Amplifier transistor matching?

DIYprojects.info
DIY Guides | DIY Projects | DIY forums, newsgroups

Profile

Amplifier transistor matching?
Goto page Previous 1, 2, 3 ... 9, 10, 11

Index -> Home Audio (rec.audio.tech)

Author

Message

Mr.T
Guest

Posted: Thu Jun 16, 2005 9:02 am Post subject: Re: 9V batteries

"Jonathan Westhues" <google-for-my-name@nospam.com> wrote in message
news:Vj9se.7292$yU.572117@news20.bellglobal.com...

Quote:

"Mr.T" <MrT@home> wrote in message
news:42b114b3$0$16493$afc38c87@news.optusnet.com.au...
Yes I read it, and still say a D cell has more energy per unit volume.
Possibly per unit weight, but I'll let you do the calculation for that
if
you like :-)

I used the alkaline Energizer Industrial series, because Digikey sells
them. All capacities are to 0.8 V per cell, at 25 mA. That puts 9V
batteries at a slight disadvantage, because that is more watts with a 9V
than a 1.5V, but it looks like the error is small enough that I wouldn't
do better trying to read a capacity off the graph.

The prices are in ones. They provide a volume, which appears to be more
or less the volume of the cylinder, but I also calculated the `bounding
box' volume.

AA cell:
m=23 g, Q=2779 mA*h, E=4168 mW*h, $=0.75 CAD, V=8.1 or 9.8 cm^3
E/m = 181, E/V = 515 or 425, E/$ = 5557

D cell:
m=142 g, Q=20500 mA*h, E=30750 mW*h, $=1.69 CAD, V=55.9 or 69.4 cm^3
E/m = 216, E/V = 550 or 443, E/$ = 18195

Thanks for showing that I was right and a D cell does in fact have more
energy per unit volume, and is FAR better in energy per dollar.
Frankly I couldn't be bothered going to the trouble you have, so I'm
impressed you did even though it proves you were wrong.

Quote:

9V battery:
m=45.6 g, Q=625 mA*h, E=5625 mW*h, $=2.86 CAD, V=21.1 cm^3
E/m = 123, E/V = 267, E/$ = 1966

6V lantern battery:
m=665 g, Q=18000 mA*H, E=108000 mW*h, $=13.02 CAD, V=440.4 cm^3
E/m = 162, E/V = 245, E/$ = 8295

The energy figures are wrong because the voltage declines during the
life of the cell, but they will be equally wrong for all types so I
think that the numbers can be compared.

So that means that a AA cell is twice as good as (E/V) or 50% better
than (E/m) a 9V battery. A D cell is about as good as (E/V) or 20%
better than (E/m) a AA cell. That is sort of like what I expected.

Which puzzles me why you claimed otherwise then?

Quote:

What's wrong with the lantern battery though? Is there a good reason why
it's worse or did I make a silly mistake somewhere? Different capacity vs.
internal resistance tradeoff?

They have always been a rip off such that adapters were even made to fit 4 D
cells instead. The E/V is pretty similar to the other rip off, the 9V
battery though.

MrT.

Ken Smith
Guest

Posted: Thu Jun 16, 2005 1:57 pm Post subject: Re: 9V batteries

In article <42b1187d$0$16705$afc38c87@news.optusnet.com.au>,
Mr.T <MrT@home> wrote:
[....]

Quote:

The figures are rather misleading, but you are probably correct this time.

I think the figures are no more misleading than many.

Quote:

Your "I suspect that the cells in the 9V are actually a little better than
the AA in energy per volume" is still doubtful though.

Pry apart a 9V battery and look at how the cell is constructed. There is
very little there that is not the active part of the cell.

--
--
kensmith@rahul.net forging knowledge

Jonathan Westhues
Guest

Posted: Thu Jun 16, 2005 9:04 pm Post subject: Re: 9V batteries

"Mr.T" <MrT@home> wrote in message
news:42b13882$0$13943$afc38c87@news.optusnet.com.au...

Quote:

AA cell:
m=23 g, Q=2779 mA*h, E=4168 mW*h, $=0.75 CAD, V=8.1 or 9.8 cm^3
E/m = 181, E/V = 515 or 425, E/$ = 5557

D cell:
m=142 g, Q=20500 mA*h, E=30750 mW*h, $=1.69 CAD, V=55.9 or 69.4 cm^3
E/m = 216, E/V = 550 or 443, E/$ = 18195

Thanks for showing that I was right and a D cell does in fact have more
energy per unit volume, and is FAR better in energy per dollar.
Frankly I couldn't be bothered going to the trouble you have, so I'm
impressed you did even though it proves you were wrong.

