[Ktechlab-devel] New guy <--

[Alan Grimes]

Glen wrote:

> Hi there all. I just discovered ktechlab yesterday as an option to
> install into a Ubuntu system.

> This looks like... it has a TON of promise. I love the real-time
> oscilloscope and the simple way of dragging a component and hooking it up.

It's more of a chart recorder than a 'scope but it is fairly useful....

> I've been reading the archives and I'm glad it's been resurrected from
> the dead. I *also* want to get vacuum tube / valve diodes, triodes, and
> pentodes implemented ;) I'm pursuing simulation of analog audio circuits

I'm working on a class AB1 2A3 push-pull design. I've selected a design
based on the voltage gain and driver stage in Morgan Jones' Crystal
Palace amp.

Open problems in the design is the input stage... I want to support both
balanced and single ended input and there's also the problem of feedback
because I'll be pushing the output stage into AB1, I need to use
feedback to moderate the distortion...



>The rest of the EDA stuff on GNU/Linux systems, like gEDA, are a nasty pain
> to use.

;)

> I've got some C++ background mostly in QT3, a bit of OGL, and I'm a
> professional tech doc writer for a living who is very impatient with
> software so I tend to simplify the interfaces I write to the bare
> minimum while remaining complete. I'd love to contribute; this is a
> sweet-looking project.

Welcome aboard.

> So the question is, what should I do and where should I start?

here's the biggest bug I'm seeing on my machine...

I have this simulation of my father's Harman Kardon 430 (from 1974)...
The amp works (even though it doesn't seem to for the first few
minutes... the real amp takes about 30 seconds for the input
differential amp to un-clamp... =\

the problem is when I go to save it and load it, the entire circuit is
messed up. 2/3rds of the connectors are gone, there are a lot of
dangling junctions.... Undo/redo creates a similar effect. The problem
must be in the document heirarchy, It's all based on QT's DOM/XML engine.

On the simulation engine, an important issue is that temperature is
currently a constant. Temperature is an important variable in solid
state circuitry, my harman kardon sim, for example, can't simulate the
thermal diodes that are used to throttle the power stage. My idea was to
implement heatsink domains so that all components in that domain are
simulated at a temperature based on the total power dissipation in that
domain scaled by the heatsink coeficient...

In classic electronics, the issue is how emissive the cathode is... This
is an issue as the device warms up...

> Incidentally, would there be any plans to implement free-rotation, so
> that the diodes in my bridge rectifier can actually be placed in the way
> they are normally drawn on a schem? gschem doesn't do it and I think
> qucs doesn't either.

The most important issue right now is to implement multiple winding
inductors, IE transformers... That's a serious deficiency at present...

[later]

> Is there any direction / ideas for what direction the simulator should
> go?

I've made some proclamations, but those are only directed at people who
don't have their own ideas. ;)

> I have my own ideas, especially now since I've probed the code a
> little bit, but what's really better for the project?

Lay them on us!

What's best for the project is that you get hooked on tweaking stuff....


> What would people like to see it do beyond what it does now?

me need triode. ;)

Seriously, we need to implement a components database. The worst will be
configurable devices that might have variable numbers of grids (with
variable densities), and inductors with variable numbers of coils with
variable numbers of turns...


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