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HOMEBREW Digest #2722
HOMEBREW Digest #2722 Mon 25 May 1998
FORUM ON BEER, HOMEBREWING, AND RELATED ISSUES
Digest Janitor: janitor@hbd.org
Many thanks to the Observer & Eccentric Newspapers of
Livonia, Michigan for sponsoring the Homebrew Digest.
URL: http://www.oeonline.com
Contents:
Weavils from hell... (Jon Bovard)
rhubarb (Dick Dunn)
Spent grain recipe suggestion (Jeremy York)
Lead in brass (Erik =?iso-8859-1?Q?R=F6nnqvist?=)
Airlocks (do you needs them?) ("Dr. Pivo")
Alternate yeast question (haafbrau1)
starting aeration (Brad McMahon)
Hop Rhizomes cont. (Brad McMahon)
Re: any recipe suggestions for spent grain? (Jeff Renner)
Re: Home Malting (Jeff Renner)
RE: Theory and experiment of RIMS and induction heating. (LaBorde, Ronald)
So what's the deal? / Lager Malts for ale. / chest freezer temps. ("Michael Kowalczyk")
Converting Extract to All-Grain (KennyEddy)
The Affordable Dental Plan (nousers)
bread from grist (michael w bardallis)
simple grain test ? ("Frederick L. Pauly")
AHA NHC comments / YEast growth, aeration, etc. ("George De Piro")
Re: Evaporation Rates (Jim Wallace)
Further comments on induction heating ("Susan B. Wesley")
BURP's Spirit of Free Beer competition is June 6-7 and entry information
is available by contacting Jay Adams (adams@burp.org).
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----------------------------------------------------------------------
Date: Sat, 23 May 1998 16:54:22 +1000 (EST)
From: Jon Bovard <j.bovard@student.qut.edu.au>
Subject: Weavils from hell...
Those little black insects that brewers love to hate have taken a liking
to my malts. Big DOH!!
I have heard many opinions as to the effects of these little blighters
ranging from "They will destroy your malt and make foul tasting
beers"(Charlie Papazian), to an older German master-brewer who tells me
"they wont make a lick of difference".
Obviously removing them is next to impossible, even with Co2 injection
into the grain etc there will always be eggs...
I dont bother sifting the grain, I just use it and take great satisfaction
in watching them die a painful death in the hot mash HAHAHA!
Does anyone have any insight into the detrimental affects and degradation
processes of these little *$&#(@*'s?
Many thanks
Jon In Brisbane
"Beer, is there anything you cant do" Homer Simpson..
------------------------------
Date: 23 May 98 01:04:59 MDT (Sat)
From: rcd@raven.talisman.com (Dick Dunn)
Subject: rhubarb
Rhubarb in beer? Why...just to make a point?
Go for mead. Try a strawberry-rhubarb melomel. Finish it as sparkling/
dry. Wonderful.
- ---
Dick Dunn rcd@talisman.com Hygiene, Colorado USA
...Mr. Natural says, "Use the right tool for the job."
------------------------------
Date: Sat, 23 May 1998 00:32:11 -0700
From: Jeremy York <jeremy@ThemeMedia.com>
Subject: Spent grain recipe suggestion
I posted this just last week to rec.crafts.brewing:
I've been using some spent grain in this bread machine recipe
(in my "2 lb" large West Bend bread machine):
3.5 tbs oil
3.5 tbs honey
4-5 tbs spent grain
1 cup water less a tbs or so (adjusting for water in grain)
1 egg (or 1/4 cup water + 2 tbs dried no-cholesteral egg product)
1.25 cups whole wheat flour
2 cups unbleached white flour
1.5 tsp salt
2 tbs wheat gluten
2 tablespoons powdered milk or powdered buttermilk
2.5 tsp yeast
The recipe is modified from one in "Bread Machine Baking"; all
I did was to substitute the spent grain for some texture ingredients
like wheat germ, steel cut oats, cornmeal, etc.
There's a company locally that markets "spent grain" bread machine
mixes, which kind of puzzles me. As far as I can tell, the spent
grain doesn't contribute much flavor to the bread, just some texture
and fiber. I've been using the stuff because I don't like to see
it go to waste, but it's not so incredible that I'd go spend money
just to get a mix with some drained barley in it.
Hrm, now I'm wondering if some of the yeast collected from
sediment would be any good for making bread...
