Re: gEDA-user: OFF: capacitors for RF power amplifier
> I'm currently designing a power amplifier for the HF (3-30MHz) radio > band. > > I am selecting capacitors for the low pass harmonic filter bank at the output. > My question is what kind of capacitors should I use? I apply not more then > 100V of say 30MHz maximum. > > My best bet is to use X7R capacitors with as much DC voltage rating as I can > get. I don't know if there's any connection between the DC and AC losses. > > > Thanks, > Levente > The biggest problem can be the current handling capacity. Very few capacitor makers specify this. Usually if a capacitor is rated for 100V this means 100V DC wthout any current. Only special purpose capacitors for RF power applications have HF current ratings, see Anerican Technical Ceramics for example: http://www.atceramics.com For RF do not use X5R/X7R (good only for supply bypassing), use NP0/C0G or similar low loss ones. Their maximum capacitance is limited to few nanofarads in 1210 case, so it may be necessary to connect few in parallel to get desired value. Also if you do not have capacitors with high current ratings, connect several smaller ones in parallell instead of one big. Foil type capacitors are suitable for lowest frequencies (LW/MW) and have to be low loss. Polipropylene or teflon ones are low loss and usable, while poliester ones are too lossy. Parasitic inductance can also be a problem. Check your PA circuits with circuit simulator for resonance effects. In this case currents and voltages can be much higher. Wojciech Kazubski ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: Attribute Net (without pin assignment) - for Powerand Port Symbols
On Tue, 2011-04-12 at 23:46 +0200, Wojciech Kazubski wrote: > First, allow symbols to contain net segments, now this is forbidden in symbol > creation guide. > Replace pins in power/gnd symbols with net segments, this segment can have > label (and should have to be usefull). > If circuit parser encounters net segment inside symbol, it adds it to the net > as any other net segment and sets a net name. > Any nets having the same name are assumed connected together (as is now). > This idea should work also for subcircuit ports and inter-scheet connections. The idea is sound, but the problem is that the user cannot currently override such attributes from the schematic. The case we're mostly talking about here is the generic power symbols which the user modifies a net=???:1 attribute to assign a name. Just to touch a personal note with those asking for removal of the :1 suffix on the net=... attributes. I usually make a separate visible label attribute and hide the net= attribute. This seemed like a nice idea.. until the day I ended up with a bunch of boards to rework due to having edited the visible label= and not the net= attribute! So yes.. I can see a need for the feature ;) -- Peter Clifton Electrical Engineering Division, Engineering Department, University of Cambridge, 9, JJ Thomson Avenue, Cambridge CB3 0FA Tel: +44 (0)7729 980173 - (No signal in the lab!) Tel: +44 (0)1223 748328 - (Shared lab phone, ask for me) signature.asc Description: This is a digitally signed message part ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: Attribute Net (without pin assignment) - for Power and Port Symbols
On Tue, 2011-04-12 at 16:51 -0400, DJ Delorie wrote: > > How about component-level attributes like pin.5=vdd, pin.1=gnd ? > > Bonus if you make "pin.foo=" for for a pin with pinlabel "foo" :-) We can't differentiate like that, since "pinnumber" can be a text string as well. "pinnumber" is what gnetlist cares about really. -- Peter Clifton Electrical Engineering Division, Engineering Department, University of Cambridge, 9, JJ Thomson Avenue, Cambridge CB3 0FA Tel: +44 (0)7729 980173 - (No signal in the lab!) Tel: +44 (0)1223 748328 - (Shared lab phone, ask for me) signature.asc Description: This is a digitally signed message part ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: Attribute Net (without pin assignment) - for Power and Port Symbols
On Apr 12, 2011, at 2:56 PM, Stephan Boettcher wrote: > A non-graphical netlist format could be a gschem schematic file with a > generic symbol without any pins, with just a list of attributes. You mean like the files produced by pins2gsch? http://www.gedasymbols.org/user/john_doty/tools/pins2gsch.html John Doty Noqsi Aerospace, Ltd. http://www.noqsi.com/ j...@noqsi.com ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: Attribute Net (without pin assignment) - for Powerand Port Symbols
