cubic inch than a 9V I think it
would great if all designers wised up and designed their stuff to work
with AA or a couple of them. It's not rocket science. I had a radio
30-some years ago that worked nicely with two AA. It boasted the longest
runtime on one set of any radio I ever had. Got lost in a move and now I
am using a 9V radio. It doesn't even last a day and the batteries cost
twice as much.

Hasn't someone already mentioned the 6X AAA pack? Only a few mm bigger
than a 9V, but lasts considerably longer? There are such a thing as
AAA NiMHs, aren't there? My magical charger seems to think so:
http://www.neodruid.org/images/NiMH-Charger.jpg

I swear, that little box is smarter than I am [not that that's that
great of an accomplishment] when it comes to charging NiMHs.

And does anybody remember "The Secret of NIMH"?

Cheers!
Rich

 

[Ian Stirling]

In sci.electronics.design Spehro Pefhany <speffSNIP@interlogdotyou.knowwhat> wrote:

On Fri, 10 Jun 2005 19:32:17 GMT, the renowned Tom MacIntyre
tom__macintyre@hotmail.com> wrote:



I remember reading years ago that the spoken human voice could be
intelligible at a quite high distortion level. I think the amplifier
in question was 30% or somesuch, but that sounds high even to me now.
Depending on the venue, even room acoustics may outweigh any
distortion issues, I'd guess. Think of the US National Anthem sung at
a sports venue...


"for th or e la and e nd of...you get my drift.

Years ago, I heard a demo of the human voice with 1-bit resolution. It
was understandable, but not at all pleasant.

I've clocked high-pass (300Hz) signals through a 3Khz flip-flop.
Surprisingly good, using a speech radio station as a signal source.

 

[Richard Crowley]

"Joerg" wrote ...

Hey, I am old enough to remember CW. With morse code it has been said
that the trained ear was on occasion able to beat Shannon's law.

But so far we have not been able to even think of approaching the
speed and functionality of the human brain with any kind of
computer. There were seveal levels of "intelligence" operating
to decode CW in heavy QRM/QRN.

 

[John Larkin]

On Sat, 11 Jun 2005 20:39:29 GMT, Joerg
<notthisjoergsch@removethispacbell.net> wrote:

Hello Rich,

And who amongst us isn't old enough to remember SSB? ;-) You can
pick voice information out of an incredible amount of noise!

Hey, I am old enough to remember CW. With morse code it has been said
that the trained ear was on occasion able to beat Shannon's law. Depends
on the imbabitation status though.

On a bit-by-bit basis, probably not. But on a symbol basis, where a
symbol is a word, probably so. Especially if the vocabulary is small
and there's surrounding context.

It's just a matter of defining "symbol."

John

 

[keith]

On Sat, 11 Jun 2005 20:37:00 +0000, Joerg wrote:

Hello Jak,

They need to save their bandwidth for pictures & video....

Let's see how that goes. Maybe it's like with pool heaters. People love
it until that first bill arrives in the mail.

What amazes me is the cost of text-messaging. Why do I want to do that
again?

I've ditched my land-line and gone cell, but there are many things that
make no sense. Land-lines are expensive because the government decides it
is so, but that doesn't excuse the cell companies from sanity. Sure, I
know, it's all the teeny-boppers that think text-messaging is cool.

--
Keith

 

[keith]

On Sat, 11 Jun 2005 17:23:16 -0700, John Larkin wrote:

On Sat, 11 Jun 2005 20:39:29 GMT, Joerg
notthisjoergsch@removethispacbell.net> wrote:

Hello Rich,

And who amongst us isn't old enough to remember SSB? ;-) You can
pick voice information out of an incredible amount of noise!

Hey, I am old enough to remember CW. With morse code it has been said
that the trained ear was on occasion able to beat Shannon's law. Depends
on the imbabitation status though.


