Mike, In such cases I apply a variable constant. Happy POETS Day Regards Eric Dawson > -----Original Message----- > From: Mike Fenner [SMTP:[log in to unmask]] > Sent: Friday, October 26, 2001 8:33 AM > To: [log in to unmask] > Subject: Re: [TN] Adjusting the alloy composition in the solderpot > > So using your formula that makes Bev about 150 years old percent then, or > did I miss something. > > Happy Friday. > > Best regards > > Mike > > > -----Original Message----- > From: TechNet [mailto:[log in to unmask]]On Behalf Of Lou Hart > Sent: Thursday, October 25, 2001 5:51 PM > To: [log in to unmask] > Subject: Re: [TN] Adjusting the alloy composition in the solderpot > > > Eric, Steve, et al, > > I recommend going back to basic calculus and calculating the derivative of > fraction tin with respect to weight (mass) of tin. > > Fraction tin = (Tin mass)/(Tin mass + Lead mass) > > You will get (assuming you only want a small change in fraction tin, in > the > range of, say, 0.03 or less) > > Tin add = (Mass of pot) X (change desired in Fraction Tin)/(Fraction Lead) > > On an unrelated matter, let me comment that a number of names like > Shirley, > Beverly, and Vivian were used by men until the first half of the past > century. Over some time period, women largely took possession of them. > Lou Hart > > > > -----Original Message----- > From: Eric Dawson [SMTP:[log in to unmask]] > Sent: Thursday, October 25, 2001 2:53 AM > To: [log in to unmask] > Subject: Re: [TN] Adjusting the alloy composition in the solderpot > > Hi All, > The easiest way to think of this is not the use of a complicated formula, > but the simple application of percentage. > > In the example below, the total weight of tin plus lead is 1500 pounds, > 61.9% of which is tin. Hence there are 928.5 pounds of tin. > Add 45 pounds of tin, the total weight is now 1545 pounds of which, 973.5 > pounds is tin. Work out the new percentage of the new total weight and you > get 63%. > Ahah, I hear you ask, how do you get to 45 pounds in the first place? > Well, > just plug a few numbers into the percentage calculations and see which > direction it takes you. > The main thing to remember is that you add the tin addition to the total > weight as well as the tin content when working out the new percentage. > Hope this helps > Regards > Eric Dawson > > -------------------------------------------------------------------------- > -- > ----- > Technet Mail List provided as a free service by IPC using LISTSERV 1.8d > To unsubscribe, send a message to [log in to unmask] with following text in > the BODY (NOT the subject field): SIGNOFF Technet > To temporarily halt delivery of Technet send the following message: SET > Technet NOMAIL > Search previous postings at: www.ipc.org > On-Line Resources & Databases > > E-mail Archives > Please visit IPC web site (http://www.ipc.org/html/forum.htm) for > additional > information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 > ext.5315 > -------------------------------------------------------------------------- > -- > ----- > > -------------------------------------------------------------------------- > ------- > Technet Mail List provided as a free service by IPC using LISTSERV 1.8d > To unsubscribe, send a message to [log in to unmask] with following text in > the BODY (NOT the subject field): SIGNOFF Technet > To temporarily halt delivery of Technet send the following message: SET > Technet NOMAIL > Search previous postings at: www.ipc.org > On-Line Resources & Databases > > E-mail Archives > Please visit IPC web site (http://www.ipc.org/html/forum.htm) for > additional > information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 > ext.5315 > -------------------------------------------------------------------------- > ------- --------------------------------------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt delivery of Technet send the following message: SET Technet NOMAIL Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------------