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[R.Lewis]

"Peter Bennett" <peterbb@nowhere.invalid> wrote in message
news:btkuk05ogfi73ob1ctgb24vk9fj38u8et6@4ax.com...

On 20 Sep 2004 10:46:11 -0700, support@pcb123.com (MrWizard) wrote:

Hello everyone,

As a designer of a PCB / Schematic Design tool I am continually asked
for more libraries. However, except for a few exceptions I am finding
it exceedingly difficult for anyone to give me up there "list" of most
common or useful components.

We (PCB123) are getting ready to create thousands of new schematic
symbols and PCB footprints (land patterns) but we would greatly
appreciate the communities input to help us put this list together.
PCB123 is used by all technology / experience levels from Tube amps to
High Speed RF Designs.

I use Protel for schematic and PCB design. Based on my experience, I
suggest that your programs should have easy-to-use library editors, so
that the user can make his own parts.

Alhtough I have been using Protel for many years, I find I usually
have to make new schematic parts and PCB footprints for almost every
job I do. (I do work on a wide variety of projects - I expect many
people will use a smaller variety of parts, and will soon get
everything they need built.)

There are so many different parts currently available, and more
introduced every day, that we can't (or shouldn't) expect any CAD
vendor to have everything in the standard libraries, as long as the
package comes with a reasonable selection of common parts - resistors,
capacitors, transistors, 74xx TTL logic, 78xx voltage regs, etc...

Protel does come with a large library, but I often find it quicker to
make a part myself, rather than seach through all the libraries to see
if it already exists.

I can re-iterate that.
Not everyone is continually laying out PC style motherboards, memory planes
and the like.
For many products the ability to produce a custom part is almost
imperative - a quick look has shown that I have (admittedly gained over a
goodly number of years) 16 versions of the bog standard LM317T .
Twelve have been product-specific forms used in volume consumer products the
other four have been extensively used in all sorts.

 

[Boris Mohar]

On 20 Sep 2004 10:46:11 -0700, support@pcb123.com (MrWizard) wrote:

Hello everyone,

As a designer of a PCB / Schematic Design tool I am continually asked
for more libraries. However, except for a few exceptions I am finding
it exceedingly difficult for anyone to give me up there "list" of most
common or useful components.

We (PCB123) are getting ready to create thousands of new schematic
symbols and PCB footprints (land patterns) but we would greatly
appreciate the communities input to help us put this list together.
PCB123 is used by all technology / experience levels from Tube amps to
High Speed RF Designs.

I will be continually monitoring this group as well as a forum I have
created specifically for this process:
http://www.pcb123.com/community/content/modules.php?name=Forums

We will be releasing a whitepaper that opens up our library format to
third-party developers that will make it easy create new symbols and
footprints. We are also open to partnering with other developers such
as http://tinycad.sourceforge.net/ to integrate with PCB123.

Any and all feedback will be appreciated.

Thank you,

Todd Clifton,
PCB123 Product manager
www.pcb123.com

Instead of creating thousands of symbols, create a powerful and easy to
library editor. Make it possible to edit the part directly in the schematic
or at least shuffle the pins around. Have a look how Orcad has done it and
don't do it that way. It is a peace of crap. I should know, I use it.
( the devil you know etc..)

Ditto for footprints. Make sure that the pad array generator is full
alphanumeric and works in imperial and metric.






Regards,

Boris Mohar

Got Knock? - see:
Viatrack Printed Circuit Designs http://www3.sympatico.ca/borism/

 

[Paul Burke]

R.Lewis wrote:

For many products the ability to produce a custom part is almost
imperative - a quick look has shown that I have (admittedly gained over a
goodly number of years) 16 versions of the bog standard LM317T .

One of EasyPC's good points is the ease of creating components- it
positively encourages the creation of a whole sequence (e.g. it's easy
to produce the whole series 2-4-6-8-10 etc in a family of connectors).
It has its faults- like the padout must have at least as many pads as
the schematic symbol, and you can't assign one schematic pin to multiple
pads- but I've never felt the need to go hunting for components.

Paul Burke

 

[Charles DH Williams]

In article <22a89a25.0409230804.675e11a0@posting.google.com>,
wangllu@yahoo.com (cici) wrote:

I am doing some simulation of VCO (4 stage differential) in spice3.
When I do the .tran analysis, the time interval of the output is not
uniformly distributed. It is not the time step I gave in the command:

.tran Tstep Tstop.

In my work, I need the timestep to be uniformly distributed. How can I
control it?

use the 'linearize' command:

http://newton.ex.ac.uk/teaching/CDHW/Electronics2/userguide/sec5.html#5.3.23

Also, note the comments about not setting Tmax in

http://newton.ex.ac.uk/teaching/CDHW/Electronics2/userguide/sec4.html#4.3.9


Charles.

 

[Steve]

On Thu, 23 Sep 2004 17:36:48 +0100, Charles DH Williams
<C.D.H.Williams@exeter.ac.uk> wrote:

In article <22a89a25.0409230804.675e11a0@posting.google.com>,
wangllu@yahoo.com (cici) wrote:
I am doing some simulation of VCO (4 stage differential) in spice3.
When I do the .tran analysis, the time interval of the output is not
uniformly distributed. It is not the time step I gave in the command:

.tran Tstep Tstop.

In my work, I need the timestep to be uniformly distributed. How can I
control it?

use the 'linearize' command:

That will certainly work, although if the samples are intended for use
with an FFT, the linear interpolation will introduce enough error that
the noise floor will be rather high -- like -90db from the signal, at
best...

--Steve

 

[Chaos Master]

Boris Mohar says:

Instead of creating thousands of symbols, create a powerful and easy to
library editor. Make it possible to edit the part directly in the schematic
or at least shuffle the pins around. Have a look how Orcad has done it and
don't do it that way. It is a peace of crap. I should know, I use it.
( the devil you know etc..)

Ditto for footprints. Make sure that the pad array generator is full
alphanumeric and works in imperial and metric.

Something I would like would be a 'library sharing' web page.
Someone creates a symbol. The symbol looks good? Share it.

I once tried to do this with SPICE models, creating a big "database" to be put
online but I couldn't go on, because of lack of time.

The problem would be the various software packages...
(SPICE models are universal)

[]s
--
Chaos MasterŽ, posting from Brazil.
"Two of the most famous products of Berkeley are LSD and Unix. I don't think
that this is a coincidence."
-- Anonymous

"I'd rather be hated for who I am, than loved for who I am not" - Kurt Cobain

The Evanescen(t/ce) HP: http://marreka.no-ip.com

 

[Charles Schuler]

"meg" <mbkhad@yahoo.com> wrote in message
news:95d8e5a8.0409281430.46dcb192@posting.google.com...

Hi there,
I want to design an amplifier with voltage gain 0.5, which can be
used in a pipelined digital to analog converter..
I can do an inverting amplifer.. common drain type mos amplifier..(am
i on the right path?)
Can use some help on the same..

A voltage divider will give you a gain of 0.5. However, if you also need
current gain or an impedance transformation, then an amplifier might be
required.