Favourite parts with off-label uses?

On 2020-04-11, dagmargoodboat@yahoo.com <dagmargoodboat@yahoo.com> wrote:

> LACQUER
> I found the technical data sheet, available on this page:
> https://www.rustoleum.com/product-catalog/consumer-brands/specialty/lacquer-spray/
>
> The operative info from that .PDF:
>   Resin Type: Acrylic Lacquer
>   Pigment Type: Proprietary
>   Solvents: Acetone, Methyl Ethyl Ketone, Toluene
>
> It doesn't list alcohol as a solvent, but 90% IPA works like a beast.

alcohol is soluble in acrylic, and tends to soften acrylic paints.

>   UPDATE: apparently Rustoleum has changed the formulation of their
>   lacquer and it no longer dissolves in alcohol!!! The last 2 cans i
>   bought have been extremely difficult to work with, which might
>   explain some of the difficulty some of you were having duplicating
>   my results. I will update further with a substitute transfer base
>   soon. Thanks!
></quote>

"Zinsser B-I-N" is shellac based and has an alcohol solvent, I have
purchased it in spray cans in the past. it contains a white pigment.

-- 
  Jasen.

On Tue, 7 Apr 2020 07:55:27 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

>On 2020-04-06 21:35, jlarkin@highlandsniptechnology.com wrote:
>> On Mon, 6 Apr 2020 17:43:46 -0400, Phil Hobbs
[snip]
>> 
>> I guess the seive would soak up humidity and reduce the pressure
>> inside, so a tiny flow through the seals would introduce a little more
>> humidity. Wouldn't that eventually get to zero humidity and zero
>> pressure differential?
>> 
>> I guess atmospheric changes would still pump the system slightly.
>
>Simon's the seal expert at this point.  A sufficiently stiff box, with 
>enough screws holding the lid on, and hermetic connectors, ought to be 
>able to stay sealed pretty well.  The pressure changes are nontrivial 
>though--our box is about 3 x 5 inches, so a 7% pressure change amounts 
>to about 15 pounds over the surface of the lid.  They're also fairly 
>slow, so it doesn't take much of a leak rate to equalize the pressure.
>
>We're using a cable gland rather than a hermetic connector, primarily 
>for cost reasons.  I suspect that enough air will flow inside the cable 
>to manage the vent job, but we'll probably have to measure that to find out.

A traditional alternative is a long thin tube whose volume is
sufficient to ensure that no inside air gets out or outside air gets
in, despite the +/- 7% variation in ambient air pressure.  Invented by
Louis Pasteur in 1859.

.<https://en.wikipedia.org/wiki/Swan_neck_flask>


Joe Gwinn

On 2020-04-11, Clifford Heath <no.spam@please.net> wrote:
>
> Acrylic, thanks. I had no idea that IPA would attack it but not lift 
> toner. That's good to know, I'll give it a try. I'll have to find 
> suitable local products, as the ones you mention don't ship to Australia.

The "Export" brand paints available in Supercheap Auto are really
crappy, they claim to be enamel paint but seem to never actually cure
and always dissolves in mineral turpentine.

Supercheap also have 3M, Septone, and "SCA" brand "Acrylic" lacquer sprays.  
As these paints are intended for automotive use they are probably alcohol
resistant due to the introduction of alcohol in fuel.

They also have SCA brand "multi purpose" Acrylic paint, this stuff will
possibly be softened by alcohol.  Plasti-Kote and Dulux brand acrylic
spray paints from a hardware shop are probably worth a try too.

> I could try shellac, I have some flakes here. It's intrinsically more 
> variable though, being a natural product; the water content and age are 
> factors in using it for French polish. And it doesn't come in a 
> convenient spray can.

"Zinsser B-I-N" is a commercialy produced shellac based primer.  Spray cans
are available (but can be hard to find). Alternatively some places can put 
paint into a spray can for you.

-- 
  Jasen.

On 2020-04-11, Ricky C <gnuarm.deletethisbit@gmail.com> wrote:
> On Saturday, April 11, 2020 at 1:00:09 AM UTC-4, dagmarg...@yahoo.com wrote:
>> On Friday, April 10, 2020 at 8:19:13 PM UTC-4, Clifford Heath wrote:
>> > On 9/4/20 9:39 am, dagmargoodboat@yahoo.com wrote:
>> > > I haven't been able to get toner transfer working since I changed
>> > > toner carts. But I've dabbled with two promising variations.
>> > > 
>> > > 1) If you lacquer-coat the PCB *then* transfer the toner, the
>> > > lacquer fills in the toner's pores.
>> > 
>> > James,
>> > 
>> > What exactly is the stuff that Americans call lacquer? That's not a term 
>> > that has a single meaning here.
>> 
>> I'm not completely sure. I believe it might be shellac, made from
>> actual shells of actual lac bugs?  
>
> I thought it was the shells too, but it's a secretion they leave on tree branches.  So I guess they don't kill the bugs but harvest their secretions more like silkworms. 