On a bit-by-bit basis, probably not. But on a symbol basis, where a
symbol is a word, probably so. Especially if the vocabulary is small
and there's surrounding context.

It's just a matter of defining "symbol."

....and if the data-rate exceeds Shannon, your "symbol" is defined wrong.
;-)

The other thing people forget is the institutional and personal
information that preceeds the communication. Many CWers knew the "fist"
of others and their "expressions". This information was transmitted,
albeit via a side-channel. ...data comperession with a known dictionary,
as it were.

--
Keith


--
Keith

 

[Ian Stirling]

In sci.electronics.design keith <krw@att.bizzzz> wrote:

On Sat, 11 Jun 2005 20:37:00 +0000, Joerg wrote:

Hello Jak,

They need to save their bandwidth for pictures & video....

Let's see how that goes. Maybe it's like with pool heaters. People love
it until that first bill arrives in the mail.

What amazes me is the cost of text-messaging. Why do I want to do that
again?

Time?

I've ditched my land-line and gone cell, but there are many things that
make no sense. Land-lines are expensive because the government decides it
is so, but that doesn't excuse the cell companies from sanity. Sure, I
know, it's all the teeny-boppers that think text-messaging is cool.

If you feel comfortable talking to people by just reciting a message,
then you can probably get it done faster/cheaper.

But, how often is that the case?
Many people on the other end will digress into weather/how their dog is/...

 

[Mr.T]

"Rich Grise" <richgrise@example.net> wrote in message
newsan.2005.06.11.23.41.21.110591@example.net...

Since AA packs a lot more Watthours per cubic inch than a 9V

Does it? I'm interested in your calculations.
There should be a market then for someone to simply put the exact same
technology into a 9V pack.

I think it
would great if all designers wised up and designed their stuff to work
with AA or a couple of them. It's not rocket science. I had a radio
30-some years ago that worked nicely with two AA.

It's even easier now with DC-DC switching converters.

Hasn't someone already mentioned the 6X AAA pack? Only a few mm bigger
than a 9V,

Wow, either your AAA are smaller than ours, or your talking about bigger 9V
batteries than I am.
Including a cell holder makes our 6*AAA packs over twice as big as a single
9V battery with snap.
Even without a cell holder they still have quite a bit more volume.

MrT.

 

[Ken Smith]

In article <42ad3d04$0$1797$afc38c87@news.optusnet.com.au>,
Mr.T <MrT@home> wrote:

"Rich Grise" <richgrise@example.net> wrote in message
newsan.2005.06.11.23.41.21.110591@example.net...
Since AA packs a lot more Watthours per cubic inch than a 9V

Does it? I'm interested in your calculations.
There should be a market then for someone to simply put the exact same
technology into a 9V pack.

Pry apart a 9V and you will see why the AA packs more energy per unit
volume. There is a lot of the internal space used up by the need to
interconnect the cells and isolate them from each other.

I suspect that the cells in the 9V are actually a little better than the
AA in energy per volume but I don't think it is by enough to make up for
the about 1/3rd of the space that is not actually a cell.


--
--
kensmith@rahul.net forging knowledge

 

[Spehro Pefhany]

On Mon, 13 Jun 2005 14:03:35 +0000 (UTC), the renowned
kensmith@green.rahul.net (Ken Smith) wrote:

In article <42ad3d04$0$1797$afc38c87@news.optusnet.com.au>,
Mr.T <MrT@home> wrote:

"Rich Grise" <richgrise@example.net> wrote in message
newsan.2005.06.11.23.41.21.110591@example.net...
Since AA packs a lot more Watthours per cubic inch than a 9V

Does it? I'm interested in your calculations.
There should be a market then for someone to simply put the exact same
technology into a 9V pack.

Pry apart a 9V and you will see why the AA packs more energy per unit
volume. There is a lot of the internal space used up by the need to
interconnect the cells and isolate them from each other.

