HOMEBREW Digest #2722 Mon 25 May 1998

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		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

  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 at burp.org). NOTE NEW HOMEBREW ADDRESS: hbd.org Send articles for __publication_only__ to post@hbd.org (Articles are published in the order they are received.) If your e-mail account is being deleted, please unsubscribe first!! To SUBSCRIBE or UNSUBSCRIBE send an e-mail message with the word "subscribe" or "unsubscribe" to request@hbd.org. **SUBSCRIBE AND UNSUBSCRIBE REQUESTS MUST BE SENT FROM THE E-MAIL **ACCOUNT YOU WISH TO HAVE SUBSCRIBED OR UNSUBSCRIBED!!! IF YOU HAVE SPAM-PROOFED your e-mail address, the autoresponder and the SUBSCRIBE/UNSUBSCRIBE commands will fail! For "Cat's Meow" information, send mail to brewery at hbd.org Homebrew Digest Information on the Web: http://hbd.org Requests for back issues will be ignored. Back issues are available via: Anonymous ftp from... ftp://hbd.org/pub/hbd/digests ftp://ftp.stanford.edu/pub/clubs/homebrew/beer AFS users can find it under... /afs/ir.stanford.edu/ftp/pub/clubs/homebrew/beer JANITORS on duty: Pat Babcock and Karl Lutzen (janitor@hbd.org)
---------------------------------------------------------------------- Date: Sat, 23 May 1998 16:54:22 +1000 (EST) From: Jon Bovard <j.bovard at 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 *$&#( at *'s? Many thanks Jon In Brisbane "Beer, is there anything you cant do" Homer Simpson.. Return to table of contents
Date: 23 May 98 01:04:59 MDT (Sat) From: rcd at 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 at talisman.com Hygiene, Colorado USA ...Mr. Natural says, "Use the right tool for the job." Return to table of contents
Date: Sat, 23 May 1998 00:32:11 -0700 From: Jeremy York <jeremy at 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 at ThemeMedia.com Return to table of contents
Date: Sat, 23 May 1998 11:19:07 +0200 From: Erik =?iso-8859-1?Q?R=F6nnqvist?= <rq at 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 at lysator.liu.se, talk: erik at f90.ryd.student.liu.se http://f90.ryd.student.liu.se |---------------------------------------------------------------------| | Erik Rnnqvist, Studerande och hembryggare | | Telefon: 013-174314, eller 0707-142127 | | rq at lysator.liu.se, eriro948 at student.liu.se, hembryggt at hotmail.com | | talk: erik at f90.ryd.student.liu.se ICQ: 6259670 | | http://f90.ryd.student.liu.se | |---------------------------------------------------------------------| Return to table of contents
Date: Sat, 23 May 1998 14:45:32 +0000 From: "Dr. Pivo" <irv at 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 Return to table of contents
Date: Sat, 23 May 1998 09:30:03 -0400 From: haafbrau1 at 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 at juno.com _____________________________________________________________________ You don't need to buy Internet access to use free Internet e-mail. Get completely free e-mail from Juno at http://www.juno.com Or call Juno at (800) 654-JUNO [654-5866] Return to table of contents
Date: Sun, 24 May 1998 00:19:04 +1100 From: Brad McMahon <brad at 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 at sa.apana.org.au PGP Return to table of contents
Date: Sun, 24 May 1998 00:28:30 +1100 From: Brad McMahon <brad at 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 at sa.apana.org.au PGP Return to table of contents
Date: Sat, 23 May 1998 10:41:34 -0400 From: Jeff Renner <nerenner at umich.edu> Subject: Re: any recipe suggestions for spent grain? Stephanie Deter <stevi at 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 at umich.edu "One never knows, do one?" Fats Waller, American Musician, 1904-1943. Return to table of contents
Date: Sat, 23 May 1998 10:49:40 -0400 From: Jeff Renner <nerenner at umich.edu> Subject: Re: Home Malting "J.Kish" <jjkish at 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 at umich.edu "One never knows, do one?" Fats Waller, American Musician, 1904-1943. Return to table of contents
Date: Sat, 23 May 1998 11:16:04 -0500 From: rlabor at lsumc.edu (LaBorde, Ronald) Subject: RE: Theory and experiment of RIMS and induction heating. From: "S. Wesley" <Wesley at 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 at lsumc.edu Return to table of contents
Date: Sat, 23 May 1998 12:15:04 -0700 From: "Michael Kowalczyk" <mikekowal at 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 Return to table of contents
Date: Sat, 23 May 1998 18:49:18 EDT From: KennyEddy <KennyEddy at 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 at aol.com http://members.aol.com/kennyeddy Return to table of contents
Date: Sat, 23 May 98 18:15:01 EST From: nousers at earthlink.net Subject: The Affordable Dental Plan <A HREF=""> 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 is not html capable: Return to table of contents
Date: Sat, 23 May 1998 22:20:01 -0400 From: dbgrowler at 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 _____________________________________________________________________ You don't need to buy Internet access to use free Internet e-mail. Get completely free e-mail from Juno at http://www.juno.com Or call Juno at (800) 654-JUNO [654-5866] Return to table of contents
Date: Sun, 24 May 1998 08:23:34 -0400 From: "Frederick L. Pauly" <flp2m at 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 Return to table of contents
Date: Sun, 24 May 98 09:51:23 PDT From: "George De Piro" <gdepiro at 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. Return to table of contents
Date: Sun, 24 May 1998 08:26:59 -0500 From: Jim Wallace <jwallace at crocker.com> Subject: Re: Evaporation Rates ..................From: Andy Milder <milder at 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 at 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 at crocker.com http://www.crocker.com/~jwallace ___________________________________________ Return to table of contents
Date: Sun, 24 May 1998 22:06:54 -0400 From: "Susan B. Wesley" <wesley at 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 Return to table of contents
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