- --
Jeremy York
jeremy@ThemeMedia.com
------------------------------
Date: Sat, 23 May 1998 11:19:07 +0200
From: Erik =?iso-8859-1?Q?R=F6nnqvist?= <rq@lysator.liu.se>
Subject: Lead in brass
I was searching the HBD archives and came across a couple posts about how
to get rid of the lead in brass. They suggested a 2:1 of mixture of vinegar
and peroxide, and I'll try that. What strength peroxide do I need? I can
get, if I remember correctly, 2% or 10% at the local drugstore, will this
be strong enough to do the trick?
Post or private e-mail.
Thanks in advance
Erik Rnnqvist, brewing in Linkping, Sweden
e-mail: rq@lysator.liu.se, talk: erik@f90.ryd.student.liu.se
http://f90.ryd.student.liu.se
|---------------------------------------------------------------------|
| Erik Rnnqvist, Studerande och hembryggare |
| Telefon: 013-174314, eller 0707-142127 |
| rq@lysator.liu.se, eriro948@student.liu.se, hembryggt@hotmail.com |
| talk: erik@f90.ryd.student.liu.se ICQ: 6259670 |
| http://f90.ryd.student.liu.se |
|---------------------------------------------------------------------|
------------------------------
Date: Sat, 23 May 1998 14:45:32 +0000
From: "Dr. Pivo" <irv@wireworks.se>
Subject: Airlocks (do you needs them?)
Boy have I been dumb..... again.
I've been fiddling with airlocks. The results are pretty preliminary,
but it's starting to look like you don't need them.
It may be of particular interest for those worried about oxygen
permeability in plastic, and if it has any significant effects.
I've written it up at...
http://www.magma.ca/~bodnsatz/brew/columns/jirvine/watertrap.html
Guess what? I found the "spell checker" on this one, whilst in the
middle of a "bacon, lettuce, and tomatoe" sandwich.
Dr. Pivo
------------------------------
Date: Sat, 23 May 1998 09:30:03 -0400
From: haafbrau1@juno.com
Subject: Alternate yeast question
Since I only brew ales, I don't think using the bottom sludge would be a
smart move. What is the collective's opinion on drawing 1-2 liters of
actively fermenting wort as a starter for a new batch? Would this work
well? The theory sounds good anyway.
Paul Haaf
haafbrau1@juno.com
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------------------------------
Date: Sun, 24 May 1998 00:19:04 +1100
From: Brad McMahon <brad@sa.apana.org.au>
Subject: starting aeration
Andy wrote:
>One of the most important "by products" (to us beer pigs, not to the
>yeast) of yeast growth is ethanol (ethanol = "bug piss" in local
> slang). Don't want that stuff in our beer do we?
What? I certainly look for ethanol in my beer.
Actually, I'm tried to read that line as sarcastic, but
I'm not sure. Maybe a smiley next time! :-)
Bug piss? Must be a Sydney thing...
- --
Brad McMahon Adelaide, South Australia
brad@sa.apana.org.au
PGP
------------------------------
Date: Sun, 24 May 1998 00:28:30 +1100
From: Brad McMahon <brad@sa.apana.org.au>
Subject: Hop Rhizomes cont.
I should state that
they are under "import control" in Australia.
Contact either
The Imported Food Inspection Service
(02) 62725027
or Australian Quarantine and Inspection Service
(02) 6272 3933
- --
Brad McMahon Adelaide, South Australia
brad@sa.apana.org.au
PGP
------------------------------
Date: Sat, 23 May 1998 10:41:34 -0400
From: Jeff Renner <nerenner@umich.edu>
Subject: Re: any recipe suggestions for spent grain?
Stephanie Deter <stevi@frii.com> is looking for a bread recipe for spent
grains.
I wrote an article ("Bread for Brewers") for Zymurgy last year (Spring,
1997, the infamous "Bottle Opener" issue) on this very subject with several
recipe suggestions. Since you're in Boulder, you could probably just
stroll over to AHA and get a copy.
To tell you the truth, though, I usually just compost 'em myself. They're
awfully fibrous and don't have a lot of flavor or sweetness. But don't run
them down the disposal! Even if you don't compost, they make a good much
around flower beds and whatnot. Don't pile them too thick, though, or they
will really stink.
Jeff
-=-=-=-=-
Jeff Renner in Ann Arbor, Michigan c/o nerenner@umich.edu
"One never knows, do one?" Fats Waller, American Musician, 1904-1943.
