Kuehnel, new book: Circuit Simulation

[PRR]

Richard Kuehnel has a new book coming out. I have read a proof copy.

Guitar Amplifier Electronics: Circuit Simulation
https://www.ampbooks.com/mobile/books/simulation/

It is an excellent, and badly needed, romp with circuit simulation, working through basic filters, power supplies, tube amplifiers (clean to dirty), and development of simple and better tube models.

The example simulator is LTspice, which is free, powerful, and has developed a huge following. Kuehnel describes many "tricks" to get answers out of LTspice; they may be in the program documentation but he tells and shows you the ones most useful for our work. However the work is general and his examples adopted well in my antique PSpice.

While the examples run to tubes, the teachings would be valuable for transistors in audio and similar applications because the setups and results are similar.

He also shows step by step how to build the "potentiometer" subcircuit, symbol and math, which is inexplicably left out of many simulators. With a fix for the divide-by-zero math-problem when you turn the pot to the end. (There are many ways to fix this and we tossed a few around.)

This is in context of developing a high power SE amp with full tonestack and an effects loop which is *designed in*, not tacked on. Interface levels and overload control are carefully considered.

The beauty of electronics is that everything can be exactly calculated. The drudgery of electronics is all the calculations. A circuit simulator does this part of the drudgery for you. (What it will NOT do is understand what you really want to know; a brain is still required. Also device models run from good to rough approximations, and it is tedious to derive ALL the parameters for practical devices especially in the corners. Also music waveforms are not simple so for practical reasons we must use simple waves and deduce the action for musical waves.)

Not listed at Amazon at this moment-- getting stuff through Amazon takes time. Watch TubesAndMore.com also: his last book, they had stock before Amazon.

Meanwhile you can order direct from AmpBooks:
https://www.ampbooks.com/mobile/books/buy-now/

Disclosure: Richard put a few bucks for me in the book, enough to cover my time to read and extensively comment, not enough IMHO to buy my opinion.

[shooter]

not enough IMHO to buy my opinion.

pretty sure that price would be pricey 

[DummyLoad]

Disclosure: Richard put a few bucks for me in the book, enough to cover my time to read and extensively comment, not enough IMHO to buy my opinion.

how much? and more importantly, since we're your lab rats - where's our cut?

--disgruntled rat.

[Ritchie200]

I'm just pissed that a brain is still required....  

Jim 

[Willabe]

--disgruntled rat.

 
 

[Willabe]

I'm just pissed that a brain is still required....  

   

[jjasilli]

Ok, fine.  I just bought the book.  Even though I previously stated no more paper books, only ebooks.  I figure I need to go through the Spice learning curve, 'cause I'm not getting enough headaches. 

[shooter]

I need to go through the Spice learning curve

I have spine damage from all the learning curves, AND re-learning curves 

[Willabe]

Ok, fine.  I just bought the book.  Even though I previously stated no more paper books, only ebooks.  I figure I need to go through the Spice learning curve, 'cause I'm not getting enough headaches. 

I have spine damage from all the learning curves, AND re-learning curves 

       

[jjasilli]

First impressions: not for novices.  Book came today; downloaded LTspice to my touchscreen laptop.  Placed a R.  Placing a component is easy. To stop placing that type of component seems impossible; but a youtube tutorial revealed the state secret: press the Escape key, which does not seem to be documented anywhere. Place the 2nd R for a voltage divider.  If I use the Rotate button, the 1st R scrolls off the screen.  I can use my fingers to shrink the screen to find the 1st R.  But to no avail.  I can't figure out how to move a component, or rotate one that's been placed.  So far I'm limited to placing one component, if I'm lucky.

BTW:  if you have a touchscreen, don't touch a component on the screen; it will produce offspring like rabbits, sometimes. EDIT:  press Esc. 


EDIT:  Kuehnel, does mention the Esc key.  Got the V-divider circuit drawn & ran it.  The correct spice directive appears on the schematic.  Above it a blank black screen appears with 1 Hz to 10Khz on the x-axis; but the black box is empty, with no numbers on either side of the y-axis; and no lines on the inside.

[PRR]

> no lines on the inside.

Working blind here: SPICE does not know what node you want to know about. In my old sim I put a special "arrow" on each point I want plotted. I know LTspice has a different trick but I forget. Kuehnel actually does tell you *every* step (as far as I found) but the story is dense and it is easy to miss a bit.

And yes, you need ESC a lot (too much), and it may not work well with finger instead of mouse. (Pspice gives me a pain the elbow because it is so mouse-intensive, moreso than my image-edit program.)

