Amplifier Utilities.............

[Jack_Hester]

I haven't had much of an amp building/repairing year.  Work has been good.  But, my free time is mostly mowing and other chores.  However, I'm able to get in computer time, early mornings and just before bedtime.  Mostly drawings, but conversation with a friend led me down another path. 

Every once in a while, I do a brain lock, and can't see the obvious.  He and I were discussing stage gain, and I got all screwed up on the effect of the cathode bias resistor (when used) on the gain of a stage.  Got it all backwards, as a matter of fact.  So after he sent me a couple links to help refocus, I pulled out the RCA manual, and the Radiotron Handbook, and started brushing up.  This led to writing a small program.

I am a hobbyist programmer, in every sense of the term.  I haven't had a need do it for work, in about 20 years.  And then, it was a specialized language called Taylor Control Language.  But because it is very much like Pascal, I learned that language.  I moved over to Delphi, when I had no need for it at work. 

I put my studies down in a simple program, that will grow over time.  I let this do the math that I would otherwise do with a calculator.  I know that there are tons of online calculators.  But, doing this helps me to remember.  Here is the most recent compile of the program:

http://www.terra-glide.net/pgms/AmpUtils.exe

I have a Help screen in the works, to define the variables.  That will be available soon.

Within the program, I've included some of the most common tubes, along with a number of the little 7-pin tubes that I'm presently working with.  For those tubes not available, I've provided 'edit boxes' to enter data.  There are 'Reset' buttons to clear any Radio Buttons, before making manual entries.

Here is a link that I used to model most of the gain calculations:

http://www.aikenamps.com/TechInfo.htm

Here is another link of his that has more equations:

http://www.aikenamps.com/Equations.htm

There are a couple pentodes listed (6AU6/12AU6 and 5879) that I'm unsure if I have the correct data in the coding for those selections.  The triodes seem to work just fine. 

The two cathode follower calculations came out of the RCA RC-22 manual.  Didn't compare them with the RC-30, but they should be the same.  I haven't found any examples to prove these out, so they are still a work in progress.

Give it a try and please comment. 

Jack

[PRR]

Keuhnel has several calculators on his website, for example:

http://www.ampbooks.com/home/amplifier-calculators/12AX7/
{No longer works for IE8!}

[Jack_Hester]

Keuhnel has several calculators on his website, for example:

http://www.ampbooks.com/home/amplifier-calculators/12AX7/
{No longer works for IE8!}

Thank you for the link.  I'll pull out the book and see if he provides the math to go with his curves.  I struggle with xyz curve fitting. 

Jack

[Jack_Hester]

Taylor Control Language, I haven't seen reference to this language in over 10 years.  I saw the language on an X ray fluorescence machine used at a mine I worked at.  (I was in charge of its operation).   

Yep!  The Taylor MOD300 was our boiler controls on four generating Units for about 20 years.  TCL was a means to enhance the Unix-based control system.  I spent more time in the configurator than TCL.  But, it was fun for a younger brain.  It would be fun now, but we have since changed over to Emerson (used to be Westinghouse) Ovation system, a Windows-based system.  Uses AutoCAD to configure and then observe the live operation within the drawing.  Great for troubleshooting.  But, plant personel are not allowed full configuration, as we were back in the MOD300 days.  So, I do it for fun, if nothing else, on my own.

[Davidg]

Thanks Jack! I think this is a great tool to add to the arsenal.I just tried it for a few minutes but the only trouble I hadwas it came up on the edge of my screen and I lost the left hand side of the gain calculator once I put anything in but that may be correctable on my end I just had a few minutes to check it out but will def use it in the future.I have very slow internet connection and this will be much faster for me than pulling up a web calculator,it also seems more intuitive to me than the others I have used.Thanks!

[Jack_Hester]

Sorry about that.  I modified it to center itself on the desktop.  Download it again, and let me know how it works this time.

http://www.terra-glide.net/pgms/AmpUtils.exe

I am unable to spend a lot of time on it.  Over time, it should turn out to be useful.  My little programs come about, because I prefer stand-alone aids, though I really appreciate the resources of the Internet. 

Jack