------------------------------
Date: Sat, 23 May 1998 10:49:40 -0400
From: Jeff Renner <nerenner@umich.edu>
Subject: Re: Home Malting
"J.Kish" <jjkish@worldnet.att.net> writes, regarding home malting:
>Some people have tried feed barley, but the quality of
>that leaves much to be desired.
As one who has malted feed barley, I'd say that it leaves *something* to be
desired, not much. It works well enough, you just don't get as uniform
sprouting or modification. George DePiro's posted procedure is good. I
dry the malt in a half full sturdy cloth bag tied securely shut in the
clothes dryer with good results, but once a small hole developed in the bag
and the spousal unit was very unhappy.
Jeff
-=-=-=-=-
Jeff Renner in Ann Arbor, Michigan c/o nerenner@umich.edu
"One never knows, do one?" Fats Waller, American Musician, 1904-1943.
------------------------------
Date: Sat, 23 May 1998 11:16:04 -0500
From: rlabor@lsumc.edu (LaBorde, Ronald)
Subject: RE: Theory and experiment of RIMS and induction heating.
From: "S. Wesley" <Wesley@maine.maine.edu>
>I came across a demonstration induction coil. These this
>is basically a coil of about 16 gauge wire mounted in a stand with an
>iron core. It is about 8 inches long and has an inside diameter of 1.5
>inches. It is wrapped about four or five layers deep and usually it
runs
>off 120 VAC. It can be used for lots of fun demos such as lighting a
>light bulb attached to a coil....
Great! Think about what you have accomplished. What is a light bulb?
It is a piece of resistive metal conductor that gets hot. You have a
pilot demonstration and proof of the theory. All that remains is the
scale of the design.
>I removed the core.....
Booommmp - major mistake here. The induction coil was designed with the
core in mind.
If I took a transformer and cut away the core, then, 'smoke gets in your
eyes'.
>The coil was too hot to
>touch and the temperature of the water was only a few degrees warmer.
It
>appears that the vast majority of the power was deposited in the coil
and
>not in the pipe or the water.
That's right, you have removed the iron core, the common flux gathering
and coupling mechanism.
>I then allowed the coil to cool down and
>repeated the experiment with a 1.0" glass graduated cylinder filled
with
>water and not surprisingly the rise in temperature was very small.
Forget about trying to induce a magnetic field in the water itself, the
magnetic lines of force must vary across an electric conducting
material, and water is a poor conductor.
Ron
Ronald La Borde - Metairie, Louisiana - rlabor@lsumc.edu
------------------------------
Date: Sat, 23 May 1998 12:15:04 -0700
From: "Michael Kowalczyk" <mikekowal@megsinet.net>
Subject: So what's the deal? / Lager Malts for ale. / chest freezer temps.
I brewed last night and after 12 hours the airlock hasn't budged. I
repitched from the primary of a previous batch. The beer was in the primary
for 27 days. The yeast was harvested 26 hours before re-pitching, stored in
a mason jar, and kept at 63 degrees. I pitched it into 65 degree wort (
gravity 1.062) that was aerated by spraying the wort into the carboy and
shaking for an additional 10 minutes. Yeast was 1056 American Ale yeast.
Usually when I use this method I get airlock activity in 1-3 hours. So far
nothing.
I think my problems might be:
1. The yeast went dormant sitting in the carboy for a month. Next time use a
quart starter 12 hours before to get the yeast going, but I'm not sure it's
necessary.
2. I'm using my new chest freezer and figure I'll keep the temps at 63
degrees. This way when fermentation starts, it'll bring up the temp in the
carboy to 68 degrees while the ambient temps are 63. Anyway, it could be
that the yeast is having a hard time starting at 63 degrees.
What do you think? I'm leaning towards poor yeast maintenance.
- ------------------------------
I've been using DWC Pilsen malt lot # 305107 for my ales. My ales have been
turning out well for dark beers, but the lighter ones are a little too sweet.
A friend suggested that Lager malts for ales can cause too much diacetyl.
It tastes sweet, not buttery, so I'm inclined to think it's not diacetyl that
I'm tasting.
I've been mashing at 156 degrees for my sacc rest and think this may be the
problem. So last night I mashed at 151 to get a more fermentable wort. I
figure the beer will be (if it ever starts..) a little drier and less sweet.
