Re: gEDA-user: How to?

["Harold D. Skank" <skank54@xxxxxxxxx>]

Harry,

Thanks for your suggestion.  In fact, what I finally used was two
opposing sine wave sources with the delay factor for the second set for
5 cycles.  Worked like a charm.

A side issue involved the problem I ran into about the filter
calculations aborting after about a quarter of a cycle (and some 20
minutes of computation time).  I finally realized that the real problem
was that my circuit was using 12 operational amplifiers of what, 40 or
so nodes each, something around 400 total nodes in the circuit.  The
calculation was aborting when the output began to respond so that the
step size had to reduce to keep the calculations accurate.  Since I was
interested in the circuit response, rather than testing the 12 op amps,
I replaced them with voltage controlled voltage sources.  The whole
calculation ran in about 200 mS.

	Harold Skank

On Sun, 2005-07-31 at 17:17 -0400, harry eaton wrote:
> The easiest thing to so for a 5 cycle sinewave
> in SPICE transient analysis is to have a SIN
> transient source and a PWL gate to it. Use a
> poly controlled source to take the product of
> the two. Set the PWL source to zero when you
> want the sinewave gone and 1 when it is active.
> 
> vs 1 0 0 sin(0,1,1e6)
> vp 2 0 0 pwl(0 0 5u 0 5.001u 1 10u 1 10.001u 0)
> e1 3 4 poly(2) 1 0 2 0 0 0 0 0 1
> 
> makes the signal you want between nodes 3 and 4.
> 
> h.
> 
>