Homebrew PCBs

Saw a novel use for PCBs yesterday on Mythbusters.

They had to get past a fingerprint lock.

The way they did it was lift a fingerprint, scan it, touch it up, etch
a PCB from the image, and then cast latex or gelatine over it to make
a 3D finger.

It worked! The simple PC lock was fooled by it, when it did not take a
simple printout on paper. The supposedly advanced door lock was even
fooled by the paper print, once it was licked to simulate the
conductivity.

Shows how simple these locks are to fool. I mean, come on, using a key
that leaves an exact print of it's shape hundreds of times a day for
anyone to pick up, just crazy!

Anyway, really interesting use of a PCB to make a precise
two-and-a-half dimensional mold of the fingerprint. They used
photoprocess by the way, and FeCl.

ST

At 3:14 am ((PDT)) Mon Sep 24, 2007, Stefan Trethan wrote:

>Saw a novel use for PCBs yesterday on Mythbusters.
>
>They had to get past a fingerprint lock.
>
>The way they did it was lift a fingerprint, scan it, touch it up, etch
>a PCB from the image, and then cast latex or gelatine over it to make
>a 3D finger.

>[snip] They used photoprocess by the way, and FeCl.

If they had used something like gelatine-dichromate, they could
probably have omitted the copper etch by producing a relief
direct in gelatine. A tanning developer and gelatine removal is also
a way of making artistic (and very durable) photo prints.


Regards, LenW

In a message dated 9/24/2007 4:01:20 P.M. Eastern Daylight Time,  
novost@... writes:

If  they had used something like gelatine-dichromateIf  they 
probably  have omitted the copper etch by producing a relief
direct in gelatine. A  tanning developer and gelatine removal is also
a way of making artistic  (and very durable) photo prints.

Regards, LenW  



I hope you use your knowledge for good and not evil.  :)
 
Jen



************************************** See what's new at http://www.aol.com


[Non-text portions of this message have been removed]

I didn't know there is such a thing, and they probably also went with
what they already knew. But i don't doubt there are better ways to
make those fake fingers.

What was really amazing is that the printout on paper worked on the
good quality lock which has "never been defeated" according to the
manufacturer. I mean that takes 10 minutes with a simple office
scanner and printer, and you can probably find the fingerprints you
need to copy close by.

It was also interesting to see which tricks worked on the ultrasonic
and IR motion detectors, but none involved a PCB.

If you think about it, carrying a RFID key, keycard, or even a simple
barcode tag would be safer than a fingerprint lock.

ST

On 9/24/07, Len Warner <novost@...> wrote:

>
> If they had used something like gelatine-dichromate, they could
> probably have omitted the copper etch by producing a relief
> direct in gelatine. A tanning developer and gelatine removal is also
> a way of making artistic (and very durable) photo prints.
>
>
> Regards, LenW
>
>

>
>It was also interesting to see which tricks worked on the ultrasonic

You can read the specifications: they all are AC coupled with poor 
response at very low frequency.
slow movement

>and IR motion detectors,

slow movement or thermal isolation (can use a cardboard)

>  but none involved a PCB.

no, but everyone is interested in security


>If you think about it, carrying a RFID key, keycard, or even a simple
>barcode tag would be safer than a fingerprint lock.

right

At 2:14 pm ((PDT)) Mon Sep 24, 2007, Jennynj1975 wrote:
>
>In a message dated 9/24/2007 4:01:20 P.M. Eastern Daylight Time,
>novost@... writes:
> >If  they had used something like gelatine-dichromate [snip]
>
>I hope you use your knowledge for good and not evil.  :)

I blame Stefan Trethan.

Ever since he introduced me to sniffing ammonia bottles
my view of the world has been distorted
(but my mind has seemed much clearer).


Regards, LenW

In a message dated 9/25/2007 10:08:02 A.M. Eastern Daylight Time,  
novost@... writes:

Ever  since he introduced me to sniffing ammonia bottles
my view of the world has  been distorted
(but my mind has seemed much  clearer).