[...]

So that means that a AA cell is twice as good as (E/V) or 50% better
than (E/m) a 9V battery. A D cell is about as good as (E/V) or 20%
better than (E/m) a AA cell. That is sort of like what I expected.

Which puzzles me why you claimed otherwise then?

You may wish to check the From: header. That was my first post to the
thread.

Jonathan

Joerg
Guest

Posted: Thu Jun 16, 2005 10:05 pm Post subject: Re: 9V batteries

Hello Rich,

Quote:

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

Yes, but that would be a kludge. It isn't rocket science to design stuff
so it can work off a couple AA NiMH. What's the big deal?

Regards, Joerg

http://www.analogconsultants.com

Joerg
Guest

Posted: Thu Jun 16, 2005 10:05 pm Post subject: Re: 9V batteries

Hello Arny,

Quote:

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.

You can build your own DC-DC with cheap logic chips and that works just
fine down to 2V.

Also, nearly any function can be achieved with circuitry that works at
2V without a converter. I am glad that Sennheiser has finally done it as
well. Their G2 mics can take two AA NiMH. Way to go. Thing is, if they
hadn't done it we wouldn't have bought their stuff anymore.

Quote:

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.

Nah, the last one I designed was well under a Dollar. Ok, mass
quantities but even with low qties it wouldn't have been a lot more.

Quote:

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

Yes. But it requires that engineers learn to design down to transistor
level again. With opamps it usually isn't going to work without the cost
going through the roof.

Regards, Joerg

http://www.analogconsultants.com

Jim Thompson
Guest

Posted: Thu Jun 16, 2005 10:05 pm Post subject: Re: 9V batteries

On Thu, 16 Jun 2005 21:25:03 GMT, Joerg
<notthisjoergsch@removethispacbell.net> wrote:

[snip]

Quote:

I am glad that Sennheiser has finally done it as
well. Their G2 mics can take two AA NiMH. Way to go. Thing is, if they
hadn't done it we wouldn't have bought their stuff anymore.

[snip]

Joerg
Guest

Posted: Thu Jun 16, 2005 10:05 pm Post subject: Re: 9V batteries

Hello Jim,

Quote:

Joerg, Which G2 model (lapel mike, with receiver) do you recommend?
Thanks!

Don't know yet but I will have to figure that out anyway for our church.
Probably this weekend. When I found out I'll let you know. First I'll
have to find a reasonable dealer (good prices) but that's the easy part.

Regards, Joerg

http://www.analogconsultants.com

Mr.T
Guest

Posted: Fri Jun 17, 2005 6:02 am Post subject: Re: 9V batteries

"Jonathan Westhues" <google-for-my-name@nospam.com> wrote in message
news:Vulse.7613$yU.616660@news20.bellglobal.com...

Quote:

You may wish to check the From: header. That was my first post to the
thread.

My sincere apologies.

MrT.

Tim Martin
Guest

Posted: Mon Jul 18, 2005 1:05 am Post subject: Re: 9V batteries

"Joerg" <notthisjoergsch@removethispacbell.net> wrote in message
news:P6mse.2844$NU5.601@newssvr13.news.prodigy.com...

Quote:

Yes. But it requires that engineers learn to design down to transistor
level again. With opamps it usually isn't going to work without the cost
going through the roof.

By the way, while many op-amp circuits published specify a supply coltage of
+- 15 volts, or +- 9 volts, many circuit designs will work with +- 3 volts,
which is easily achieved with two pairs of AA cells.

Also, many circuits will take more power from one side of the power supply
than the other; so if you're using batteries to provide a +- power supply,
it's worth testing them to see if only half need replacing.

Tim

Watson A.Name - \"Watt Su
Guest

Posted: Mon Jul 18, 2005 5:03 pm Post subject: Re: 9V batteries

"Tim Martin" <tim2718281@ntlworld.com> wrote in message
news:0GCCe.1147$yH4.833@newsfe2-win.ntli.net...

Quote:

"Joerg" <notthisjoergsch@removethispacbell.net> wrote in message
news:P6mse.2844$NU5.601@newssvr13.news.prodigy.com...