I have a great experiment going. I mashed 12 gallons and split it into 2
pots. Used different yeasts (Weast 1968 and Wyeast 1056), and different hops
to get a British style ale and an American style ale. So when they both are
ready, I can see if Yeasts have anything to do with how sweet it tastes.
Anyways, what are the drawbacks to using this malt for Ales? I still have 40
pounds of it, so If I shouldn't be using it I'll switch to lagers.
- ------------------------------
To the people who use chest freezers: See above #2 for my rationale on what
temp to keep my freezer for ales. Is my thinking OK? What are your
experiences?
- Mike from Chicago
------------------------------
Date: Sat, 23 May 1998 18:49:18 EDT
From: KennyEddy <KennyEddy@aol.com>
Subject: Converting Extract to All-Grain
Alex MacGillivray RN asks:
"I'm wondering if there is a chart out there that helps to convert dry
malt recipes into whole grain recipes. I'm wondering what the ratio of
dry malt to whole grains is. Any thoughts?"
It's a question of ratio of the points per pound per gallon (ppg)
contributions, or how many gravity points one pound contributes to one gallon.
This varies among liquid extracts as well as all-grain worts due to brewhouse
efficiency. However, typical figures for each are:
Dry Malt Extract: 42 ppg
Liquid Malt Extract: 36 ppg
All-Grain Wort: 28 ppg
Using these figures, to convert from DME to all-grain would require 42/28 or
1.5 times as much grain by weight as extract. Converting from LME to grain
would require 36/28 = 1.29 times as much. If you like other ppg numbers, just
substitute them in the above.
The next point however is to be careful about what you're converting. Trying
to convert extract to grain is tricky since you must know what was in the
original extract to have any chance at really emulating it with grain! An
amber-colored extract could contain corn syrup & caramel color, or it could be
2-row + crystal, or it could be pilsner + munich malt. Same goes for dark
extract; the roastiness (if any!!) of dark extract can vary all over the
place. Pale extracts are often recognizable as "pale ale" or "pilsner" and
they usually try to emulate only one type of grain (or beer style), so this
may not be as much as issue.
Your best bet is to study beer styles and design (Ray Daniels' "Designing
Great Beers" is an excellent resource), and make all-grain recipes from
scratch that make sense. If there is something interesting about a particular
extract recipe then yes, by all means, take a stab at it, but there are too
many unknowns in the equation to make it work right every time.
*****
Ken Schwartz
El Paso, TX
KennyEddy@aol.com
http://members.aol.com/kennyeddy
------------------------------
Date: Sat, 23 May 98 18:15:01 EST
From: nousers@earthlink.net
Subject: The Affordable Dental Plan
<A HREF="http://209.84.246.119/opk/dental1.htm">
Click here to get info on a very affordable dental/optical plan </A>
Type or copy and paste the following address into your browser if your email
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------------------------------
Date: Sat, 23 May 1998 22:20:01 -0400
From: dbgrowler@juno.com (michael w bardallis)
Subject: bread from grist
Stephanie asks: Subject: any recipe suggestions for spent grain?
Zymurgy Special Issue 1985 has an article on the subject, and I recall
seeing a treatment of the subject in a more recent issue, but couldn't
find it. I can summarize them by saying, "Take a couple cups of spent
grist, and add them to an otherwise unaltered recipe for bread." A lot of
brewpubs are serving bread made in this way, and it's pretty tasty. Spent
brewing grains, unfortunately, can really only be used as a "minor
adjunct" in breadmaking, since they are a) coarse, and b) lack glutens.
More than a little in the mix, and you've got one crumbly loaf! I've made
quite a bit, though I've lapsed in recent years, and the effect mainly on
texture & color, is quite nice. I'd recommend at least a bit of sugar,
1-3 Tbsp, for browning and flavor; bread made in this way, especially
with darker grists, makes for great toast. If you can't get away with
beer for breakfast, this may provide succor. As you can see, baking
consumption will never be able to keep up with even partial-mash
production; at our house, most of the grist is composted, and ends up as
mulch for the hop garden. Regular great mandalla kinda thing.Mike
BardallisAllen Park, MIThat's all very well in practice; but will it work
in theory? ---Ken Willing
_____________________________________________________________________
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------------------------------
Date: Sun, 24 May 1998 08:23:34 -0400
From: "Frederick L. Pauly" <flp2m@avery.med.virginia.edu>
Subject: simple grain test ?
I bought some Weissheimer pilsner malt, distributed by I.D.
