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Reply-To: "Kevin Aylward"
From: "Kevin Aylward"
References: <firstname.lastname@example.org> <email@example.com> <firstname.lastname@example.org> <email@example.com> <12j4LzC+fEp9EwgG@jmwa.demon.co.uk> <firstname.lastname@example.org> <email@example.com> <1Mup9.firstname.lastname@example.org> <email@example.com>
Subject: Re: Problems with Electronics Workbench - timestep errors
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X-Inktomi-Trace: public1-pete2-5-cust19.pete.broadband.ntl.com 1034353302 2396 220.127.116.11 (11 Oct 2002 16:21:42 GMT)
Date: Fri, 11 Oct 2002 17:21:42 +0100
NNTP-Posting-Date: Fri, 11 Oct 2002 17:21:42 BST
"The little lost angel" wrote in
> On Fri, 11 Oct 2002 08:06:36 +0100, "Kevin Aylward"
> >scale and show all signal identified on the schematic with test
> How do I tell the graphs where I want to see the signal?
Usually all you do is place the pin of a tst point on it, or alt-click
on the wire or pin...
> Say for the basic diode rectifier with resistor. How do I tell it to
> show the voltage over Diode 1 or Diode 4 or Resistor 1?
You really need to learn what proper electronics term are.
If you want to look *across* a component, which is what I believe you
mean by "over", its a little more involved then just dragging test
points, so,I do admit that, at the moment, differential probing is a bit
The are a few of ways to do this. The simplest method is if the componet
is a normal spice device such as a diode, transister etc.
Enable the DC operating points, which is the blue "OP" button.
After the run double-click on the graph and go to the Signals tab.
Say its the voltage accross diode D2.
In the signals list thery will be an entry
Check the "display" "magnitude\real" onthis entry at it will display the
the voltage (vd) accross d2
Or for, example q5[vbc] would be the voltage accros the base collector
You can also place a voltage controlled voltage source (VCVS) with a
gain of 1 on the schematic, with a resistor across its output. Put its
input across the component to be measured, and one of its outputs to
ground. Probing the other VCVS output wire will be the required signal.
You can also use the calculator. e.g.
Move the mouse over the two wires you want to probe. Make a mental note
of their names.
Double-click on the graph and switch to the Calculator tab. Select the
button that says use the calculator page set-up (instead of the current
Select one of the signal names in the Signal A list and the other in
Signal List B. Set the operator, from the list, to "-". Then ok the
> I tried alt-click on the resistor, no differences.
> The graphs only tell me some cryptic v[i] thingy
Ahmmm...v1[i], how about the current in v1?
r2[i] = current in R2....
r2[p] = power in R2
Wire voltages don't have any .
Ok, you might think this is cryptic, but seriously, what else could it
> I get three lines on the graphs despite having only one test point
> right smack over the resistor.
> And there's the perpetual warning about having no ground. The AC Sine
> wave generator doesn't have three prongs like my plugs at home does.
You *must* have a ground connected in *any* and *all* spice simulators.
All voltages are with respect to ground.
> Adding a ground anyway doesn't seem to change a thing.
Without a ground circuits usually wont simulate at all.
> >When you say AC voltage over a resistor, I believe what you *really*
> >mean is a plot of the waveform in time. i.e. a voltage against time
> >graph. In spice this is achieved by a *Transient* run. In this run
> >you set the specific frequency and amplitude of a time domain
> >generator/source, e.g. of a Sine wave, Pulse wave etc.
> Yup, I switched to TR instead of AC, and I finally got
> something on the AC graph, something that starts from negative then
> dips then become a hmm.. I dunno inverse? negative? exponential? log?
> curve never quite reaching the y-axis.
> The DC remains forever a straight sloping line. Though
> removing the resistor gives me three lines instead.. ???
I don't really know what you mean, I would have to see your actual
> Could you possibly include a simple AC/DC circuit in your next
> update and maybe I could figure out how this whole spicy thing works
There are loads of examples, have you really tried running them? Do you
mean you would like an actual AC to DC power supply example? if so email
me your email address and I will send you one.
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.
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