EMRFD Message Archive 10992
Message Date From Subject 10992 2015-04-23 21:51:43 Ashhar Farhan using ladbuild for notch filters i was trying to use ladbuild to study some notch filters. i start with a regular ladder type of low pass filter. now, to create the notch i want to add a capacitor across the inductor. how can this be done in ladbuild and gpla?these are the programs that accompany emrfd. i know that these are not full blown programs like the ltspice... but they make very handy tool.s- f 10996 2015-04-24 10:25:09 w7zoi Re: using ladbuild for notch filters Hi Farhan, and the gang,Many thanks for asking about the Ladpac programs. Sorry, but you can't easily get there with the Windows version of Ladpac that comes with EMRFD. The most up to date version is available on my web site (w7zoi.net) in the EMRFD errata section.The old DOS (remember that?) version of LADPAC included code for both a series tuned circuit and a parallel tuned circuit. Both could be used as either series or parallel elements. Hence, things like band stop filters or elliptic low pass filters were easily analyzed. When doing the Windows software I elected not to include these elements, just to keep things simple. That seemed to be the demand at the time. So the present program does not include them. I should probably expand the code to include the traps. I know of one other person who ask about it. (Yea, just one.) Most of my computer activity these days is with a 64 bit laptop that will not run the 32 bit compiler that I used for the EMRFD Windows version of Ladpac.There are other things you can do. First of all, you can write your own program. This takes a while, but it is fun and enlightening. The ladder method that I used for Ladpac is completely described in Intro to RF Design. I believe that you have this book.The Windows version of Ladpac includes crystals, which are just series tuned circuits with a "parasitic" parallel C. Ladpac works just fine with the crystal used as a shunt element. The crystal notch filters that I built for oscillator noise measurement were designed with the Windows version of LADPAC. But there is a hitch: When a circuit in a Windows version of Ladpac includes a crystal, the frequency readout automatically shifts to Hz with respect to the nominal crystal series resonant frequency, which is where the motional L and motional C resonate.If you have a computer kicking around that will run old DOS programs, you can still get the old version of GPLA. Go to the ARRL web site and then look for update info on IRFD. The software that came with that book is found there, including the old MicroSmith. There is no easy way to build a circuit with a program though. You have to build the file in a text editor, load it, and run it. Values can be edited from GPLA though. Instructions are included with the IRFD programs.Any version of SPICE will do the analysis. The schematic editor for LT-SPICE is, as we generally have seen, really outstanding. There are other programs out there that will do the job. Some microwave simulators are really outstanding for such things, and demo versions are available on the web.I'm kinda loaded with projects at the moment. However, I'll put this improvement on the list. Thanks again for asking, and again, sorry that there is not an easy way to use the programs to do what you want to do.73, Wesw7zoi 11001 2015-04-24 13:42:45 Nick Kennedy Re: using ladbuild for notch filters I got really intrigued with the description in IRFD about ten or fifteen years ago and started writing my own ladder network analysis program in Excel using VBA for a lot of it but Excel cell functions for the complex number calculations since there are (or were) none in VBA.I got to the point were it was doing some pretty nice plots and even included crystals as components, holder capacitance and all.But Microsoft was apparently getting highly concerned about malware embedded in VBA code and seemed to be moving away from it so I though my spreadsheet's days were numbered. However these days with current Office software, it does work just fine.The data entry method is a little clunky. It's described in a separate text file which is also contained in a tab of the spreadsheet.The spreadsheet is linked at the bottom of my table of projects on my web page (which I just messed up big time editing it with Word). It's Ladder.ZIP. The zip contains only the one Excel file.May require some of the Add-Ins to be selected in Excel, such as VBA - if that's not standard now.73-Nick, WA5BDU"There are other things you can do. First of all, you can write your own program. This takes a while, but it is fun and enlightening. The ladder method that I used for Ladpac is completely described in Intro to RF Design. I believe that you have this book. " 11013 2015-04-27 23:08:30 Ashhar Farhan Re: using ladbuild for notch filters wes, nick,thanks for the detailed note, wes. Each time, I am amazed at the breadth of the things in these two books. I think I have complained enough in my earlier posts about the lack of mention of these are tools in regular radio work. I have switched to using the LT-SPICE for more involved work but the simplicity of LADBUILD and GPLA is too enticing to fire up the bulky LT-SPICE. So, your decision to keep those features away was not misplaced at all.Often, in software products business, we are constantly reminded that what makes a product great is not what it does but what all it chooses not to do. It must, in the words of knuth, 'perform its intended task unerringly without any side-effects'. which is not unlike what we do with our own homebrews, we take bells and whistles out until we are left with just the bare system that we can apply ourselves to improve.I am using the new spectrum analyzer in the lab based on the Hayward/White design. It is easy life : design with the EMRFD tools and measure it on the specan. It has entirely changed the perspective of looking into a circuit. I find myself using the scope less and less. I will post the details on the website soon.-f 11016 2015-04-28 06:57:01 n.a.moseley Re: using ladbuild for notch filters On 24-4-2015 19:25, firstname.lastname@example.org [emrfd] wrote:
Hi Farhan, and the gang,
If you have a computer kicking around that will run old DOS programs, you can still get the old version of GPLA. Go to the ARRL web site and then look for update info on IRFD. The software that came with that book is found there, including the old MicroSmith. There is no easy way to build a circuit with a program though. You have to build the file in a text editor, load it, and run it. Values can be edited from GPLA though. Instructions are included with the IRFD programs.
Hi Wes, Farhan, all,
I just checked; the DOS version of GPLA and MicroSmith etc will run fine on recent versions of windows using DOSBox.
You can get DOSBox for free at: http://www.dosbox.com/
DOSBox provides a DOS environment and you have to use the DOS commands 'CD' and 'DIR' and to get around its file system.
The built-in MOUNT command allows mounting (parts) of the windows filesystem into DOSBOX as a drive letter.
For example: MOUNT F C:\Users\windows_user\Desktop\test
DOSBOX reads the filenames when mounting, so any file that is added to that location after mounting will not appear when using the DIR command. However, the file is there and can be executed if it is a program, you just won't see it. It's a small nuisance.