LOL! That is the best.  I joined this group to really study the  Chemistry 
behind the whole process.  I am a BSChem.  The husband is  the BSEE.  We've been 
into the PCBs for a little while now, but nothing  really serious.  He is the 
designer and I, the maker of the Boards.   Mostly just for fun, but we are 
trying to expand on our work to make some  money.  :)
 
Nice to see the group is a little chatty.  
 
So what's everyone's backgrounds and interest in making PCBs?  
 
Jen



************************************** See what's new at http://www.aol.com


[Non-text portions of this message have been removed]

Jennynj1975@... writes:
> So what's everyone's backgrounds and interest in making PCBs?  

Hmmm... I've beem making boards at home on and off since, um, the
early 80's?  I was in high school at the time, maybe younger.  Back
then I used the press-on decals and pen, now I use toner transfer.

I make my own boards when I want it quickly and/or quality doesn't
matter enough to warrant sending it out, or when I feel like it
(making the boards is part of the fun!).  Usually, it's for test
circuits, adapters, or anything so simple that it can be done without
too many vias.  The last set I made each just held a couple of
pushbutton switches at the right spots behind moving bits.  I.e. the
PCB was more mechanical than electrical.

I've also done many smt to breadboard adapters, for parts I want to
experiment with that don't come in breadboard-compatible packages.

And for reference, the most complex board I've ever designed and had
fabbed was a 386SX PC/AT motherboard.  Yes, it worked :-) I worked at
Data General back then, designing motherboards and writing BIOS code.
Now I work at Red Hat, writing embedded development tools, so I get to
play with hardware a bit still.

The simplest was a SOT-23 adapter for my breadboard.

On Tue, 25 Sep 2007 13:54:50 EDT, you wrote:

> 
>In a message dated 9/25/2007 10:08:02 A.M. Eastern Daylight Time,  
>novost@... writes:
>
>Ever  since he introduced me to sniffing ammonia bottles
>my view of the world has  been distorted
>(but my mind has seemed much  clearer).
>
>
>LOL! That is the best.  I joined this group to really study the  Chemistry 
>behind the whole process.  I am a BSChem.  The husband is  the BSEE.  We've been 
>into the PCBs for a little while now, but nothing  really serious.  He is the 
>designer and I, the maker of the Boards.   Mostly just for fun, but we are 
>trying to expand on our work to make some  money.  :)
> 
>Nice to see the group is a little chatty.  
> 
>So what's everyone's backgrounds and interest in making PCBs?  

www.dragonworks.info the electronics sections in particular.

Harvey

> 
>Jen
>
>
>
>************************************** See what's new at http://www.aol.com
>
>
>[Non-text portions of this message have been removed]

> >It was also interesting to see which tricks worked on the ultrasonic
> 
> You can read the specifications: they all are AC coupled with 
> poor response at very low frequency.
> slow movement
> 
> >and IR motion detectors,
> 
> slow movement or thermal isolation (can use a cardboard)
> 
> >  but none involved a PCB.
> 
> no, but everyone is interested in security


They defeated the ultrasonic detector by simply holding a sheet (as in one
off your bed) in front of them, and walked at a normal pace.  (Might have
been a blanket.)  Not quite what you were thinking.

If you're think 'OMG that won't work', well, so did everyone else!  OMG, it
does!  Yes, I tried it.

One way they beat IR was to get behind a pane of glass (but I already knew
that one).  BTW, that's new glass, some really old glass will pass IR.
Rather than walk around holding up a sheet of glass, they put a small piece
on a rod, and hung it over the detector.  That was actually quite clever.

I recall a documentary once where the thieves beat the IR detectors in a
warehouse by building a wall of boxes (TVs fridges etc), like you said.
Once the wall was high enough they could do what they pleased behind it.
They knew the building layout though.

Where I once worked had an IR sensor that unlocked the door when you were
leaving (so you didn't have to press a button).  I didn't have my pass one
day, so I slid a piece of metal that had been lying in the sun under the
door.