Actually, the silkworms don't survive harvest.  Anyway it's a secretion from a
parasite, so its probably mostly resin...  you could try pre-coating with liquid
flux or OSP.

-- 
  Jasen.

>A traditional alternative is a long thin tube whose volume is 
>sufficient to ensure that no inside air gets out or outside air gets 
>in, despite the +/- 7% variation in ambient air pressure.  Invented by 
>Louis Pasteur in 1859.

Thanks, that's an interesting idea.(*) Riding on a big-ass harvester in E Texas ot Australia or some such place, it's fairly hard to ensure that rain or wash water never gets in, though. 

Cheers

Phil Hobbs

(*) I have a lot of respect for the giants of the past--long ago, after I'd submitted my first and (so far) only theoretical paper, I withdrew it after finding that its main result had been published by Lord Rayleigh. One of my less merciful friends asked me, "How does it feel to be on the forefront of 19th century science?"  

søndag den 12. april 2020 kl. 02.47.02 UTC+2 skrev pcdh...@gmail.com:
> >A traditional alternative is a long thin tube whose volume is 
> >sufficient to ensure that no inside air gets out or outside air gets 
> >in, despite the +/- 7% variation in ambient air pressure.  Invented by 
> >Louis Pasteur in 1859.
> 
> Thanks, that's an interesting idea.(*) Riding on a big-ass harvester in E Texas ot Australia or some such place, it's fairly hard to ensure that rain or wash water never gets in, though. 
> 
> Cheers
> 
> Phil Hobbs
> 
> (*) I have a lot of respect for the giants of the past--long ago, after I'd submitted my first and (so far) only theoretical paper, I withdrew it after finding that its main result had been published by Lord Rayleigh. One of my less merciful friends asked me, "How does it feel to be on the forefront of 19th century science?"

I seem to reading that probably around the same time period, there was a saying:
"If you think you have invented some new you need to learn to read German"

On Sat, 4 Apr 2020 17:49:18 -0700 (PDT), pcdhobbs@gmail.com wrote:

>Following up on blocher's sterling work,(*)
>
>Many of us use parts off-label, often very successfully. A few examples:
>
>SAV-551+ pHEMTs make very good wideband bootstraps. Their f_max is around 12 GHz, but they're amazingly stable. 
>
>74HC4352s make good flying-capacitor diff amp front ends.
>
>TMUX1511s make very nice analogue lock-ins--their Coff*Ron FOM is almost in a class with relays, but 1E5 times faster. 
>
>Zero-ohm jumpers have about the right resistance to stabilize LDO regulators with ceramic output caps. (It's good to be able to disconnect the supplies during bring-up, and putting the jumper between the reg and the output cap has this additional benefit. 
>
>Your faves?
>
>Cheers 
>
>Phil Hobbs 
>(*) who may be bulegoge's good twin, given the similarity of their emails ;)



What a great subject !!

Kind of like off use of drugs for treating other diseases !