[kagliostro]

Just because we are talking of simulation

http://el34world.com/Forum/index.php?topic=25165.0

Franco

[DummyLoad]

BTW:  if you have a touchscreen, don't touch a component on the screen; it will produce offspring like rabbits, sometimes. EDIT:  press Esc. 

left click mouse button to paste the part then right click mouse button to quit the tool - most CAD apps that's the ESC key.

to rotate a part - press F8 (drag tool shortcut)- hand appears - click hand on part to rotate, then press Ctrl+R, then right click to exit the drag tool.

LT Spice has a shitty editor - always has and why i don't use it.


--pete

[shooter]

most CAD apps

my CAD program is paint 
took me 6hrs on this drawing last night 
the way I see learning curve on new apps If it takes me longer to learn it than what I am using, quit learning n just suffer though 

[jjasilli]

Thanks for the all suggestions.  I'm trying to get more digital all around.  E.g., using Google Maps & Google Earth to digitally scout hunting locations.  But using them & getting map overlays, property boundaries, etc is difficult.  There are pre-packaged programs like Huntstand which do a lot, but not everything.  Kind of like using the Duncan Tonestack Calculator instead of a spice program.

May be this will help other beginners.

I can now place, move & rotate individual components pretty well in LTspice.  Moving groups of components is still a mystery. 


The difference between right clicking vs. left clicking vs. esc. remains confusing; especially on a mouse pad which seems overly touch sensitive.


EDIT: no sooner did I post this, when I scrolled over the 'in Label" on Voltage Source 1.  A red probe-like object appeared.


Anyway, selecting Run, then activating the Probe over the "out Label" produced the result.  I now see that  this is documented in Kuehnel's book, but w/o mention of the Probe icon. N.b.: my version of LTspice was updated yesterday.  I now see that Run is just a mode, not a command.  Once selecting Run, you must click the spot on the schematic where you want the simulation to take place.

[shooter]

Google Maps & Google Earth

I used to use earth when it resided on my computer, I looked for human_less spaces to visit   Now that it's cloud based, skrew it, it's more painful than paint as CAD software 

[Mike_J]

Can anyone use the simulator program to figure out why one 59 Bassman sounded so good but my 5f6a sounds just like all the rest of them. Would like to know if a drifting cap or resistor could improve the tone and if that simulator could figure that out. Of course I never got a chance to make measurements of the special amp. Had an amp sound close to it once but it tried to catch on fire shortly after I said this amp sounds great. Every other time I ever mentioned an amp sounding good my daughter would run into the room with a fire extinguisher.

[jjasilli]

  Don't think a simulator can help.  But you might be able to program a 'bot to run into your room with a fire extinguisher!

[shooter]

it tried to catch on fire

I always ask the Mrs. if the home insurance is paid up before I try anything creative, screw the fire extinguisher   

[1blueheron]

Now that we don't need to do any math, we can just simulate all of it... where is the button or template to simulate a guitar player?  I finally feel like I might have potential!

Interesting stuff.  The next generation has a pile of cool tools at their disposal to further the art.  Let's hope they aren't too lazy to figure out how to use it or we don't get walloped by an EMP first and have to go back to slide rules and carrier pigeons.

[Mike_J]

Don't think a simulator can help.  But you might be able to program a 'bot to run into your room with a fire extinguisher!

Could use a bot now the daughter is in the last semester of her mechanical engineering degree so she is no longer available if I have a mishap.

[Mike_J]

it tried to catch on fire

I always ask the Mrs. if the home insurance is paid up before I try anything creative, screw the fire extinguisher   

Wise. I should add the home insurance paid up status to my amp building procedures.

[jjasilli]

Progress. Can now more easily place components; move and rotate components; and move groups of components. On to the low pass filter simulation!

[Ritchie200]

Sooo...
What you are saying is, if we need something run on Spice just send you the info?  Wow!  What a great guy!


Jim

[shooter]

+1 
he's on the learning curve, should be able to spice out soon 

[jjasilli]

Sooo...
What you are saying is, if we need something run on Spice just send you the info?  Wow!  What a great guy!

Jim

Sure, no problem so long as there's only 1 R & 1 cap.


Just got the low pass filter to work.  Next, the Gibson GA-40T tonestack: 3R's & 2 caps!  Should produce a midscoop.  Duncan TS lookout!

[jjasilli]

Got the GA-40T tonestack sim working.  I'm saving separate files for each of Kuehnel's homework examples.  Getting better at placing and moving components; and editing. 


Minor issues: 
* Getting grid marks by default on ea new schematic.
* Getting vertical and horizontal "marker" lines to show in the Run window.
* Compressing the run window horizontally.  It stretches across the entire width of the screen.  This makes the sim graphs look stretched-out horizontally.

[Willabe]

Well, looks like your going to be the go to guy with problems on this.   