I suspect that the cells in the 9V are actually a little better than the
AA in energy per volume but I don't think it is by enough to make up for
the about 1/3rd of the space that is not actually a cell.

Comparing the consumer cells/batteries at a given point in time from
one manufacturer (GP), you have the capacity of their highest capacity
AA cells is typically 2450mAh (marked "2500"), while(st) their highest
capacity 9V battery is 210mAh (marked 200). Since the 9V battery is 7
cells in series, the 9V battery has only 60% of the energy storage
capacity of the AA cell.

On a weight basis, the 9V battery is 42.5g and the AA cells is 31g, so
the AA cell comes out even further ahead (2.28:1).

On a volume basis, the AA cell fits in a cylinder 14.5mm diameter by
50.5mm long (including the end button), so 8339mm^3. The 9V battery
fits in a box 48.5mm x 26.5mm x 15.7mm (including the snaps) or
20,180mm^3.

On a volume basis, the AA cell comes out ahead by 4:1. If you more
realistically use a box (rectangular prism) that just encloses the AA
cylinder for the occupied volume, it's still ahead by more than 3:1.



Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

 

[Mr.T]

"Ken Smith" <kensmith@green.rahul.net> wrote in message
news:d8k3nn$cra$1@blue.rahul.net...

Does it? I'm interested in your calculations.
There should be a market then for someone to simply put the exact same
technology into a 9V pack.

Pry apart a 9V and you will see why the AA packs more energy per unit
volume. There is a lot of the internal space used up by the need to
interconnect the cells and isolate them from each other.

So the casing of a AAA cell (and cell holder) doesn't do exactly the same?
Not to mention all that wasted area between cylindrical cells.

I suspect that the cells in the 9V are actually a little better than the
AA in energy per volume but I don't think it is by enough to make up for
the about 1/3rd of the space that is not actually a cell.

I note you have included NO data to back up your assertion.
Your claim of more energy per unit volume is looking dubious then.

MrT.

 

[Mr.T]

"Spehro Pefhany" <speffSNIP@interlogDOTyou.knowwhat> wrote in message
news:2u6ra1tqrciomic8bkb7llehbjb7h5umsj@4ax.com...

Comparing the consumer cells/batteries at a given point in time from
one manufacturer (GP), you have the capacity of their highest capacity
AA cells is typically 2450mAh (marked "2500"), while(st) their highest
capacity 9V battery is 210mAh (marked 200). Since the 9V battery is 7
cells in series, the 9V battery has only 60% of the energy storage
capacity of the AA cell.

Interesting to see some actual data for a change, however it would be more
appropriate to compare batteries of the same range, and similar size. I am
not familiar with the GP cells you refer to, but I suspect the top of the
range AA cell is a newer technology. If you now use D cells instead, the
figures are MUCH greater in favour of D cells than AA.
Obviously by your reasoning nobody should ever use AA cells since D cells
are far better!

In fact using only one D cell with a DC-DC inverter *IS* the best way to
power most equipment!
I'll let you do the calculations, then compare the cost of one D cell versus
six AA cells!!!!!!!!!

Personally I would NEVER consider six AA cells as a good replacement for a
9V battery when a **FAR** better option exists.

On a weight basis, the 9V battery is 42.5g and the AA cells is 31g, so
the AA cell comes out even further ahead (2.28:1).

And a D cell much further still.
Now where are the figures for six AAA cells and battery holder?

On a volume basis, the AA cell fits in a cylinder 14.5mm diameter by
50.5mm long (including the end button), so 8339mm^3. The 9V battery
fits in a box 48.5mm x 26.5mm x 15.7mm (including the snaps) or
20,180mm^3.

Shame you cannot use that wasted space between cells.

On a volume basis, the AA cell comes out ahead by 4:1. If you more
realistically use a box (rectangular prism) that just encloses the AA
cylinder for the occupied volume, it's still ahead by more than 3:1.

As is the size difference unfortunately.

MrT.

