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Subject: RE: Help with a PCB Layout

From: Ted Bruce <kilocycles@...>
Date: 2006-01-17

Bob,
I haven't seen the 16F7X7 anywhere yet; it's not in
eithe of the microchip libraries that I have, nor in
DL4YHF's yhf_spec.lbr.

I've had pretty good success in creating new symbols,
packages and devices in Eagle, after a learning curve.
I have the tutorial that is written obviously by a
native Japanese speaker, but diction and sentence
structure aside, it makes pretty good sense.

I've made the following devices so far: Minicircuits
SBL-1, TUF-1 and ADE-1 RF mixers (the ADE-1, a surface
mount device, I made to go on the bottom layer foil
side of the board, so I had some pin and pad juggling
to get that one right, as I only do single-side
boards); a Mouser 42IF123 IF transformer, and a couple
of upright T50 and T37 toroids, one a bifilar-wound
one; and Omron 6A-274 and RadioShack 275-249 relays.
The only issue that I currenly have is with drill size
assignments; Eagle DRC always tells me the bifilar
toroid drill size is too small. Doesn't matter to me,
since I fabricate my own boards.

The key to making symbols that will connect is that,
regardless of what grid resolution you create the
symbols in, switch back to a .1 inch grid before you
place the pins. Also, remember which pin assignments
you've made so that when you connect the symbol to the
package when creating the device, you know which is
which.

When I made the Omron relay, I started with a basic
DIP symbol and package and deleted the pins I didn't
need, and added the extra symbols for the coil and
contacts. Whwn I made my second relay, I just started
from scratch and found it to be easier, since I knew
how the pin and pad sequences were assigned, because I
did the assignment.

Now that I've done a few, and I don't have to read the
tutorial for every little thing, it only takes me 20
minutes or so to make a device, depending on how fancy
I need the symbol to be.

Regards,
Ted Bruce KX4OM

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