Re: gEDA-user: passing parameters to a subckt

[kai-martin knaak <kmk@xxxxxxxxxxxxxxx>]

al davis wrote:

> Ah ..  there's a good idea ..  "don't have to be exact" .. they
> never are ....   Not detailed, but just good enough for a
> beginner. ......  Now we need a volunteer to do it.
> 
> Have things like a generic parameterizable op-amp. .. with
> parameters like gain, gbp, and so on.

Parameterized models are already for the user who got beyond the 
first successful projects. For the first steps, there should be
as little room to screw up as possible.

While parametrized models are great and should be provided
in the default install, there should be a set of ready-to-use
generic models too. For the getting started stage, it is 
these ready-to-use models that matter.


> Can you make a list of the ones that should be included?

Ok, this is what I'd regard as essential to get started with 
simulation. I chose components that represent common, cheap 
components in the real world:

1) ideal passives with their nominal value as parameter:
    resistor 
    inductor
    capacitor
  IIRC, these are already readily available in a default install
  of gnucap.

2) diodes: Any generic diode would do. If in doubt, the parameters 
   of 1N4007 should do.

3) bipolar transistors: Any of the kind that is commonly referred
   to as universal silicon "TUN", or "TUP". Say, BC847 / BC857 

4) Signal FETs: Again, any of the generic silicon models would do. E.g
   BSS123 / BSS80

5) Power FET: Some common NFET that comes in TO220 package, e.g. IRF720

6) Opamps: 
     a) An ideal opamp with essentially infinite amplification, infinite  
     	slew rate, zero bias current, no input offset, etc.
     b) A more realistic model of a common opamp, with bipolar input, 
	e.g. OP07
     c) A more realistic model of a common opamp with FET input,
	e.g. TL081
     d) A more realistic model of a common fast opamp, e.g. LM833

7) Comparators. Like with the opamps, an idealized model should be 
     complemented with a common real world component. E.g. LM393 

8) Signal source with the capabilities of a simple frequency generator
     (sine, square, triangle, pulses, sweep)

This set of components would already allow for lots of non trivial 
simulation. Other integrated components like analog switches, voltage 
constants, transformers, or mixers would be nice to have. But they 
are not essential to get started.

 
> The vast majority of gnucap users are not geda users.

This might change, if geda provides a way from schematic to 
simulation that is as straight forward as the way from gschem 
to pcb.

---<)kaimartin(>---
-- 
Kai-Martin Knaak
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