Carlson, and wanted to know what the protein and modification
levels etc were but calling the distributor was no help, they
claimed to have no numbers on the grain.
So I ate a few of the grains and then ate a few grains of the
Breiss two row. The german malt had a bit nicer, cleaner flavor,
but chewed just as easy as the domestic.
Can I take this to mean they are probably both fairly well
modified and since my protein rests for Breiss have not given me
significant changes in my beer that I can single infuse the
german malt with good results?
Thanks in advance,
Rick Pauly
NucMed Tech
Charlottesville,VA
------------------------------
Date: Sun, 24 May 98 09:51:23 PDT
From: "George De Piro" <gdepiro@NOSPAMfcc.net>
Subject: AHA NHC comments / YEast growth, aeration, etc.
Hi all,
Please ignore the carrots...
>
> Dave Houseman defends the AHA NHC, saying:
>
> "but the place to vent about
> the judges isn't the AHA who has nothing to do with the training,
> certification or selection of the judges in the NHC. It's only in the
> second round and the BOS that the AHA's staff even has control of the
> judging assignments."
>
> Dave is correct, but what he also helps dig a slightly deeper hole for
> the AHA. The AHA does control the judging assignements for the second
> round. That is why I was upset with the AHA last year when I got my
> second round scoresheets back. 3 "judges" evaluated my Weizenbier.
> One National judge and two non-BJCP. The beer scored a 38, which I
> thought was fair.
>
> What pissed me off was the complete lack of comments on the score
> sheets. For a beer to score a 38, there has to be something wrong
> with it. These guys were really conserving graphite, and what little
> they did manage to write described a perfect Weizen. So why did I
> only score a 38? How did that help me and my brewing?
>
> If the 3 guys who judged the German wheat beers at last year's NHC 2nd
> round are reading this, your judging skills are in need of some
> improvement. You know who you are. I am especially concerned that
> somebody ranked "National" would do so poor a job.
>
> In this case, it does no good to complain to the BJCP, because two of
> the "judges" aren't in it! Complaining to the AHA will get you
> nowhere.
>
> I still think the biggest problems with the AHA NHC are the following:
>
> 1. Crappy prizes (when considering the cost of entering)
> 2. Ridiculously long lag between the 1st and 2nd round
> 3. Second round in the middle of summer, so you get to do a stability
> test on your beer by shipping it across country in 90F (34C) heat.
>
> I have talked to folks at the AHA about this, several times, to no
> avail. To show that my criticism is actually constructive, I have
> offered them the following suggestions to the above problems:
>
> 1. Include a free AHA membership and entry to the next year's
> conference and/or GABF as part of the prize. Cost to the AOB: almost
> nothing.
>
> 2. Either reduce the lag between the rounds so that the beers aren't
> completely different and stale, or increase the lag and encourage
> brewers to make a fresh batch.
>
> 3. Move the contest (temporally) so that it is not in July!!!
> ----------------------------------------------------------------------
> -------------------------
> Now on to beer stuff:
>
> I am a bit confused about this whole "don't aerate the wort to reduce
> esters and other yeast by-products" thread.
>
> According to Kunze, ester formation is inhibited as long as yeast are
> producing fatty acids and lipids. Yeast produce these compounds
> utilizing oxygen. If you take away the oxygen, you inhibit lipid
> synthesis, and thus allow ester synthesis to occur. So wouldn't you
> want to give the yeast oxygen to keep ester levels low?
>
> Another point that both Kunze and the folks at Siebel make is that
> decreased fermentation temperature increases overall ester production.
> This is the opposite of what most homebrewers believe. Any comments?
>
> Increased temperature does increase yeast growth, which invariably
> increases the production of higher alcohols. Kunze talks about the
> importance of the ratio of higher alcohols to esters, saying that the
> optimum is 1:2.5-3 (this is from Narziss, Brauwelt 45 (1995). Could
> it be that at higher fermentation temperatures the ratio of higher
> alcohols to esters is skewed, giving the impression of a fruitier
> product when in fact esters levels are actually lower than in a
> cold-fermented beer? The cold-fermented beer will have fewer higher
> alcohols.
>
> Just something to ponder, and maybe discuss...
>
> Have fun!
>
> George De Piro (Nyack, NY) If "NOSPAM" is in my address, remove it
> to reply.
