Electrically conductive ink

[Peter de Vroomen]

Hi,

I am looking for plotter pens (HP7475 compatible) or inkjet cartridges that
can paint electrically conductive lines on transparent plastic sheets. I
need this to repair the keyboard membrane of my old ZX81 computer .

Has anyone ever encountered something like this?

PeterV

 

[Laurence Taylor]

Hi,

I am looking for plotter pens (HP7475 compatible) or inkjet cartridges that
can paint electrically conductive lines on transparent plastic sheets. I
need this to repair the keyboard membrane of my old ZX81 computer .

Has anyone ever encountered something like this?

PeterV

Not for printers; you can get it in bottles that you paint on to the
membrane.

Or you couild try the gold or silver pens from artists shops.

--

rgds
LAurence

.... Minds are like parachutes, they work only when open.
begin Idiot driver of the week: GU52 AOH

 

[Richard Crowley]

Not for printers; you can get it in bottles that you
paint on to the membrane.

There were pens available for the HP plotters that one
could fill with whatever ink/paint. They were just like
the old drafting pens that had a small wire through the
"nib" that opened the "valve" to allow ink to flow when
touched to the paper.

Or you couild try the gold or silver pens from artists shops.

They may only LOOK metalic. May not actually be conductive.

OTOH, real, conductive silver paint is sold by better
electronic supplies vendors for PC board repair, etc.

 

[Peter de Vroomen]

Hi,

There were pens available for the HP plotters that one
could fill with whatever ink/paint. They were just like
the old drafting pens that had a small wire through the
"nib" that opened the "valve" to allow ink to flow when
touched to the paper.

Yes, and it so happens that I have a few of these. But they are pretty darn
expensive . I don't think the conductive paint will be soluble in water,
so I am putting those pens to risk. Also, the conductive paint would have to
be rather thin, and would probably run all over the plastic sheet .

Anyway, it *is* an option, but if there were ready-made plotter pens out
there, I'd rather try those first. Too thin ink is generally solved by
turning it into a gel and using it in a ballpoint configuration, so I would
expect a pen like this to be of the ballpoint-type.

OTOH, real, conductive silver paint is sold by better
electronic supplies vendors for PC board repair, etc.

One more thing that's holding me back is that that kind of silver-paint is
used by streetkids in i.e. Brazil to get high on. Not very nice stuff to
mess around with .

All in all, I'd rather use a ready-made pen .

Thanks for the replies, I'm still open for other suggestions!

PeterV

 

[Geoffrey S. Mendelson]

All in all, I'd rather use a ready-made pen .

I recently aquired a smiliar plotter and it took me over a month to find
any pens at all (I'm in Israel). During that time I experimented with
modifying various pens and pencils to work in the plotter.

If you fool around enough, it can be done. The important point is that
round ridge around the middle of the pen is needed. It keeps the pens
from sliding up and not working at all.

The other problem I had was since the pens on my plotter have to be short,
I kept getting ink on my hands, when I cut the pen down. :-(

Geoff.

 

[petrus bitbyter]

Hi,

I am looking for plotter pens (HP7475 compatible) or inkjet cartridges that
can paint electrically conductive lines on transparent plastic sheets. I
need this to repair the keyboard membrane of my old ZX81 computer .

Has anyone ever encountered something like this?

PeterV

I never saw this type of ink in plotterpens or cartridges. DIL ever sold
felt-tip like pens that contained silver-ink. They also has a
silver-containing glue. The latter is also sold by Conrad and they pretend
to have the special thinner for it as well. Bison also sells a special
conducting ink/paint/glue meant to repair window heaters. (Cars windows, not
the ones from old uncle Billy.) The foils of the type you try to repair (or
remake) are normally made by screen print (zeefdruk). It will not by an easy
job. Do you really need to repair it that way? I ever bought an old
keyboard, a type that stil had real switches and laid out the matrix with
thin wires on them. I had a lot of spare switches but I never needed them.
It worked like a charm. Guess you have the schematic of the ZX81 already.
Otherwise I can look in my old piles. Should be there (somewhere).

petrus

 

[Peter de Vroomen]

I recently aquired a smiliar plotter and it took me over a month to find

any pens at all (I'm in Israel). During that time I experimented with
modifying various pens and pencils to work in the plotter.

I had actually been thinking about this too . It's probably worth a try,
I'll give a report when I tried!

PeterV

 

[Peter de Vroomen]

I never saw this type of ink in plotterpens or cartridges. DIL ever sold

felt-tip like pens that contained silver-ink.

I have been thinking of buying one of these, shortening it, and see if I can
get it to fit the plotter .

The foils of the type you try to repair (or remake) are normally made
by screen print (zeefdruk). It will not by an easy job.

I know. For screen printing I would have to get the whole setup first
(darkroom, fotographic transfer stuff, chemicals, whatever else is needed).
It is an option, but using a plotter, I could let the plotter draw the
design. It is as reproductible (is this a good English word?) as
screen-printing, but easier to set up. And the fumes from the silver paint
won't get to too high levels .

Do you really need to repair it that way?

Well, I'd *like* to. One of the connection tabs on the keyboard is ripped,
so I have to either make up a new tab or replace the whole layer. I'd rather
replace the complete layer if it is feasible.

Guess you have the schematic of the ZX81 already.

Yep, it can be found on the internet easily. I want to try to restore the
ZX81 to it's original state. The looks of the ZX81 are very good, the
keyboard is undamaged, except some stupid fool ripped (no seriously, it
wasn't me ) a complete tab off the keyboard.