Yes. But it requires that engineers learn to design down to
transistor
level again. With opamps it usually isn't going to work without the
cost
going through the roof.

By the way, while many op-amp circuits published specify a supply
coltage of
+- 15 volts, or +- 9 volts, many circuit designs will work with +- 3
volts,
which is easily achieved with two pairs of AA cells.

Also, many circuits will take more power from one side of the power
supply
than the other; so if you're using batteries to provide a +- power
supply,
it's worth testing them to see if only half need replacing.

Tim

I just had to bash the hell out of a mini Maglite to get the innermost
AA cell out of it. It had started to leak and the corrosion on the end
was just enough to prevent it from coming out. I had to smakc it
against a concrete floor, with a few layers of paper towel on it to give
just a small amount of give.

Reason for saying this is that it'e really poor advice to give to reuse
half spent batteries. Works really great if the equipment takes a
single cell. But if you put a half spent battery in series with a new
one, it's likely that the half spent one will be discharged to zero and
beyond, leaking in the process. I think if I had two of four cells run
down faster than the other two, I would swap the sets halfway thru their
life. Better yet, get a piece of equipment that's not so poorly
designed that it runs down one set faster than the other.

jakdedert
Guest

Posted: Wed Jul 20, 2005 1:52 am Post subject: Re: 9V batteries

"Watson A.Name - "Watt Sun, the Dark Remover"" <NOSPAM@dslextreme.com> wrote
in message news:11dnmgl96bnou12@corp.supernews.com...

Quote:

"Tim Martin" <tim2718281@ntlworld.com> wrote in message
news:0GCCe.1147$yH4.833@newsfe2-win.ntli.net...

"Joerg" <notthisjoergsch@removethispacbell.net> wrote in message
news:P6mse.2844$NU5.601@newssvr13.news.prodigy.com...

Yes. But it requires that engineers learn to design down to
transistor
level again. With opamps it usually isn't going to work without the
cost
going through the roof.

By the way, while many op-amp circuits published specify a supply
coltage of
+- 15 volts, or +- 9 volts, many circuit designs will work with +- 3
volts,
which is easily achieved with two pairs of AA cells.

Also, many circuits will take more power from one side of the power
supply
than the other; so if you're using batteries to provide a +- power
supply,
it's worth testing them to see if only half need replacing.

Tim

I just had to bash the hell out of a mini Maglite to get the innermost
AA cell out of it. It had started to leak and the corrosion on the end
was just enough to prevent it from coming out. I had to smakc it
against a concrete floor, with a few layers of paper towel on it to give
just a small amount of give.

Reason for saying this is that it'e really poor advice to give to reuse
half spent batteries. Works really great if the equipment takes a
single cell. But if you put a half spent battery in series with a new
one, it's likely that the half spent one will be discharged to zero and
beyond, leaking in the process. I think if I had two of four cells run
down faster than the other two, I would swap the sets halfway thru their
life. Better yet, get a piece of equipment that's not so poorly
designed that it runs down one set faster than the other.

Measuring and matching used batteries is not that difficult, if you need to
use them in pairs. Also, some sources for used batteries are applications
where they were originally used in pairs. I collect and cull AA's from RF
mics all the time with little ill-effect. Sometimes I come in from a gig
with my pockets literally bulging with AA's. I usually just match them by
open-circuit voltage and put them in different piles matched within a 0.1 or
..05 volts of one another. Anything below 1.4 volts, I usually either
relegate to the kids' CD/Mp3 players or discard.

It saves me hundred$ a year, at least.

jak

Quote:

Tim Martin
Guest

Posted: Sat Jul 23, 2005 3:08 pm Post subject: Re: 9V batteries

"Watson A.Name - "Watt Sun, the Dark Remover""

Quote:

Better yet, get a piece of equipment that's not so poorly
designed that it runs down one set faster than the other.

OK. Suppose we have a circuit that draws 20 milliamps at -3v, and 220
milliamps at +3 volts. And suppose our power supply is four 1.5v 2200mAh
batteries, wired so one pair provides +3v, and the other pair provides -3v.

Is it possible to redesign the power supply to do better than replace the
+3v pair of batteries every 10 hours, and the -3v pair of batteries every
110 hours? (So for 110 hours of operation, we'd need to replace 12 pairs of
batteries.)

