Alan,
I just tried the new part in place of the old one. Originally, when I
designed the symbol for it (it's an SBL-1 mixer), I just used the
standard "wagon wheel" for the symbol for it, the TUF-1, ADE-1 and a
homebrew version of the SBL-1. Then, I realized when doing the first
board, I had no convenient way to connect the external grounds and the
two IF pins together (doh!). I was trying to force wiring on the
board view, and I didn't care for that much.
I redesigned a rectangular symbol with 4 pins on each side, and drew
the wagon wheel mixer symbol inside it at .0125" grid resolution, and
added the text to it. Then I switched back to .1" resolution to make
sure the pins would connect on the schematic. I renamed the pins fro
P$1 etc. to (in order, as the are one the actual device) RF, GND@1,
IF@1, IF@2, GND@2, GND@3, GND@4 and LO for pin #8. By the way, as
expected, the "@1" doesn't show up on the symbol. I set the pin to
display the nam on the symbol only, and it just shows RF GND IF IF
and then GND GND GND LO coming back up the other side.
I just added them to the schematic of the product detector/audio
schematic I'm working on, and it looks good on the schematic and
board. I disconnected the grounds temporarily to test that "auto net"
thing with a supply. I added a +12V supply and connected it to a
transistor, and it didn't connect any of the grounds. Then, I
arbitrarily connected the +12V to the LO pin, and again, no
auto-ground connection. Maybe it will only do that if you have a part
with a voltage supply defining one of the pins, like maybe on a 7812
regulator, or something. The regulators that are in the libraries
don't do that, however.
I'm the wrong person to ask about vias. I just made my first ones, on
a board with some MMIC amplifier devices on the top ground plane side,
along with the PA transistor at the other end of the board. I ∗think∗
I'm doing it right; it added a via pad to the board, and I'll connect
it through with a piece of wire. Click on DRC, and then read the
information regarding minimum drill for the Sizes and Restring tabs.
I don't completely understand it (it's Eagle!), but the Japanese
tutorial suggested setting Restring at 40%. I've had many situations
where I had DRC errors for drill size, but I just ignore them, since I
don't send the boards out for fabrication. I don't even print the
boards from the program, which could show the drill holes. I export
them to .bmp files and edit them in Photoshop, adding text, making
pilot holes, and use the "Threshold" control of Photoshop to ge a pure
black and white image for printing. It adds a considerable amount of
time to do it that way, but that's the way I've always done it. Until
I figured out the "polygon gnd" thing, I even added fills using
Photoshop.
As to the specs, well, I pretty much ignore those as well. After I've
finished routing, I usually go back with the "Wrench" tool and
redefine the traces to a wider trace, typically .032", as long as it
still passes DRC. I have seen specs for digital and mixed analog
layouts on some sites, along with specs for signals crossing under
other signals. Obviously, signal trace widths and layer crossings are
extremely critical at VHF and UHF, where the foil traces are inductors
and capacitors. I haven't seen any guidelines for HF, but I try to
use common sense. I tie the top ground plane to the bottom foil layer
in several places, and I'm careful not to put a large trace across a
critical section where capacitance through the 1/16" thickness of a
board would be a problem. For example, for those GHz-capable MMIC
amplifiers mounted on the top layer, I left the foil side of the board
blank underneath them and their circuitry to hopefully preclude VHF
oscillations.
When I get the other mixer device symbols corrected, I can send you a
copy of the small custom library they're in, if you want it. I also
have some toroids in there (bifilar and trifilar FT37-43, etc., and
the Mouser 42IF123 IF can transformer that is used in several QRP rig
designs. Also a board-mounted RCA jack that I found at a local
surplus house, to use for board-to-board connections with coax.
Ted
--- In Homebrew_PCBs@yahoogroups.com, Alan Marconett <KM6VV@...> wrote:
>
> Hi Ted,
>
> I saw parts with hidden supply pins get connected, but trouble is,
there
> are many ways to call pins, VDD, VCC, GND, VSS. And Eagle doesn't
seem
> to have a way to "alias" them together when they should be.
>
> Did you notice the GND@1 and GND@2 convention? you might try the @
> convention to tie your pins together.
>
> Time for my question, I just finished routing my board (by hand!),
and
> I see that I have vias that somehow have the wrong hole size? They
> show up on the design rules check. I have 12 mil signals and 24 mil
> power traces. They need changed, but what's the spec?
>
> Alan KM6VV
>
>
> kilocycles wrote:
> > I'm re-doing some components I previously created (in Eagle, but this
> > probably applies to other CAD pacakages as well). The actual
---snip---