[jjasilli]

PRR & dummyload have been good with sims!  I need to get more digital all around: amp circuit simulation; earth mapping with overlays; guitar & voice recording.

[shooter]

need to get more digital all around

I got the software flow-charted you just need to write the code 
kinda funny, I came here to get AWAY from digital n back to my analog roots 

[PRR]

> Google Maps & Google Earth to digitally scout hunting locations.  ...property boundaries, etc is difficult.

Some towns, like the one north of me, publish tax-maps with property line coordinates.

My town does not post the info in GIS data format. You can squint some maps online but that's not a machine's job.

Google scarfs-up the web-published data, but isn't so good about coming out here and walking the lines. (The G-car has never been on my road; the Bing-car turned IN my driveway which makes it awkward to track Street View.) I know the frontage-stakes on my road, but the depth of the lot is approximate (there's a number in the deed but the reference is unclear).

I suspect only the more urban hunting areas will have property lines. Where property is $1M/acre the taxman is diligent but it may be 1/8-acre lots and not enough room to swing a long-gun. Where property is $100/acre and lots are 1,000 acres, the taxman may just keep rough notes in a ledger.

[jjasilli]

Yeah, I know.  That's why I go hunting.  But digital mapping makes it possible to significantly scout an area in advance.  Topography; tree cover.  With Google Earth you can go back in time - get satellite images in winter.  Hardwood leaves are down; now evergreen stands are obvious.  You can checkout museums and painting exhibits in 3D around the world; or sim off-beat amp circuit ideas in advance of building.


Anyway, in LTspice > Windows > Tile Vertically gives me a good enough graph shape.  Still can't get grid lines to appear on the graph, though they show-up in the dialog box under Tools > Color Preferences.  Que passa?

[jjasilli]

Property lines are available from other map programs or apps, such as Huntstand and Onx.  They also give public land boundaries, private property boundaries; and owners' names maybe for an extra fee.  Then there are mapping apps geared to hiking / camping.  These apps allow the placement on the map of semi-custom marker Icons for Gates, Parking, Buildings, animal sightings, etc.  They can measure distance between points on a line you draw.  Compute the the acreage of boundaries that you draw; and compute the miles around the perimeter, etc. Different overlays may be selected for Street, Satellite, Topographic - overlays are difficult with Google Earth which is free & powerful but a real learning curve.  You can locate yourself on the map on your phone in real time with GPS, and trace your steps as you go.  Place dedicated markers for things you see or do; or for a to do list. 


It no longer makes sense to me to build and measure different amp circuits when they can be modeled in advance.

[shooter]

You can locate yourself on the map

in the early days when Magellan(?) was king of gps I had trained 12 kids on map n compass work, headed for the hills of E. Kty.  I picked a trail - wildcat, let the kids navigate, within a mile I knew we were "off the beaten path" 
as time passed (3-4miles) and they got somewhat anxious, us 4 grown-ups stepped in, my gps couldn't get a satellite link, let alone 3. 6hrs and some dicey environmental obstacles, cliffs, waterfalls.... we popped out a mile from the cars.  As I bump into those "kids" now without exception "It was one of my best moments growing up".
sometimes 'ol skool ain't a bad way to go 

[jjasilli]

Yeah.  A week and a half ago I decided to try my GPS "skills".  BUT, forgot to take my phone out of Airplane Mode - which was ON to save battery life.  Hence Location was screwy.  I was in a valley but couldn't tell which ridge was which, so I could not locate myself with a compass.  Not realizing I was in Airplane mode the GPS gave me bad Location info, and I had to give up on it.  Used the compass to keep a steady direction South or West.  Hit an actual road after 3 hours in the rain.  Wool is my friend.


Gonna learn this digital stuff if it kills me. 


So how do you get those darn grid lines in LTspice?

[shooter]

didn't make sense to me but maybe for you 

https://www.eevblog.com/forum/beginners/ltspice-xvii-gridlines-in-waveform-viewer/

[jjasilli]

Successfully completed sim of Real-World Capacitor: adding R & L.

@ shooter: Grid Lines -- Yes, thanks! That site describes an earlier release, so it's a little different, but enough to point me in the right direction. 


How to add Grid Lines to the Plot Plane (graph) in the newest version of LTspice XVII:  Right Click in middle of the Plot Plane.  A Dialog Box appears > Left Click View in the Dialog Box (This is a different "View" from the one on the top toolbar!!!) > Left Click Grid. Bingo!

[shooter]

Right Click

Left Click

sounds like the guy that called the square dances in Kty 

[PRR]

This thread (elsewhere) is well recommended. I have not read it.
DIYA: Installing and using LTspice IV (now including LTXVII). From beginner to advanced.
I think that is a public section. If not, it may be worth Joining just to read it.