 

[Spehro Pefhany]

On Tue, 14 Jun 2005 15:28:57 +1000, the renowned "Mr.T" <MrT@home>
wrote:

"Spehro Pefhany" <speffSNIP@interlogDOTyou.knowwhat> wrote in message
news:2u6ra1tqrciomic8bkb7llehbjb7h5umsj@4ax.com...
Comparing the consumer cells/batteries at a given point in time from
one manufacturer (GP), you have the capacity of their highest capacity
AA cells is typically 2450mAh (marked "2500"), while(st) their highest
capacity 9V battery is 210mAh (marked 200). Since the 9V battery is 7
cells in series, the 9V battery has only 60% of the energy storage
capacity of the AA cell.

Interesting to see some actual data for a change, however it would be more
appropriate to compare batteries of the same range, and similar size. I am
not familiar with the GP cells you refer to, but I suspect the top of the
range AA cell is a newer technology.

Really, who cares?

This manufacturer has a wide line with three types of 9V cell alone.
You think they're going to improve the 9V cell just for you? The AA
cells have not made a sudden leap in capacity. Every six months or
year they introduce an new model that is slightly better in capacity.
They sell the lower capacity cells in lower cost markets such as
mainland China (in fact, they're the only ones available). If D cells
and 9V batteries are unpopular with product designers and therefore
don't have the same competitive pressure to make high-performance
designs, that's taken into account by looking at the "best available"
units.

If you now use D cells instead, the
figures are MUCH greater in favour of D cells than AA.
Obviously by your reasoning nobody should ever use AA cells since D cells
are far better!

Only in energy storage per battery.

*If* you read and understood my entire post, you would have seen the
other two comparisons-- of energy storage per gram and energy storage
per unit volume. In *all* cases, the best available AA cell of that
brand/series beats the best available 9V cell of that brand/series by
a considerable margin.

In fact using only one D cell with a DC-DC inverter *IS* the best way to
power most equipment!
I'll let you do the calculations, then compare the cost of one D cell versus
six AA cells!!!!!!!!!

Why don't *you* do some calculations? It should be trivially easy to
find the data and the mensuration formulas if you don't remember them.

Personally I would NEVER consider six AA cells as a good replacement for a
9V battery when a **FAR** better option exists.

Who said anything about six? It takes seven to equal the voltage of a
typical 9V battery (some are higher), and my comparison was for a
single cell vs. a 9V battery. Hopefully it's easy enough to multiply
by the number of batteries in the case of total capacity. It won't
affect the energy storage per gram or per cubic millimeter numbers,
obviously!

On a weight basis, the 9V battery is 42.5g and the AA cells is 31g, so
the AA cell comes out even further ahead (2.28:1).

And a D cell much further still.

Got any numbers to back up that (quite dubious) assertion?

Now where are the figures for six AAA cells and battery holder?

Waiting for you to calculate them. I have no need of the numbers at
present.

On a volume basis, the AA cell fits in a cylinder 14.5mm diameter by
50.5mm long (including the end button), so 8339mm^3. The 9V battery
fits in a box 48.5mm x 26.5mm x 15.7mm (including the snaps) or
20,180mm^3.

Shame you cannot use that wasted space between cells.

In some cases some of it can be used by a clever designer. It can't be
if the space is filled by a steel shell.

On a volume basis, the AA cell comes out ahead by 4:1. If you more
realistically use a box (rectangular prism) that just encloses the AA
cylinder for the occupied volume, it's still ahead by more than 3:1.

As is the size difference unfortunately.

MrT.

The AA cell is >3 times better than a 9V battery in *energy per cubic
millimeter*. "Size difference" is already taken into account in this
number. You want to take it into account again?


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

 

[Arny Krueger]

Spehro Pefhany wrote:

On a volume basis, the AA cell fits in a cylinder 14.5mm
diameter by
50.5mm long (including the end button), so 8339mm^3. The
9V battery
fits in a box 48.5mm x 26.5mm x 15.7mm (including the
snaps) or
20,180mm^3.