PeterV

 

[Dr. A.T. Squeegee]

Hi,

I am looking for plotter pens (HP7475 compatible) or inkjet cartridges that
can paint electrically conductive lines on transparent plastic sheets. I
need this to repair the keyboard membrane of my old ZX81 computer .

Using a plotter seems like gross overkill for something like this,
and I've never seen plotter pens with conductive ink.

Would it not be easier to do this by hand? Or perhaps ask the gang
on the Classic Computers mailing list (classiccomp.org) if anyone has a
ZX81 keyboard (or entire system) they can sell you?


--
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(Known to some as Bruce Lane, KC7GR)
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Motorola Radio Programming & Service Available -
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[Richard Crowley]

Using a plotter seems like gross overkill for something like
this, and I've never seen plotter pens with conductive ink.

Would it not be easier to do this by hand? Or perhaps
ask the gang on the Classic Computers mailing list
(classiccomp.org) if anyone has a ZX81 keyboard
(or entire system) they can sell you?

Absolutely! Unless you are going into the business of
repairing these keyboards (doesn't seem like much of
a market), trying to get sufficient conductive path using
ANY kind of plotter-driven pen is W-A-Y more trouble
than it is worth. Unless you just like difficult projects.
Otherwise, there are MUCH easier ways of repairing
the traces.

I seriously doubt whether there is ANY viable solution
for re-creating these kinds of traces with any kind of a
pen that could be used in a plotter. And then there is the
matter of how you cause the substrate to be driven
through the grit-wheel Y-axis rollers (and thin slot).
Even if you were using a flat-bed plotter, it does not
seem practical to me.

 

[Sofie]

Peter de Vroomen:
There has to be a ":ton" of these old computers out there at EBay, thrift
stores, garages sales, etc. You can probably buy the entire computer
including the keyboard for much less than a conductive pen.
I just went to the EBay site and typed in zx81 and found dozens of hits.....
many quite cheap.

 

[Pankajkumar Chauhan]

I have been thinking of buying one of these, shortening it, and see if I can
get it to fit the plotter .


I know. For screen printing I would have to get the whole setup first
(darkroom, fotographic transfer stuff, chemicals, whatever else is needed).
It is an option, but using a plotter, I could let the plotter draw the
design. It is as reproductible (is this a good English word?) as
screen-printing, but easier to set up. And the fumes from the silver paint
won't get to too high levels .


Well, I'd *like* to. One of the connection tabs on the keyboard is ripped,
so I have to either make up a new tab or replace the whole layer. I'd rather
replace the complete layer if it is feasible.


Yep, it can be found on the internet easily. I want to try to restore the
ZX81 to it's original state. The looks of the ZX81 are very good, the
keyboard is undamaged, except some stupid fool ripped (no seriously, it
wasn't me ) a complete tab off the keyboard.

Hello

Can you let me know the status of your ZX81? I have a ZX80 with a
similar problem. The two connecting ribbons from the keyboard layer
to the mainboard have cracked plastic, which took all the conducting
channels with it.

 

[Peter de Vroomen]

And then there is the

matter of how you cause the substrate to be driven
through the grit-wheel Y-axis rollers (and thin slot).

Yep, I was so focused on the conductive ink issue that I forgot that my
HP7475 is not a flatbed plotter, which means that most of the paint on the
plastic would end up on the rubber roller . It might work with a flatbed
plotter, though. The good thing about using a plotter is that I can
reproduce the keyboard membrane whenever I want. If I'd use screen-printing,
I'd have to do complete runs.

Anyhow, one of the problems is that of the keyboard I have one of the
connector slips was ripped of and vanished somewhere in the past. So I'd
have to reconstruct that first, i.e. glue a piece of plastic overhead sheet
onto the remains and try to get the traces on there. But the point where the
pieces are glued together are unstable and would probably not last very
long.

PeterV

 

[Peter de Vroomen]

I just went to the EBay site and typed in zx81 and found dozens of
hits.....

many quite cheap.

Don't be fooled: most of these either have an external keyboard or have an
intermittent keyboard. I am simply trying to get a ZX81 that's completely
standard and works flawless (as far as ZX81's can work flawless ). Only
maybe 1 out of 15 ZX81's still have a solid working original keyboard.

PeterV

 

[mike]

Hi,

I am looking for plotter pens (HP7475 compatible) or inkjet cartridges that
can paint electrically conductive lines on transparent plastic sheets. I
need this to repair the keyboard membrane of my old ZX81 computer .

Has anyone ever encountered something like this?

PeterV

I fixed a laptop keyboard with conductive silver ink.
The problem was viscosity. I couldn't make it stay where it needed to
be. Ended up putting masking tape over the area and cutting channels
in it with an Xacto knife. Then could dribble the silver stuff into
the channel. The tape held it where it needed to be. Had to experiment
with when to remove the tape. Too early and the ink runs. Too late and
it pulls off the silver stuff. Still had to scrape out the shorts.
But it worked. Fixed a $1 laptop with a $15 bottle of silver ink.
Won't make that mistake again.
mike

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[Michael Buchholz]

I am looking for plotter pens (HP7475 compatible) or inkjet cartridges that
can paint electrically conductive lines on transparent plastic sheets. I
need this to repair the keyboard membrane of my old ZX81 computer .

Hi!

If You happen to have access to a CNC mill or (better) a dispenser robot
for SMT glue, I would go this way, and get a syringe full of silver
paint
(this crap is like honey, no way to draw it at the speed a Plotter woud
go)
mounted instead of the milling tool.

If the plotter is Speed-adjustable, get a small syringe, fill it with
the
Stuff, cut the Neddle flat with a Dremel, and try it without the
plunger.

Michael Buchholz.

P.S.: sorry if I misspelled something, I'm not a native speaker...