Mooly's posts will be excellent. As all threads everywhere, some other members are just noise.

[PRR]

> digital mapping makes it possible to significantly scout an area in advance.

I scouted a couple dozen properties in Maine from New Jersey. The real estate ads say one thing, sky-birds may show something they omitted. One was "in" a nice town but really way-way out on wetish land. Another backed up to an active gravel quarry. Sometimes Street View showed a less interesting angle than what the realtor wanted to show. The place we made an offer on is long and skinny so how close are the neighbors? I found Glen's roof and neighbor Jimmy's house-- acceptable, and saw that nobody had built on the other side of this plot. (It didn't show that the front acre was wet 80% of the year, though I might have guessed by full-grown trees dead/brown on the stump.... it drained before they put the road in, then it took decades for the trees to root-drown.)

[jjasilli]

This thread (elsewhere) is well recommended. I have not read it.
DIYA: Installing and using LTspice IV (now including LTXVII). From beginner to advanced.
I think that is a public section. If not, it may be worth Joining just to read it.

Mooly's posts will be excellent. As all threads everywhere, some other members are just noise.

Thanks, PRR! That DIYA thread looks promising. I think I'll finish Kuehnel's Chapter 1.  Then start over withe DIYA thread.

[PRR]

> sounds like the guy that called the square dances in Kty

That may be the start of a good analogy. While PSpice clicking can be awkward, LTspice functions seem to have been invented by *several* dance-callers.

This is especially disturbing if you use one sim and switch to another. Things that "should be" ON the drawing turn out to be in the menus or right-click or by typing Directives onto the drawing (I'm not used to software which takes directions from text on a drawing).

But circuit invention is a very abstract concept, never going to be as natural as painting landscapes with a paintbrush.

[jjasilli]

Actually LTspice has gotten me better at using my laptop & its mouse pad. 


BTW one online reviewer of spice programs opined that they all have poor user interfaces (UI's), because the developers who can grok the inner workings of the spice programs tend to be inherently bad at UI.  Sounds good to me.  E.g., changing the font size in LTspice, which is way too large by default, is anything but straightforward.

[shooter]

never going to be as natural as painting landscapes with a paintbrush.

 
you've never watched me trying to mix the 
yellow grass to match 

[jjasilli]

Am away from home for the weekend with laptop, but no Kuehnel book.  So I went through the 1st page of the DIYA site on LTspice.  Definitely worthwhile.  Also downloaded PDF of ist Ed. of "Audio Power Amplifiers", by Bob Cordell.  Also seems promising and a wndow into SS amps.  Anyway Ch 24 also has LTspice how to's.

[jjasilli]

Got 3/4 through creating a pot symbol per Kuehnel.  If doing Spice is getting into the weeds, creating symbols is like getting tangled in them!  Discovered I could join the Yahoo LTspice Group, and download lots of pre-configured components and circuits!  Just put *.asy files in the LTspice/sym folder, and they show up in the component dialog box.  Not yet sure what to do with *.asc files. EDIT:  asc = schematic (Duh!)


Also lots of info & help in the Yahoo Group.

[PRR]

> getting into the weeds, creating symbols is like getting tangled in them!

Yes; this should be an Advanced Skill, but the lack of pot "forces" us to go into the weeds. My notes:

"--- OK. Two hours to get a pot model working. One screw-up is I typed "pop" instead of "pot", duhhh! Also got out-of-order in the lines on page 25, duh. Mildly compounded by refusing to name the pins in-out-common, trying 1-2-3, then top-wip-bot, but that was not the issue. Also ignored zig-zag artwork for a simple box with sidearm, which is fine. Parameters R and A pass-through properly. Works for .AC. Found how to list 2 (3?) parameters as list instead of line."

Does your text have "gmin" in the pot model? (It saves a math blow-up at 100% or 0%.)

[jjasilli]

Not sure how to respond.  I still haven't finished the Kuehnel pot "build".  Attached is the Yahoo Group pot I downloaded.  Not sure about the "text".

[PRR]

> Not sure about the "text".

Page 28 (in my pre-press copy).
"Convert the two resistors into a SPICE subcircuit...." ... "Save as a text file pot_V1.txt..."

Subcircuit code is:

Code: [Select]

R1 in out {(1-A)*R}
R2 out common {A*R}
Improved code:

Code: [Select]

R1 in out {((1-A)*R)+gmin}
R2 out common {(A*R)+gmin}(gmin is a very small number, default 1e-12.)

[jjasilli]

Pagination is correct.  Added gmin to p. 28 & to my text file.  Thanks!


EDIT: Kuehnel corrects p. 28 on p. 32.  Looks like he was trying to make a point.  Anyway my pot appears to work. passing the .75 & 1. Test.