Readily available DC-DC converters seem to want at least 2.7
volts input voltage, to produce 5 volts. So, you're stuck
with using 2 AA cells, which are somewhat longer and wider
than one 9 volt cell.

OTOH, Maxim shows a wide range of converters with inputs as
low as 0.6 volts and plenty rated at 1.5 volt input. A wide
range of output voltages is listed as well.

http://para.maxim-ic.com/compare.asp?Fam=DCDC_All&Tree=PowerSupplies&HP=PowerSupplies.cfm&ln=&SORD=1751&FT_1751=21300&ITEMLIST=15C03,15C04,15C05,15C06,15C09,15C0A,15C1A,15C1B,15C26,15C27,15C28,15C2A,15C33,15C34,15C37,15C38,15C39,15C3A,15C3B,15C3C,15C53,15C56,15C57,15C5C,15C5E,15C5F,15C60,15C68,15C69,15C6A,15C6B,15C82,15C83,15C84,15C89,15C8A,15C8B,15C93,15C94,15C99,15CA9,15CAA,15CAB,15CAC,15CB2,15CBA,15CBB,15CBF,15CC0,15CC3,15CC4,15CCC,15CCD,15CCE,15CCF,15CE9,15CEA,15CEF,15CF0,15CF1,15CF2,15CF8,15CF9,15D07,15D08,15D0D,15D0E,15D0F,15D10,15D11,15D12,15D13,15D1A,15D1B,15D1C,15D1D,15D1E,15D34,15D46,15D47,15D48,15D5F,15D67,15D68,15D69,15D86,15D87,15D92,15D97,15DAE,15DAF,15DB0,15DB1,15DB2,15DB3,15DB4,15DB9,15DBA,15DBB,15DBC,15DBD,15DC0

On a volume basis, the AA cell comes out ahead by 4:1. If
you more
realistically use a box (rectangular prism) that just
encloses the AA
cylinder for the occupied volume, it's still ahead by more
than 3:1.

It looks like the DC-DC converter could be packaged so it
had about 1/6 the volume of a 9 volt battery.

All things considered the 2-AA cell solution is still ahead
by something like 2:1 in terms of power per volume, but at a
significant cost in terms of minimum size and cost.

It's probably the cost that dominates most design decisions
for consumer products. A DC-DC converter could add $20-30 to
the final cost.

It seems like a single-AA cell solution could be practical
for higher end wireless mics and earphones for pro audio,
for example.

 

[Arny Krueger]

Spehro Pefhany wrote:

On Tue, 14 Jun 2005 07:54:25 -0400, the renowned "Arny
Krueger"
arnyk@hotpop.com> wrote:

Spehro Pefhany wrote:

On a volume basis, the AA cell fits in a cylinder 14.5mm
diameter by
50.5mm long (including the end button), so 8339mm^3. The
9V battery
fits in a box 48.5mm x 26.5mm x 15.7mm (including the
snaps) or
20,180mm^3.

Readily available DC-DC converters seem to want at least
2.7
volts input voltage, to produce 5 volts. So, you're stuck
with using 2 AA cells, which are somewhat longer and
wider
than one 9 volt cell.

Many of the current crop of flash MP3 players seem to use
a single
alkaline or NiMH AAA cell.

I don't know what they use for power internally. Based on
the limited headphone drive they provide, they may in fact
be running off the 1.5 volt directly.

