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Charge needed to disable a car ?

S

Sonco

Jan 1, 1970
0
A friend said that a high voltage charge applied to the body would disable ,
shut off a running car. Is this possible ? also if it would work would it
also work on an older pre electronic ignition car ?

Thanks
 
J

JohnR

Jan 1, 1970
0
Greg said:
Nope. If you have points and a coil I doubt the EMP shot from a nuke would stop
the car. It might blow the radio but that is about it.

I bet the electronics in a new car are a lot tougher than they would have you
believe too. I doubt getting hit by lightning would stop one.
I have seen them hold up to the ignition cables getting away and sparking
around the engine compartment.

I'd agree, but I've seen car disabling devices that will stop a car when it
is driven over. A wire sticks up and you can see a spark as the car passes
over and is disabled. How this is accomplished I don't know.

My best guess is a high voltage capacitor is discharged. The very high
current causes a high voltage gradient around the points of contact that
knocks out the computer.

John
 
S

SQLit

Jan 1, 1970
0
Sonco said:
A friend said that a high voltage charge applied to the body would disable ,
shut off a running car. Is this possible ? also if it would work would it
also work on an older pre electronic ignition car ?

Thanks

Possible .............yes
Practical........... not yet.

The amount of voltage would be staggering. Lightning is what your talking
about, or an huge welding arc.
 
J

Jim Douglas

Jan 1, 1970
0
Probably not, if you want to stop a car check out the stuff the Iraq folks
are turning in for $$, remember this stuff was in their house.
 
W

w_tom

Jan 1, 1970
0
It is not voltage that shuts off a car. It is current AND
where that current passes. For example, it might be possible
to run hundreds or thousands of amps across the chassis and
therefore cause a few milliamps to pass through a critical
sensor or controller. But then that would be unique to each
model and unique to where the current enters and leaves the
vehicle.

This is the point. To cause a shutdown, critical function
must have both an incoming and outgoing current path. Current
- not voltage - is the critical variable. High voltage may or
may not be necessary to create that current. But how current
passes through a critical component determines whether that
vehicle can be halted.

Many think of electricity as if it was a wave crashing on
the beach. Apply a big voltage (a big wave) and that voltage
wave overwhelms the circuitry. Electricity does not work that
way as was even taught in elementary school science. First
electricity must have a complete path - both an incoming and
outgoing path though the circuitry. As the current increases
equally and everywhere in that path, only then does a control
circuit become overwhelmed and fail.

Furthermore, auto manufacturers spend significant time
planning, testing and modifying so that this will not occur.
Vehicles are even placed in anachoeic chambers to be tested
with high concentrations of radio waves at every frequency.
So yes, it is possible. But that means a unique weakness must
be discovered for that unique model.

Such problems were more common with mid and late 1970s
America cars. But then 'car guys' were no longer designing
the product. Back then, bean counters would often eliminate
such testing and design reviews to cut costs. 1979 American
vehicles were some of the highest failure products in
automotive history. The 1980s is a story of car guys again
taking over vehicle design - which is why, for example, Ford
went back to profits in the early 1990s.
 
S

Sylvia Else

Jan 1, 1970
0
Sonco said:
A friend said that a high voltage charge applied to the body would disable ,
shut off a running car. Is this possible ? also if it would work would it
also work on an older pre electronic ignition car ?

Thanks

Coincidentally, I was at the top of Mount Wellington the other day,
which overlooks Hobart, and rises to 1200m. There's a road to the top
(I'm no mountain climber). In the shelter (from the unbelievably strong
wind) there were warnings that the high radiation intensities from
transmitters located at the peak were enough to prevent the proper
operation of some cars. In particular, they could stop car security
systems from recognising the presence of the ignition key. They
suggested moving the car a bit if this happened (presumably to exploit
the intereference patterns).

But as for the original question, since the electronics are grounded to
the body, I wouldn't have thought that applying a charge to the body
would have any effect, and certainly nothing more than a transient effect.

Sylvia.

Sylvia.
 
A

Al

Jan 1, 1970
0
Sylvia Else said:
Coincidentally, I was at the top of Mount Wellington the other day,
which overlooks Hobart, and rises to 1200m. There's a road to the top
(I'm no mountain climber). In the shelter (from the unbelievably strong
wind) there were warnings that the high radiation intensities from
transmitters located at the peak were enough to prevent the proper
operation of some cars. In particular, they could stop car security
systems from recognising the presence of the ignition key. They
suggested moving the car a bit if this happened (presumably to exploit
the intereference patterns).