> > > > > > > I would advise a note of caution. > > > > What some people do not like is the visible :1 in schematics -- can we > > simple suppress that output for symbols with only one pin and digit 1 > > after the : > > That would be a not too dangerous patch, because it concerns only > > graphical output. > > > > > +1 > Special case seems wrong. This would be a much nicer alternative. Consider this one: First, allow symbols to contain net segments, now this is forbidden in symbol creation guide. Replace pins in power/gnd symbols with net segments, this segment can have label (and should have to be usefull). If circuit parser encounters net segment inside symbol, it adds it to the net as any other net segment and sets a net name. Any nets having the same name are assumed connected together (as is now). This idea should work also for subcircuit ports and inter-scheet connections. There is no need for special virtual components that do not have footprints. The main problem may be the compatibility with current system. Wojciech Kazubski ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: Attribute Net (without pin assignment) - for Power and Port Symbols
Peter Clifton writes: > On Tue, 2011-04-12 at 22:35 +0200, Krzysztof Kościuszkiewicz wrote: >> On Mon, Apr 11, 2011 at 11:25:19PM +0100, Peter Clifton wrote: >> >> > What about the cases where this is a mistake? The net= attribute was >> > supposed to refer to some implicit power pin - not the device's one >> > symbolic pin, but the user forgot the suffix. >> >> The special case applies only to symbols with a single pin, so no such >> error is possible here. > > What about symbols with one pin, and multiple net= attributes providing > hidden "pins". A non-graphical netlist format could be a gschem schematic file with a generic symbol without any pins, with just a list of attributes. Instead of special case, we could call it a default. If a net= attribute does not provide a pinnumber, it defaults to 1. Doesn't make is any better, but maybe feel better :-) This default is actually a natural and useful default. I'd welcome it. Whenever I forgot to put a pinnumber on a net= attribute, this default would have fixed the schematic, not hide an error. -- Stephan ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: Attribute Net (without pin assignment) - for Power and Port Symbols
> How about component-level attributes like pin.5=vdd, pin.1=gnd ? Bonus if you make "pin.foo=" for for a pin with pinlabel "foo" :-) ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: Attribute Net (without pin assignment) - for Power and Port Symbols
How about component-level attributes like pin.5=vdd, pin.1=gnd ? You could make a blank rectangle symbol with a refdes and a list of a few of those pin.N= visible, let the user edit them... gnetlist would have to look for all pin.N attributes, and connect that pin N to the given net. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: Attribute Net (without pin assignment) - for Power and Port Symbols
On Tue, 2011-04-12 at 22:35 +0200, Krzysztof Kościuszkiewicz wrote: > On Mon, Apr 11, 2011 at 11:25:19PM +0100, Peter Clifton wrote: > > > What about the cases where this is a mistake? The net= attribute was > > supposed to refer to some implicit power pin - not the device's one > > symbolic pin, but the user forgot the suffix. > > The special case applies only to symbols with a single pin, so no such > error is possible here. What about symbols with one pin, and multiple net= attributes providing hidden "pins". -- Peter Clifton Electrical Engineering Division, Engineering Department, University of Cambridge, 9, JJ Thomson Avenue, Cambridge CB3 0FA Tel: +44 (0)7729 980173 - (No signal in the lab!) Tel: +44 (0)1223 748328 - (Shared lab phone, ask for me) signature.asc Description: This is a digitally signed message part ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: Attribute Net (without pin assignment) - for Power and Port Symbols
On Mon, Apr 11, 2011 at 11:25:19PM +0100, Peter Clifton wrote:
> What about the cases where this is a mistake? The net= attribute was
> supposed to refer to some implicit power pin - not the device's one
> symbolic pin, but the user forgot the suffix.
The special case applies only to symbols with a single pin, so no such
error is possible here.
> Our power symbols already fell like a bit of a kludge as there is no
> physical pin or component which ends up in the netlist file.
>
> (Why should we have to give that power symbol's pin ANY pinnumber
> attribute? Why is pin 1 special?)
That's right - if a symbol has only one pin, then if it is :1 or :999
it does not matter. I added this restriction only because default power
symbols use :1, but that can be dropped.
> _I_ think it adds to the confusion - as it would mean there are two
> completely different syntax for the same attribute to be used in
> different situations.
>
> I don't want to see that special case code proliferate in gEDA. We have
> enough already!
That is the main case against this change - one that changes from an
"improvement" to a "kludge" :)
> A far more satisfying solution in the long run would be to make the
> symbols which annotate net naming (like the power and ground symbols,
> off-page labels etc..) have an editable attribute associated with the
> PIN which gets hooked up to the net which becomes named (or renamed).
