Thanks Ray. Regards.
Max. K 4 O D S. Email: [EMAIL PROTECTED] Transistor site http://www.funwithtransistors.net Vacuum tube site: http://www.funwithtubes.net Music site: http://www.maxsmusicplace.com To subscribe to the fun with tubes group send an email to, [EMAIL PROTECTED] ----- Original Message ----- From: "Ray Boyce" <[EMAIL PROTECTED]> To: <[email protected]> Sent: Sunday, July 01, 2007 5:48 PM Subject: [BlindHandyMan] History of the Zinc Carbon Cell > History of the Zinc-Carbon Cell > > The zinc-carbon cell, or dry cell, is the forefather of today's cells, and > is often called the Leclanche cell after its inventor, Georges Leclanche. > The > original Leclanche cell utilized only one liquid material, an ammonium > chloride solution that replaced the acid electrolyte used in earlier > cells. > A manganese > dioxide and carbon dry mix replaced the depolarizing solution of most > previous cells, and a carbon bar, whose function was both a current > collector and > positive electrode, went down the middle. At its invention, it was > restricted to laboratories due to its liquid content. > > The first dry cell, also a zinc-carbon cell, appeared between 1886 and > 1888, > and was developed by Karl Gassner. At first, the electrolyte was composed > of > a paste made up of zinc oxide, sal ammoniac, and water, and the zinc > negative electrode was also the container for the cell's contents. The > carbon rod > went down the center of the battery, and served as its positive electrode. > Chemistry > > The zinc-carbon cell has a zinc anode, a manganese dioxide cathode, and an > electrolyte of ammonium chloride or zinc chloride, which is dissolved in > water. > For each unit of electrical energy a galvanic cell creates, an equivalent > amount of electrode material salts must move or be altered to provide > energy. > Ammonium chloride and zinc chloride in an aqueous solution combine to form > a > moist mixture: the cathode contains solid ammonium chloride, which acts as > a fuel reserve for the cell during intermittent operation, and materials > such as gum karaya and ion exchange resins may be added to the cathode in > order > to increase the discharge efficiency. In addition, zinc carbon cells > contain > separators up to 3.5 mm thick that are made of cereal paste and > electrolyte > solution, and serve as an electrolyte reservoir as well as a membrane > between the electrodes. > Types of Zinc-Carbon Cells > > Zinc-carbon dry cells are sold in two main classes: cylindrical cells and > flat cells. The cylindrical cells come either singly or with two more in a > battery, > while flat cells are usually sold from four to three hundred or more cells > in a stack or set of stacks. > Construction Details > > Zinc-carbon batteries have a variety of electrode and packaging > materials-- > each material must be of high quality, or the performance of the cell or > its > appearance will be degraded to some extent. Most dry cells combine zinc > with > mercury (less than 1 part per million in modern cells) to significantly > improve > its resistance to corrosion over times. The zinc may contain about 0.05% > cadmium, as the cadmium refines the grain and makes the alloy harder and > also > more corrosion resistant, and may also contain 0.25% lead. Note, cadmium > and > mercury have been banned from most consumer batteries of this type > manufactured > in the United States since 1990 because of environmental concerns > associated > with their disposal. > > The manganese dioxide cathode material is another important component, and > must be very pure. Usually, this compound comes from mines in Mexico, > Gabon, > China, and Brazil, where impurities like nickel, copper, arsenic, and > cobalt > are in small quantities or insoluble. The manganese dioxide is always > mixed > with graphite or acetylene (carbon) black to provide better electrolyte > conductivity and absorption. Usually, only a small amount of graphite is > used, > with the majority of the carbon as acetylene black, because it is a stable > form of finely divided carbon and is highly conductive. > > > > > To listen to the show archives go to link > http://acbradio.org/handyman.html > or > ftp://ftp.acbradio.org/acbradio-archives/handyman/ > > The Pod Cast address for the Blind Handy Man Show is. > http://www.acbradio.org/news/xml/podcast.php?pgm=saturday > > Visit the archives page at the following address > http://www.mail-archive.com/[email protected]/ > > Visit The Blind Handy Man Files Page To Review Contributions From Various > List Members At The Following address: > http://www.jaws-users.com/handyman/ > > If you would like to join the Blind Computing list, then visit the > following address for more information: > http://jaws-users.com/mailman/listinfo/blind-computing_jaws-users.com > > For a complete list of email commands pertaining to the Blind Handy Man > list just send a blank message to: > [EMAIL PROTECTED] > Yahoo! Groups Links > > > > > > > -- > No virus found in this incoming message. > Checked by AVG Free Edition. > Version: 7.5.476 / Virus Database: 269.9.14/880 - Release Date: 6/29/2007 > 2:15 PM >