boB

On Saturday, April 11, 2020 at 1:29:23 PM UTC-4, Lasse Langwadt Christensen wrote:
> lørdag den 11. april 2020 kl. 19.16.51 UTC+2 skrev dagmarg...@yahoo.com:
> > On Saturday, April 11, 2020 at 3:21:43 AM UTC-4, Clifford Heath wrote:
> > > On 11/4/20 4:10 pm, dagmargoodboat@yahoo.com wrote:
> > > > On Saturday, April 11, 2020 at 1:00:09 AM UTC-4, dagmarg...@yahoo.com wrote:
> > > >> On Friday, April 10, 2020 at 8:19:13 PM UTC-4, Clifford Heath wrote:
> > > >>> On 9/4/20 9:39 am, dagmargoodboat@yahoo.com wrote:
> > > >>>> I haven't been able to get toner transfer working since I changed
> > > >>>> toner carts. But I've dabbled with two promising variations.
> > > >>>>
> > > >>>> 1) If you lacquer-coat the PCB *then* transfer the toner, the
> > > >>>> lacquer fills in the toner's pores.
> > > >>> James,
> > > >>>
> > > >>> What exactly is the stuff that Americans call lacquer? That's not a term
> > > >>> that has a single meaning here.
> > > >>
> > > >> I'm not completely sure. I believe it might be shellac, made from
> > > >> actual shells of actual lac bugs?  The important property here is
> > > >> that it's alcohol-soluble. You might be able to vet local products
> > > >> by checking the clean-up solvents spec'd.
> > > >>
> > > >> This is what I tried & recommend --
> > > >> https://www.homedepot.com/p/Rust-Oleum-Specialty-11-oz-Gloss-White-Lacquer-Spray-Paint-1904830/100163605
> > > >>
> > > >> I recommend white, as contrasting brilliantly with the black toner.
> > > >>
> > > >> It's easily removed with 90% isopropyl alcohol, leaving printer toner
> > > >> completely unaffected. Toner scoffs at IPA.
> > > 
> > > 
> > > Acrylic, thanks. I had no idea that IPA would attack it but not lift 
> > > toner. That's good to know, I'll give it a try. I'll have to find 
> > > suitable local products, as the ones you mention don't ship to Australia.
> > 
> > I think you missed a note in there -- they've changed the product.
> > The original (that worked) was shellac(?), but it has been changed
> > to a new formula that allegedly does not work as well.
> > 
> > Ammonia strips acrylic floor wax, so maybe it would strip an acrylic
> > undercoating, if acrylic is all we can get.
> > 
> > I don't know which Rust-Oleum formula I got.  Whatever's in my
> > two-or-three-years-old can of the stuff works wonderfully. It wipes
> > off the open surfaces readily with 90% alcohol(*), but stays in the
> > toner's pores, sealing them.
> > 
> > (*) 50% IPA was unsatisfactory.
> > 
> > > I could try shellac, I have some flakes here. It's intrinsically more 
> > > variable though, being a natural product; the water content and age are 
> > > factors in using it for French polish. And it doesn't come in a 
> > > convenient spray can.
> > > 
> > > >>>> The toner image is printed on the paper you peel off the back of
> > > >>>> adhesive labels, or in my case, backing peeled off adhesive
> > > >>>> shelf-liner paper from the one-dollar store.
> > > >>>
> > > >>> I tried things like that but they were too slippery - bits of toner just
> > > >>> fell off before getting transferred. I'm using toner transfer paper
> > > >>> bought for the purpose.
> > > >>
> > > >> I had that experience early on, years ago. But the current label-
> > > >> backing type paper didn't have that problem.  It's truly a godsend;
> > > >> no more rubbing, soaking and peeling, hoping the toner sticks.
> > > 
> > > The paper I use has a significant starch (I think) content, and wets 
> > > really quickly - like 10 seconds before it comes off cleanly. The only 
> > > other relevant factor is how much it slows down the heat transfer in the 
> > > laminator; even after proper pre-warming I pass it through 2 or 3 times.
> > > 
> > > >> Transferring to a lacquer-coated board might be easier.  The lacquer
> > > >> is infinitely grabbier than even roughed up copper.
> > > 
> > > Good to know.
> > > 
> > > 
> > > > BACKING PAPER
> > > > This gent  illustrates my joyous experience printing onto backing paper,
> > > > and the ease of transfer--the toner just comes right off, eliminating
> > > > a wet step.  He uses the paper he peels off Arlon vinyl.
> > > >    https://www.youtube.com/watch?v=haqP8xhsYas
> > > > 
> > > > These are the labels whose baking paper is salvaged and used by
> > > > the gentleman in the first of those YouTubes above--
> > > > 
> > > > Best PRINT half-sheet labels (1/2 page-sized labels)
> > > >    https://www.amazon.com/Best-Print-200-Half-Sheet/dp/B0069RY9BY
> > > > 
> > > > The big lure of backing paper to me was eliminating the process
> > > > variations of thermally transferring toner to copper from paper.
> > > > The backing paper goes a long way toward accomplishing that.  I
> > > > still have trouble getting adhesion to bare copper.
> > > > 
> > > > 
> > > > Overall, this ability to use two different resist coatings (toner and
> > > > lacquer) that dissolve in different solvents feels full of
> > > > promise & possibilities...
> > > 
> > > Well, after all, this is only for Saturday afternoon prototyping at RF.
> > 
> > Yes, exactly.  I've designed a class-C HF QRP PA using CMOS gates
> > that might see first power this way. LTSpice says it's about 80%
> > efficient, ideally, from d.c. input power to 50-ohm load.
> > 
> > > Other prototypes can be on assorted grid boards that don't provide a 
> > > ground plane, and anything more permanent can go through one of the many 
> > > quick-turn board houses.
> > > 
> > > A friend uses a modified record-player to spin photoresist onto boards, 
> > > and makes double-sided boards quite frequently, but the process took a 
> > > lot of work to perfect.
> > 
> > Yep.  The dry photo resist film method looks easier than spincoating,
> > but I'd really like to _reduce_ the wet steps and process variables.
> > https://www.instructables.com/id/Photoresist-Dry-Film-a-New-Method-of-Applying-It-t/
> >  
> > > There's something about knocking up a schematic in Kicad, laying it on a 
> > > board, and soldering it up an hour after you started. Sometimes the 
> > > magic flows and you want to try something *now*.
> > 
> > There sure is something magical about it and that's exactly why I do
> > it.  It's liberating.
> > 
> > Frankly I'd still be using unmodified toner transfer if it hadn't
> > quit on me.  Previously I was making 0.012" traces and spaces with ease.
> > I had no problems at all, worked every time without trouble, and I
> > wondered what everyone else was griping about.  But once it quit,
> > no amount of fiddling has gotten it working again.  Same papers,
> > same printer, same clothes iron, etc., but no joy.
> > 
> > My problem is getting the toner to adhere to the copper.  I had the same
> > difficulty transferring thermally, and with the cold transfer (solvent)
> > methods that rely on making the toner sticky--the darn toner just won't
> > stick to the board. But I must say toner sticks very aggressively to a
> > sticky lacquered board, whether I use heat or solvents to soften the
> > lacquer and make it sticky.
> > 
> 
> tried a quick dip in etchant before the transfer?
> 
> a few seconds and the copper turns a more dull rough surface