------------------------------
Date: Sun, 24 May 1998 08:26:59 -0500
From: Jim Wallace <jwallace@crocker.com>
Subject: Re: Evaporation Rates
..................From: Andy Milder <milder@rs6k1.hep.utexas.edu>
<< So we 5 gal brewers have about 4 times the surface area/volume as a 10
barrel brewer. >>
...........does this mean we can have a 40% evaporation rate ????
...........in a half barrel pot (15gal)... a 5gal or a 10 gal or even a 12
or 15 gal batch would have very similar evap rates since it is a factor of
surface area and heat source
....BUT...
the thermal loading effects (good and bad) would be very different since it
is a factor of volume and heat source
.................From: gjfix@utamat.uta.edu (George J Fix)
<<For most brewing configurations the total evaporation is approximately
proportional to the total thermal loading, and hence it is used as the
indicator. (There are certain exceptions such as found in some poorly
designed kettle vents.)>>
.........It seems to me that there would be a major variation determined by
kettle configuration (surface area to volume) and that there would be a
considerable range here.
......On the hombrew basis there are all sorts of configurations... surface
area/volume, amount of heat applied, venting dynamics, etc. how could we
possibly assume that a 10% evaporation rate across the board would indicate
a certain amount of heat input (thermal loading)?
.........Is there a standard configuration for the industry?... volume to
surface area, venting moving vapors away at x cubic ft/min, etc? if that
was the case I could see a relationship of thermal loading to evap
<< Nevertheless, what is common to all these studies is that too much is
bad.>>
....I can see this but I fail to see the correlation of evap to thermal input.
.....OK! heat shields in place...
___________________________________________
JIM WALLACE ... jwallace@crocker.com
http://www.crocker.com/~jwallace
___________________________________________
------------------------------
Date: Sun, 24 May 1998 22:06:54 -0400
From: "Susan B. Wesley" <wesley@MAINE.MAINE.EDU>
Subject: Further comments on induction heating
Greetings Y'all!
In my last post on this subject I reported on some quick tests and
simple calculations I did to demonstrate that the idea of trying to use
a pipe filled with water as a secondary coil for a transformer will
result in extremely inefficient transfer of energy to the pipe. Today I
would like to discuss a way in which this Idea could be made potentially
workable. Before I do so let me stress at the outset that I do not
reccomend that anyone try to do this because of safety concerns. I am
particularly concerned about the insulation on the wire of the primary
coil which might not hold up well at mashout temperatures. I am
discussing this only because It is an opportunity to discuss some Ideas
about transfromer design which seem to have escaped some of the
obviously well educated people who have commented on this subject so
far.
The tests I performed used a demonstration induction coil which
consists of a coil and a soft iron core. Under normal operating
conditions this apparatus draws 2.0 Amps when connected to a 120 VAC
source. The resistance of the coil is about 1.50 ohms. If this was a DC
circuit one would expect that the coil would draw 90 Amps. The coil has
an impedance (AC Resistance) of 60 ohms because of the self inductance
of the coil. When I did my tests I removed the core and attached a
variac to the input and turned up the variac to around 30 VAC and 15
Amps. How is it possible that I turned down the voltage but got a larger
current? Remember that I removed the core. The self inductance of the
coil depends on the geometry of the coil, but also upon the material
inside the center of the coil. Removing the iron core will drop the
self inductance of the coil by several orders of magnitude (powers of
10). This means that the impedance without the core is essentially the
resistance of the coil. If I had plugged the coil in without using the
variac to reduce the voltage I would have immediately popped the circuit
breaker. Any attempt to construct a primary coil wrapped around a pipe
(without a core) will probably produce a coil with a resistance of a few
ohms at best and will therefore do the same thing.
The solution to this problem is to put an iron core inside the pipe.
This might best be done by mounting a second copper pipe inside the
first one and filling it with soft iron. Using a bundle of iron wire as
opposed to a single bar would reduce losses in the core due to eddy
currents. If you do my back of the envelope calcualation replacing
mu-zero across the area of the core with mu-iron you will see that the
power transfer becomes much much more efficient, and you might even be
able to get the inductive reactance high enough that you wouldn't blow
the breaker. The larger the fraction of the volume of the large pipe you
can fill, the more efficient the process will become.
The moral of the story is that the core of a transformer does more than
just prevent those pesky field lines from sneaking off between the coils
when you aren't looking.
Brew Safe,
Simon
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End of HOMEBREW Digest #2722, 05/25/98
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