Cool doors, glass with electromagnets to hold them closed.

Tony

"Tony Smith" <ajsmith@...> writes:
> Cool doors, glass with electromagnets to hold them closed.

I asked about the magnets once.  It's a fire code thing; the doors
automatically unlock in the event of fire or power loss, just because
the magnets stop working.  With a "power open" lock, people might get
trapped in a burning building.

At 08:25 PM 9/26/2007, you wrote:


>"Tony Smith" 
><<mailto:ajsmith%40rivernet.com.au>ajsmith@...> writes:
> > Cool doors, glass with electromagnets to hold them closed.
>
>I asked about the magnets once. It's a fire code thing; the doors
>automatically unlock in the event of fire or power loss

they usually use accus as a back-up power supply

>, just because
>the magnets stop working. With a "power open" lock, people might get
>trapped in a burning building.
>


[Non-text portions of this message have been removed]

At 05:54 PM 9/26/2007, you wrote:
>They defeated the ultrasonic detector by simply holding a sheet (as in one
>off your bed) in front of them, and walked at a normal pace. (Might have
>been a blanket.) Not quite what you were thinking.

And what about the multiple reflection paths?

> One way they beat IR was to get behind a
> pane of glass (but I already knew that
> one).  BTW, that's new glass, some
> really old glass will pass IR.
>
> Rather than walk around holding up a
> sheet of glass, they put a small piece
> on a rod, and hung it over the detector.
> That was actually quite clever.
> 
> I recall a documentary once where the
> thieves beat the IR detectors in a
> warehouse by building a wall of boxes
> (TVs fridges etc), like you said.  Once
> the wall was high enough they could do
> what they pleased behind it.
>
> They knew the building layout though.

Freezer suits will give you a few minutes
immunity to IR detectors.  Just long enough
to put it on, run around with some paper
and sticky tape and cover all the sensors
up.

Mostly I make pcb's on the hobby side. Some RF stuff (I'm a HAM), some
fun things, lots of test type equipment. The pcb's are way easier and
a lot more fun to make than hand wiring. I like toner transfer since
it's easy. I can draw a schematic, lay down a board, etch it and
populate it faster than I can hand wire and I can use parts that are
way more sophisticated in the TQFP packages. I'll also use the photo
method but I always head for Toner Transfer first. Lately I've also
been laying out and etching proto-types and one-off's for work. Way
cheaper and then I get to do the layout myself. Like you, I'm getting
better at it and I might try to sell a few of my designs (whole
finished units, proto-type design, custom test equipment, ect.)

Only problem is ... so many projects, so little time. :-)
Phil (KA0HBG)


> I joined this group to really study the  Chemistry 
> behind the whole process.  I am a BSChem.  The husband is  the BSEE.
 We've been > into the PCBs for a little while now, but nothing 
really serious.  He is the > designer and I, the maker of the Boards.
  Mostly just for fun, but we are > trying to expand on our work to
make some  money.  :)
>  
> Jen

> At 05:54 PM 9/26/2007, you wrote:
> >They defeated the ultrasonic detector by simply holding a 
> sheet (as in 
> >one off your bed) in front of them, and walked at a normal 
> pace. (Might 
> >have been a blanket.) Not quite what you were thinking.
> 
> And what about the multiple reflection paths?


What multiple reflection paths?  Bounce of the wall behind the person, hit
the person, bounce back to the wall and back to the sensor?  Right.

I guess that means you take two blankets.

Tony

> > I recall a documentary once where the
> > thieves beat the IR detectors in a
> > warehouse by building a wall of boxes
> > (TVs fridges etc), like you said.  Once the wall was high 
> enough they 
> > could do what they pleased behind it.
> >
> > They knew the building layout though.
> 
> Freezer suits will give you a few minutes immunity to IR 
> detectors.  Just long enough to put it on, run around with 
> some paper and sticky tape and cover all the sensors up.