Yes, thanks, I've tried a quick dip to roughen the copper surface,
but it didn't make any difference.  It's mysterious.

When TT was working, I prepared the copper with fine steel wool,
then sometimes Comet (an abrasive kitchen cleaner with soap and bleach)
for de-greasing.  I've the original method, rough sandpaper, fine
sandpaper, cross-hatching, and etching.

Cheers,
James Arthur

On Saturday, April 11, 2020 at 5:32:53 PM UTC-4, Jasen Betts wrote:
> On 2020-04-11, dagmargoodboat@yahoo.com <dagmargoodboat@yahoo.com> wrote:
> 
> > LACQUER
> > I found the technical data sheet, available on this page:
> > https://www.rustoleum.com/product-catalog/consumer-brands/specialty/lacquer-spray/
> >
> > The operative info from that .PDF:
> >   Resin Type: Acrylic Lacquer
> >   Pigment Type: Proprietary
> >   Solvents: Acetone, Methyl Ethyl Ketone, Toluene
> >
> > It doesn't list alcohol as a solvent, but 90% IPA works like a beast.
> 
> alcohol is soluble in acrylic, and tends to soften acrylic paints.
> 
> >   UPDATE: apparently Rustoleum has changed the formulation of their
> >   lacquer and it no longer dissolves in alcohol!!! The last 2 cans i
> >   bought have been extremely difficult to work with, which might
> >   explain some of the difficulty some of you were having duplicating
> >   my results. I will update further with a substitute transfer base
> >   soon. Thanks!
> ></quote>
> 
> "Zinsser B-I-N" is shellac based and has an alcohol solvent, I have
> purchased it in spray cans in the past. it contains a white pigment.
> 
> -- 
>   Jasen.

Thanks Jasen, very helpful. That should set Clifford on the right track.

Cheers,
James Arthur

Am 12.04.20 um 07:05 schrieb dagmargoodboat@yahoo.com:
> On Saturday, April 11, 2020 at 1:29:23 PM UTC-4, Lasse Langwadt Christensen wrote:
(and others)

so much about problems and possible solutions that my mailer
would reject the post for excessive quoting..



The more I read here, the more I'm convinced to stay with the
photochemical priciple. The boards are cleaner than one could
ever hope to clean them oneself, surfaces lapped and covered
with photo resist and then protection foil.

All one needs is a UV source (face tanner in my case), NaOH
as developper and stripper, the etchant, Na- or Ammonium-
persulfate and two sheets of glass to enforce direct contact
between the film and the board during exposure.

I can easily produce anything my laser printer can print, easily
down to 4 mil / 4 mil feature size with offset film.
The process takes less than an hour from the time I've printed
the film and is absolutely reproducible.

I use their board material:
< 
https://www.bungard.de/shop/index.php/de/fotobeschichtetes-basismaterial 
      >
but not their machines. There must be similar offers on other
continents.

And yes, I also use PCBway and others when there is time and
willingness to deal with DHL and our customs office
who question the price of the boards on a regular base.
That cheap, absolutely impossible! Fraud!

cheers, Gerhard