OTOH, Maxim shows a wide range of converters with inputs
as
low as 0.6 volts and plenty rated at 1.5 volt input. A
wide
range of output voltages is listed as well.


http://para.maxim-ic.com/compare.asp?Fam=DCDC_All&Tree=PowerSupplies&HP=PowerSupplies.cfm&ln=&SORD=1751&FT_1751=21300&ITEMLIST=15C03,15C04,15C05,15C06,15C09,15C0A,15C1A,15C1B,15C26,15C27,15C28,15C2A,15C33,15C34,15C37,15C38,15C39,15C3A,15C3B,15C3C,15C53,15C56,15C57,15C5C,15C5E,15C5F,15C60,15C68,15C69,15C6A,15C6B,15C82,15C83,15C84,15C89,15C8A,15C8B,15C93,15C94,15C99,15CA9,15CAA,15CAB,15CAC,15CB2,15CBA,15CBB,15CBF,15CC0,15CC3,15CC4,15CCC,15CCD,15CCE,15CCF,15CE9,15CEA,15CEF,15CF0,15CF1,15CF2,15CF8,15CF9,15D07,15D08,15D0D,15D0E,15D0F,15D10,15D11,15D12,15D13,15D1A,15D1B,15D1C,15D1D,15D1E,15D34,15D46,15D47,15D48,15D5F,15D67,15D68,15D69,15D86,15D87,15D92,15D97,15DAE,15DAF,15DB0,15DB1,15DB2,15DB3,15DB4,15DB9,15DBA,15DBB,15DBC,15DBD,15DC0

On a volume basis, the AA cell comes out ahead by 4:1.
If
you more
realistically use a box (rectangular prism) that just
encloses the AA
cylinder for the occupied volume, it's still ahead by
more
than 3:1.

It looks like the DC-DC converter could be packaged so it
had about 1/6 the volume of a 9 volt battery.

Chances are you're going to use a switching regulator
anyway if you
want good battery life. Otherwise you're probably throwing
away more
than half the energy.

The deviced I've referenced are all based on switchmode
operation.

All things considered the 2-AA cell solution is still
ahead
by something like 2:1 in terms of power per volume, but
at a
significant cost in terms of minimum size and cost.

It's probably the cost that dominates most design
decisions
for consumer products. A DC-DC converter could add $20-30
to
the final cost.

It's a complex comparison-- case size, styling, and
battery life and
often charger considerations have to be taken into account
in a
portable product. I don't know how much the newest small
stepup
converters cost in consumer production volume, but mature
SMPS chips
are in the 10 to 20-cent range. The newest ones could be 5
or 10 times
that, even in volume.

The prices I see are in the 10x range.

The size of things like digital cameras, games etc. have
decreased to
the point where they often insist on newer types of
batteries. These
things are expensive to replace, and you can't take
advantage of
improvements in technology. My first digital camera took 4
AA cells,
and I now use 2450mAh batteries in it. The first ones were
1300mAh.
That's a considerable improvement (over 6 years). My more
recent
purchases use special Li-ion batteries. At least one
company is
pushing security chips to prevent the use of third-party
battery packs
in new designs. Li-ion cells also need a more
sophisticated charger
technology AFAIUI.

But compare a typical Li-ion cell-

3.7V output. 5.5mm x 34mm x 50.4mm and only 21 grams.
860mAh at 3.7V.
That's almost half the thickness of a AAA cell and has
about the
energy storage capacity and voltage output of 3 typical
AAA cells.
Very tempting.

Agreed, and no DC-DC converter would be required.

It seems like a single-AA cell solution could be
practical
for higher end wireless mics and earphones for pro audio,
for example.

Yes, I would think it would be good. Or even a AAA*.
But the little flat Li-ion batteries would be even
sleeker.

Trouble with the Li-ion cells is that every device seems to
want a different one.

 

[Spehro Pefhany]

On Tue, 14 Jun 2005 07:54:25 -0400, the renowned "Arny Krueger"
<arnyk@hotpop.com> wrote:

Spehro Pefhany wrote:

On a volume basis, the AA cell fits in a cylinder 14.5mm
diameter by
50.5mm long (including the end button), so 8339mm^3. The
9V battery
fits in a box 48.5mm x 26.5mm x 15.7mm (including the
snaps) or
20,180mm^3.