Tim

Kristian Ukkonen
Guest

Posted: Sat Jul 23, 2005 5:03 pm Post subject: Re: 9V batteries

Tim Martin wrote:

Quote:

"Watson A.Name - "Watt Sun, the Dark Remover""
Better yet, get a piece of equipment that's not so poorly
designed that it runs down one set faster than the other.

OK. Suppose we have a circuit that draws 20 milliamps at -3v, and 220
milliamps at +3 volts. And suppose our power supply is four 1.5v 2200mAh
batteries, wired so one pair provides +3v, and the other pair provides -3v.

Is it possible to redesign the power supply to do better than replace the
+3v pair of batteries every 10 hours, and the -3v pair of batteries every
110 hours? (So for 110 hours of operation, we'd need to replace 12 pairs of
batteries.)

Make a switching powersupply using 6V input and outputing
two 3V voltages?

Use a latching relay to switch the batteries (3V <> -3V)
every once and a while?

Mr.T
Guest

Posted: Sun Jul 24, 2005 7:02 am Post subject: Re: 9V batteries

"Kristian Ukkonen" <kristian.ukkonen@iki.fi> wrote in message
news:kkuEe.168$Dl5.67@read3.inet.fi...

Quote:

Tim Martin wrote:
"Watson A.Name - "Watt Sun, the Dark Remover""
Better yet, get a piece of equipment that's not so poorly
designed that it runs down one set faster than the other.

OK. Suppose we have a circuit that draws 20 milliamps at -3v, and 220
milliamps at +3 volts. And suppose our power supply is four 1.5v
2200mAh
batteries, wired so one pair provides +3v, and the other pair
provides -3v.

Is it possible to redesign the power supply to do better than replace
the
+3v pair of batteries every 10 hours, and the -3v pair of batteries
every
110 hours? (So for 110 hours of operation, we'd need to replace 12
pairs of
batteries.)

Make a switching powersupply using 6V input and outputing
two 3V voltages?

Use a latching relay to switch the batteries (3V <> -3V)
every once and a while?

Seems like a lot of extra effort and expense for no net benefit.
If you improve the circuit by converting the 6V to +/- 15V instead,
(assuming that does provide some benefit for the circuit involved) at least
there may be some point to it all.
Otherwise it would probably be easier to provide a battery low indicator for
each pair of cells.

MrT.

Watson A.Name - \"Watt Su
Guest

Posted: Sun Jul 24, 2005 8:03 pm Post subject: Re: 9V batteries

"Tim Martin" <tim2718281@ntlworld.com> wrote in message
news:3PsEe.5181$YL5.2604@newsfe2-win.ntli.net...

Quote:

"Watson A.Name - "Watt Sun, the Dark Remover""

Better yet, get a piece of equipment that's not so poorly
designed that it runs down one set faster than the other.

OK. Suppose we have a circuit that draws 20 milliamps at -3v, and 220
milliamps at +3 volts. And suppose our power supply is four 1.5v
2200mAh
batteries, wired so one pair provides +3v, and the other pair
provides -3v.

Is it possible to redesign the power supply to do better than replace
the
+3v pair of batteries every 10 hours, and the -3v pair of batteries
every
110 hours? (So for 110 hours of operation, we'd need to replace 12
pairs of
batteries.)

Tim

I would use a DC-DC converter to get the minus 3V, at 20mA. SHould take
just a 555 and a cap and a couple rectifiers. A V doubler with a zener
seems like it would do the trick.

http://ourworld.compuserve.com/homepages/Bill_Bowden/page10.htm#5volts.g
if
But use a CMOS 555 if the supply is less than 5V. But the CMOS 555 may
not source enough current, I'm not sure how much it can handle.

http://www.mpja.com/productview.asp?product=2308+PS This one is already
assembled.

http://www.build-it-electronics.com/page4.htm It doesn't have to be this
fancy.

http://www.national.com/ms/LB/LB-18.pdf

Display posts from previous:

	Index -> Home Audio (rec.audio.tech)	All times are GMT Goto page Previous 1, 2, 3 ... 9, 10, 11
Page 11 of 11

FAQ

Memberlist

Usergroups

Featured Site: Free Antivirus and Antispyware Info

Powered by p|-|pBB

Usenet and forums posts belong to their respective authors. Everything else is (c) 2004 - 2006 Web-S-Sense Pty. Ltd.
Terms and Conditions of Use