 |
 | Home | Contact Us | FAQ | Search & Site Map | Link to Us |
 | Sign In | Join | Other 45 Sites in Network |
| HomeDiscussion GroupsElectronicsBasicsRepairDesignCADComponentsEquipmentElectrical Engineering ElectronicsKB.com Contact UsLink To UsSearch & Site Map |
Electronics Forum / Electronics / January 2006BestPair II Voltage Divider Resistor Pair Picker Software
Hi, There are 480,000 different combinations of standard 1% resistor values. If you need 2.75 volts from a 5.00 volt reference, which of those 480,000 pairs will give you the closest result? For this example there are 9 resistor pairs that will get you to within 0.5%, but one resistor pair will get you within 0.15%. Only 1 out of 480,000 combinations is the best pair!! BestPair has been upgraded to Best Pair II. If you are interested you can get it with instant download delivery here --> http://www.velotec.com/BestPair.htm Thanks for looking. Cheers, Tim > Hi, > There are 480,000 different combinations of standard 1% resistor values. If [quoted text clipped - 10 lines] > > Thanks for looking. Thanks for having a look at my app doing the same for free : http://www.ibrtses.com/products http://www.ibrtses.com/products/teiler22.zip Rene  SignatureIng.Buero R.Tschaggelar - http://www.ibrtses.com & commercial newsgroups - http://www.talkto.net >> BestPair has been upgraded to Best Pair II. If you are interested you can >> get it with instant download delivery here --> [quoted text clipped - 9 lines] > > Rene How about my silly javascript version: http://home.comcast.net/~rcmonsen/resistors.html No download required at all... SignatureRegards, Bob Monsen "I cannot persuade myself that a beneficent and omnipotent God would have designedly created parasitic wasps with the express intention of their feeding within the living bodies of Caterpillars" -- Charles Darwin >>> BestPair has been upgraded to Best Pair II. If you are interested you >>> can get it with instant download delivery here --> [quoted text clipped - 14 lines] > > No download required at all... Laydeeze and Gennelmun, I believe we have us a weiner! ;-D Cheers! Rich > >>> BestPair has been upgraded to Best Pair II. If you are interested you > >>> can get it with instant download delivery here --> [quoted text clipped - 19 lines] > Cheers! > Rich Cool, but I often find I havnt got a full set of resistors and so if I want to make a divider thats more exact than i can make with any 2 of the ones I have I have to fiddle about trying to work out what set of 3 resistors that I do have in series/parallel whatever combination will give the best result. (I realy must get some 9k resistors, I so often want to make a 10x non inverting op amp gain stage) Colin =^.^= > Hi, > There are 480,000 different combinations of standard 1% resistor values. If [quoted text clipped - 8 lines] > get it with instant download delivery here --> > http://www.velotec.com/BestPair.htm There are several problems with this. 1. YOu can not be sure of getting .5 % or less error if you have 2 of the 1 % resistors to start with. 2. You did not list the resistance of the source and load. If the source will not supply the needed current for low values, they are out. If you have a low resistance load , the resistors will have to be on the low end of the standard values. > Hi, > There are 480,000 different combinations of standard 1% resistor values. If [quoted text clipped - 13 lines] > Cheers, > Tim I'd like to know what a 2K74 or a 976R resistor is? I noticed this stuff appearing on application notes a while back, what's it all about? DNA > I'd like to know what a 2K74 or a 976R resistor is? > > I noticed this stuff appearing on application notes a while back, what's it > all about? To get rid of fly speck periods in parts values, they use the multiplier (K, M) to represent the decimal point. If the multiplier is 1, they use R. > > I'd like to know what a 2K74 or a 976R resistor is? > > [quoted text clipped - 4 lines] > multiplier (K, M) to represent the decimal point. If the multiplier > is 1, they use R. Yus.... I wasn't really on about that but I think it is a monster brilliant way of doing things. I was on about the idea of a 2K74 or 976R resistor versus 2K7 and 1K. Like the numbers imply 0%1 (snicker) resistors what no-one is going to specify in a design but they appear in application notes in places where no-one would specify them. Cheers DNA > "John Popelish" <jpopelish@rica.net> wrote in message >> [quoted text clipped - 16 lines] > in a design but they appear in application notes in places where no-one > would specify them. I think there are a couple of reasons for the three-digit value. One, in a 1% resistor, you have to have the next value within 1%, right? (or 2, or 0.5, or whatever - that's not the point). As for why such a tight tolerance, there are probably real engineers who do take resistor values into consideration when they're designing something, but, you know, now that I think about it, maybe it's an evolutionary thing. Maybe the resistor manufacturers' process started turning out batches that were so close to each other, so reliably, that they found they could characterize a whole batch within 1%, and then they started dicking around with their process, and found that they could reliably make a batch of _any value they want in the world_ to better than 1% tolerance, so all of the resistor manufacturers had a powwow, and said, "OK, so what values should we assign?" And they came up with that familiar 1% table. Why design engineers use them, well, I could only speculate, other than that the value might make a difference, and when they're cheaper than carbon, they're the logical choice, so you just pick something. ;-) Cheers! Rich > > "John Popelish" <jpopelish@rica.net> wrote in message > >> [quoted text clipped - 37 lines] > Cheers! > Rich You am obvo'ously drunk coz you did not notice the 0%1 reference. Anyway I now have my webserver in the attic up and running wiv Slackware and Apache so I have to say thank you for the whatever. It is..... nice. Now I have to figure out how to ask a question in SED about slowing fans down so's I can get some sleep, because I sleep in the attic. Obsly I need a gmail account and have to do it through google grupes but I don't know how to word my request such that JT will desine one for me. My anti-spam MAF-ID is lorycfn w389065n- 5- C6M35FQG7NMBW Cheers DNA >> "John Popelish" <jpopelish@rica.net> wrote in message >>> [quoted text clipped - 37 lines] > Cheers! > Rich Along about 20 years ago several resister manufacturers were able to produce 1% resisters cheaply and the 1% standard values were already set. The military and instrument manufacturers were already pushing for 0.1% devices. Small wonder that 1% and 0.1% parts are available cheaply now, all the patents have run out. SignatureJosephKK > I was on about the idea of a 2K74 or 976R resistor versus 2K7 and 1K. Like > the numbers imply 0%1 (snicker) resistors what no-one is going to specify > in > a design but they appear in application notes in places where no-one would > specify them. 2K74 is a standard value for 2% tolerance or better resistors (EIA preferred value for the E48 or higher range) 976R is a standard value for 1% or better resistors (EIA 96 or higher range). These values were derived by choosing a set of values whereby the bands of resistance given by the nominal value +/- the tolerances just overlap, giving 6, 12, 24, 48, 96, or 192 values per decade (e.g. between 100 Ohms and 1K) for E6, E12, E24, E48, E96 and E192 ranges respectively. E96 is pretty common now as it makes sense for 1% resistors. E192 is used for tighter than 1% tolerances. Cheers, Alf |
Reply to this Message |
 Sign In
 Join
 My Latest Posts My Monitored Threads My Blog My Photo Gallery My Profile My Homepage Start New Thread Enable EMail Alerts Rate this Thread
|
©2009 Advenet LLC Privacy Policy - Terms of Use
This website includes both content owned or controlled by Advenet as well as content owned or controlled by third parties.