> (netname=) as if it were on the net its-self.
That would be the best idea, of course. The power symbol with a
net=NETNAME{:PINNUMBER} actually acts same way (probably modulo gnetlist
config options) as netname=NETNAME attached to the same net.
Any idea how to make such "annotation" symbols work? Another variation
along the lines of "graphical=1"? Attributes (inherited or explicit) of
such symbol could be applied directly to the connected net/bus.
--
Krzysztof Kościuszkiewicz
"Simplicity is the ultimate sophistication" -- Leonardo da Vinci
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Re: gEDA-user: Attribute Net (without pin assignment) - for Power and Port Symbols
On Mon, Apr 11, 2011 at 8:45 PM, John Doty wrote: > > On Apr 11, 2011, at 4:25 PM, Peter Clifton wrote: > >> I would advise a note of caution. In general, I don't like it when tools >> start special casing things like this.. it just feels wrong. > > I've long thought it a minor design flaw that indexed attributes attach the > index to the value rather than the name. So, I would prefer net:1=Vcc, while > preserving backward compatibility, of course. Yes, this makes sense. Regards, Mark markrages@gmail -- Mark Rages, Engineer Midwest Telecine LLC markra...@midwesttelecine.com ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: Attribute Net (without pin assignment) - for Power and Port Symbols
On Mon, 2011-04-11 at 23:54 -0700, Russell Dill wrote: > On Mon, Apr 11, 2011 at 6:45 PM, John Doty wrote: > > > > On Apr 11, 2011, at 4:25 PM, Peter Clifton wrote: > > > >> I would advise a note of caution. In general, I don't like it when tools > >> start special casing things like this.. it just feels wrong. > > > > I've long thought it a minor design flaw that indexed attributes > attach the index to the value rather than the name. So, I would prefer > net:1=Vcc, while preserving backward compatibility, of course. > > > > You totally win! This is a really neat idea.. P pin number ":1" doesn't really matter, it is just a way of referring to a particular pin. If we could reference by other means, that would also be cool. I'm thinking of some kind of "id=..." attribute like CSS / HTML / SVG would use to refer to other elements. As someone who's just ranted against lots of magic special cases.. how would people feel to a primitive "id=..." attribute which is handled by API to look up and element's ID. We could make the code DEFAULT to looking up pinnumber= or pinseq= for pins (if an id=... doesn't exist), so the new syntax could key off id=, not pinnumber= or Basically, I want to see an unique name= or id= attribute which could be applied to any object, and is not net specific. Also - just a reminder.. All this special syntax with ":" in them, probably means there will naturally be restrictions on the presence of ":" in netnames and various ids. Is that a reasonable restriction, or should we avoid in-band data like this? We should really define what constitutes a legal character set for certain types of attribute / name, and if necessary - any escaping to be used with other characters. -- Peter Clifton Electrical Engineering Division, Engineering Department, University of Cambridge, 9, JJ Thomson Avenue, Cambridge CB3 0FA Tel: +44 (0)7729 980173 - (No signal in the lab!) Tel: +44 (0)1223 748328 - (Shared lab phone, ask for me) signature.asc Description: This is a digitally signed message part ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: RFC using SVG with semantic markup as an EDA format
On Tue, 2011-04-12 at 03:52 +0200, Kai-Martin Knaak wrote: > Steven Michalske wrote: > > >> Microsoft and Apple do not like > >> > >> > > Safari has supported SVG for a while now? Why doesn't apple like SVG? > > Sorry, I got confused by Apples dislike of flash. OT: Now there is a POV I can get behind ;) Flash makes my life a little less awesome every time it sucks the life out of one of my CPU cores, or crashes my web browser. In a vague effort to get this back on topic.. If you are every profiling gEDA or PCB for me, please ensure flash is not running (no background CPU sucking processes) before reporting results ;) I'm not sure how I like Apple's action on the issue. I doubt it was made for totally A-political reasons, and it sucks in terms of user freedom to choose what bloat-ware they wish to install. Still - I think in a way they will have given HTML5 a big boost by their actions. -- Peter Clifton Electrical Engineering Division, Engineering Department, University of Cambridge, 9, JJ Thomson Avenue, Cambridge CB3 0FA Tel: +44 (0)7729 980173 - (No signal in the lab!) Tel: +44 (0)1223 748328 - (Shared lab phone, ask for me) signature.asc Description: This is a digitally signed message part ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