Mythbusters tried that too.  Didn't work all that well, by the time they
stuffed about getting the suit on it had heated up.  Then there was the
problem with the face plate...

With enough enthusiam it could be made to work.

Maybe you could just freeze a blanket, held in front of you that'd take care
of both IR & ultrasonic sensors.  You can put it top of the razor wire when
scaling the fence, around your arm when smashing the window, and over the
guard dog when it shows up.

Blankets.  Is there anything they can't do?

Tony

> > > Cool doors, glass with electromagnets to hold them closed.
> >
> >I asked about the magnets once. It's a fire code thing; the doors 
> >automatically unlock in the event of fire or power loss
> 
> they usually use accus as a back-up power supply


Accus?

Tony

In article <20070929153212.911DB36E6A8@...>,
   Tony Smith <ajsmith@...> wrote:
> Accus?

I would guess at accumulators - as in lead-acid - batteries

> > Accus?
> 
> I would guess at accumulators - as in lead-acid - batteries


Gosh, do people still call them that?

Tony

> Tony Smith wrote:
> 
> <SNIP>
> Maybe you could just freeze a blanket, held
> in front of you that'd take care of both IR
> & ultrasonic sensors.  You can put it top
> of the razor wire when scaling the fence,
> around your arm when smashing the window,
> and over the guard dog when it shows up.
> 
> Blankets.  Is there anything they can't do?

isn't it towels ?

There is a hoopy frood that really knows wher
his blanket is.

Does not quite work.

> > Maybe you could just freeze a blanket, held in front of you that'd 
> > take care of both IR & ultrasonic sensors.  You can put it 
> top of the 
> > razor wire when scaling the fence, around your arm when 
> smashing the 
> > window, and over the guard dog when it shows up.
> > 
> > Blankets.  Is there anything they can't do?
> 
> isn't it towels ?
> 
> There is a hoopy frood that really knows wher his blanket is.
> 
> Does not quite work.


You're absolutely right.

Sucking tea from the corner of a blanket after (or even during) a successful
break-in would be just wrong, a towel it is.

Tony

In a message dated 9/29/2007 1:16:23 P.M. Eastern Daylight Time,  
ajsmith@... writes:

>  > Accus?
> 
> I would guess at accumulators - as in lead-acid -  batteries

Gosh, do people still call them  that?

Tony


I have never heard that term before, you are referring to car  batteries?
 
Jen



************************************** See what's new at http://www.aol.com


[Non-text portions of this message have been removed]

> >  > Accus?
> > 
> > I would guess at accumulators - as in lead-acid -  batteries
> 
> Gosh, do people still call them  that?
> 
> Tony
> 
> 
> I have never heard that term before, you are referring to car 
>  batteries?
>  
> Jen


It's a very old term, certainly older than cars!  I haven't heard it for
years.

It means anything that'll store a charge, such as lead-acid car batteries.
Capacitors used to be called accumulators as well.  I'm not sure when it
died out, but it'd be rare to see it in post-WWII writings.

I was surprised to see someone use it, next we'll be hearing about the
aether (luminous or otherwise).

Tony

It's used in german for any rechargeable battery, that's why it hasn't
gone away completely.

ST

On 9/30/07, Tony Smith <ajsmith@...> wrote:
> > >  > Accus?
> > >
> > > I would guess at accumulators - as in lead-acid -  batteries
> >
> > Gosh, do people still call them  that?
> >
> > Tony
> >
> >
> > I have never heard that term before, you are referring to car
> >  batteries?
> >
> > Jen
>
>
> It's a very old term, certainly older than cars!  I haven't heard it for
> years.
>
> It means anything that'll store a charge, such as lead-acid car batteries.
> Capacitors used to be called accumulators as well.  I'm not sure when it
> died out, but it'd be rare to see it in post-WWII writings.
>
> I was surprised to see someone use it, next we'll be hearing about the
> aether (luminous or otherwise).
>
> Tony
>
>
>
> Be sure to visit the group home and check for new Links, Files, and Photos:
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