I considered for a while if my contribution to this topic would be
meaningfull.
It is indeed true that most projects are not too difficult on the electronic
part, but the mechanical part is where many projects fail.
As a HAM radio amateur I have seen this often. I learned to think out the
whole
mechanical construction before I even start picking up tools. In my mind I
had
built the pdp8/e console several times in several variations of
construction.
The result is something that I can make (the parts) and can build (putting
it
all together), all by myself. But I must admit that the tools I use (and
some
help) are outstanding: the prototype building labs of Oc? R&D. They even
have
a laser cutting machine that cuts any shape out of 10 mm thick steel!
Regarding FrontpanelExpress, I looked at it (they also have a shop in
Germany,
so that is good for us Europe-based people). I had many questions, like can
they deliver the frontpanel with the correct colors and artwork (lettering)?
And then: you have a nicely cut (no doubt about that) frontpanel, but would
you like the lamps or LEDs to be visible through *holes* ?
I wanted the result to measure up to the original: a high standard because
the D|I|G|I|T|A|L frontpanels are a work of art (as most classic computer
frontpanels are).
I did not want to have holes in the front for the lamps, so I would still
need
1 mm thick plexiglass or lexan ... and that must also have the openings for
the
switches (not for the lamps of course).
That is why my solution is *two* pieces of 1 mm thick plexiglass. The
openings
for the switches are cut in the two pieces in one go, so they line up
perfectly.
I used CorelDraw to draw a copy of the frontpanel - pictures from several
web
sites was all I had. After all was drawn, I turned off "snap on grid" and at
400% view I moved some lettering to get it better centered.
An other difficult part are indeed the switches.
First, I must say that I *never* had the intention to make a 1:1 replica of
the
frontpanel. My museum is already quite full as it is (with even more to
come)!
I searched for paddle type switches, normal and spring-loaded. Not easy, but
the ones I found can still be ordered, but they are indeed rather small: the
lebgth of the paddle is approx 12-15 mm (IIRC) and the width is 10 mm. If
you
have thick fingers the size is really small.
The size of the switches determined the total length of the frontpanel which
is still 36 cm. The height is then set by proportion compared to the real
frontpanel.
As Ethan said it: you must make the size of the switches and the frontpanel
proprotional to eachother. If you want the frontpanel to be as close to the
original as possible it must be 19" wide. Small switches is definitely not
what you want in that case!
The ones used on the FP6120 look bigger than the C&K ones that I used, but
the finishing touch is of course to get them in the correct color.
More work, but I said it on my website: the end result is very depending on
the effort and time you spend on the frontpanel.
Rich mentioned the price tag. He is correct that you must do the math.
The switches are easily costing $4 a piece, and for a PDP-11 or -8
frontpanel
just the switches will set you back some $80 to $100.
The whole project costs all-in-all $250-$350, when you can do most of the
work yourself.
Rich also mentioned Future-Active Electronics. I assume this is their site:
http://www.future-active.com/ Can you give a partnumber Rich?
The problem with designing a PCB for the LED's and switches is not the
electronic part, as said in the beginning of this e-mail :~) The design is
simple and straight-forward *if* you have the dimensions of the switches
that
are going to be used. Making a frontpanel PCB is only useful if you know
before how many are going to be wanted (and bought!) *and* you know for sure
that the required amount and type of switches is available.
Note that you *still* need (metal) work before you start soldering the
switches
to make sure that they line up perfectly. If you just solder the switches in
the PCB you will see that you could get them lined up better. I guess that
you get solve that by soldering only *one* pin of all the switches, and then
line them up using the soldering iron and three hands :~)
Same story goes for the LEDs, but depending their visibility (when they are
off)
you get get away with a less than perfect alignment ...
One thing you must consider -- and I forgot that in my construction!!
The frontpanel plate will have some distance to the plate where the switches
are
mounted on - or if you like: the PCB where they are soldered on.
Keep that distance in mind when you solder the LEDs (or lamps). Try to get
the
LEDs as close to the frontpanel as possible. The LEDs will most certainly be
approx 10 - 15 mm from the PCB. In my construction, that was not possible.
I am thinking of dismatling the panel and cut the strip with the LEDs out of
the backplate. Then mount that strip with stand-offs back on the backplate.
The big thing that is withholding me is that I must desolder all wiring ...
count the parts and the needed wires to the frontpanel: a lot!
thanks for the nice feedback on my project,
- Henk, PA8PDP.
Received on Wed Feb 02 2005 - 01:41:39 GMT