Readily available DC-DC converters seem to want at least 2.7
volts input voltage, to produce 5 volts. So, you're stuck
with using 2 AA cells, which are somewhat longer and wider
than one 9 volt cell.

Many of the current crop of flash MP3 players seem to use a single
alkaline or NiMH AAA cell.

OTOH, Maxim shows a wide range of converters with inputs as
low as 0.6 volts and plenty rated at 1.5 volt input. A wide
range of output voltages is listed as well.

http://para.maxim-ic.com/compare.asp?Fam=DCDC_All&Tree=PowerSupplies&HP=PowerSupplies.cfm&ln=&SORD=1751&FT_1751=21300&ITEMLIST=15C03,15C04,15C05,15C06,15C09,15C0A,15C1A,15C1B,15C26,15C27,15C28,15C2A,15C33,15C34,15C37,15C38,15C39,15C3A,15C3B,15C3C,15C53,15C56,15C57,15C5C,15C5E,15C5F,15C60,15C68,15C69,15C6A,15C6B,15C82,15C83,15C84,15C89,15C8A,15C8B,15C93,15C94,15C99,15CA9,15CAA,15CAB,15CAC,15CB2,15CBA,15CBB,15CBF,15CC0,15CC3,15CC4,15CCC,15CCD,15CCE,15CCF,15CE9,15CEA,15CEF,15CF0,15CF1,15CF2,15CF8,15CF9,15D07,15D08,15D0D,15D0E,15D0F,15D10,15D11,15D12,15D13,15D1A,15D1B,15D1C,15D1D,15D1E,15D34,15D46,15D47,15D48,15D5F,15D67,15D68,15D69,15D86,15D87,15D92,15D97,15DAE,15DAF,15DB0,15DB1,15DB2,15DB3,15DB4,15DB9,15DBA,15DBB,15DBC,15DBD,15DC0

On a volume basis, the AA cell comes out ahead by 4:1. If
you more
realistically use a box (rectangular prism) that just
encloses the AA
cylinder for the occupied volume, it's still ahead by more
than 3:1.

It looks like the DC-DC converter could be packaged so it
had about 1/6 the volume of a 9 volt battery.

Chances are you're going to use a switching regulator anyway if you
want good battery life. Otherwise you're probably throwing away more
than half the energy.

All things considered the 2-AA cell solution is still ahead
by something like 2:1 in terms of power per volume, but at a
significant cost in terms of minimum size and cost.

It's probably the cost that dominates most design decisions
for consumer products. A DC-DC converter could add $20-30 to
the final cost.

It's a complex comparison-- case size, styling, and battery life and
often charger considerations have to be taken into account in a
portable product. I don't know how much the newest small stepup
converters cost in consumer production volume, but mature SMPS chips
are in the 10 to 20-cent range. The newest ones could be 5 or 10 times
that, even in volume.

The size of things like digital cameras, games etc. have decreased to
the point where they often insist on newer types of batteries. These
things are expensive to replace, and you can't take advantage of
improvements in technology. My first digital camera took 4 AA cells,
and I now use 2450mAh batteries in it. The first ones were 1300mAh.
That's a considerable improvement (over 6 years). My more recent
purchases use special Li-ion batteries. At least one company is
pushing security chips to prevent the use of third-party battery packs
in new designs. Li-ion cells also need a more sophisticated charger
technology AFAIUI.

But compare a typical Li-ion cell-

3.7V output. 5.5mm x 34mm x 50.4mm and only 21 grams. 860mAh at 3.7V.
That's almost half the thickness of a AAA cell and has about the
energy storage capacity and voltage output of 3 typical AAA cells.
Very tempting.

It seems like a single-AA cell solution could be practical
for higher end wireless mics and earphones for pro audio,
for example.

Yes, I would think it would be good. Or even a AAA*.
But the little flat Li-ion batteries would be even sleeker.

* pronounced "triple-A", hence the "a".



Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com