But as for the original question, since the electronics are grounded to
the body, I wouldn't have thought that applying a charge to the body
would have any effect, and certainly nothing more than a transient effect.

Sylvia.

In Needham, MA, there are three 1300ft transmitter towers in like a
triganular area. There are many businesses and homes beneath them. If
you live or work in the area, you are advised, when you buy a security
system, to tell the provider of your location. They provide a "special"
system which will operate in the vicinity of the towers. I learned about
that too late. When it's humid or the ground is wet, I have to put my
remote up agains my driver's side window in order to activate/deactivate
the security system. On some day, it doesn't work at all. In non-tower
areas, my remote has about a 50 ft range.

When the early ABS were installed, in some instances they would be
activated by radio transmitters at the mouths of tunnels. Nice! Why were
the transmitters there? Dunno!

I heard that some police depts were working on car disabling systems
which consist of laying a wire in the path of a car under chase. The
high voltage is supposed to zap the engine module. Some day, you will
see, the engine modules will have the capability of being disabled by
remote control. Boy will the hackers have fun with that!

And don't tell me the hackers can't do it. They have broken virtually
all systems to date.

Al

Al
 
S

Sylvia Else

Jan 1, 1970
0
Al said:
I heard that some police depts were working on car disabling systems
which consist of laying a wire in the path of a car under chase. The
high voltage is supposed to zap the engine module. Some day, you will
see, the engine modules will have the capability of being disabled by
remote control. Boy will the hackers have fun with that!

That's a somewhat different scenario. Because the underneath of the car
is not usually covered in metal, it is conceivable that an
electromagnetic field can be created that would be enough to damage the
electronics.
And don't tell me the hackers can't do it. They have broken virtually
all systems to date.

I think 'hackers' have acquired an unreasonable reputation of being able
to break into any system. In practice most attacks that do not require
the victim's unwitting cooperation have been variations on a theme -
exploitation of the buffer overflow programming error (I call it 'error'
here - what I call it in private doesn't bear repeating in polite society).

There's no good reason a car's security system shouldn't be immune to
hacking attacks. Of course, that doesn't tell us it will be. Depends
whether it's developed on the cheap.

Sylvia.
 
W

w_tom

Jan 1, 1970
0
Read an earlier post. A principle taught in elementary
school science about how electricity works:
To cause a shutdown, critical function must have both an
incoming and outgoing current path.

Apply current to the metal body or to metal that covers the
entire underside of a car. Now we have the incoming path.
But where is the outgoing path? No outgoing path - no
current. No current, then no problem.

To be completely immune to hacker attacks, then a security
system must be so secure that even an auto mechanic cannot
repair it. So secure that a locksmith cannot enter the car
when the security system fails. What is the purpose of a
security system? To keep the honest people honest.
 
O

operator jay

Jan 1, 1970
0
w_tom said:
Read an earlier post. A principle taught in elementary
school science about how electricity works:

Apply current to the metal body or to metal that covers the
entire underside of a car. Now we have the incoming path.
But where is the outgoing path? No outgoing path - no
current. No current, then no problem.

I think you'll have trouble explaining how antennas work with that theory,
or maybe even capacitors. The above principle is used very often, but in
electrostatics or e/m field situations it may not hold.

j
 
S

Sylvia Else

Jan 1, 1970
0
operator said:
I think you'll have trouble explaining how antennas work with that theory,
or maybe even capacitors. The above principle is used very often, but in
electrostatics or e/m field situations it may not hold.

Yes, this aspect bothered me too.

If you suddenly dump a collection of electrons onto one part of a car's
metal surface, there is a net electric field between that point and
every other point on the car. This field accelerates the electrons which
start spreading out along all the conducting paths. Eventually, they
have distributed themselves so that there is no (additional) electric
field along any conducting path. There will be a period of damped
oscillation until this state is reached.

Prior to the equilibrium state there are currents travelling along
conducting paths. Where the end of a path is not conducting a charge
builds up, which ultimate stops the flow (and reverses it, hence the
osciallations). But in the mean time, the charge at that point (say
somewhere in the electronic control system) may be high enough to break
the insulation in a component such as an IGFET. Bye bye control system.
The vulnerability of some such electronic components to static charges
is well documented, and is why we get them in protective conducting
bags, or on conductive foam.

So the only real question here is how much charge would you need?

Sylvia.
 
O

operator jay

Jan 1, 1970
0
Sylvia Else said:
Yes, this aspect bothered me too.

If you suddenly dump a collection of electrons onto one part of a car's
metal surface, there is a net electric field between that point and
every other point on the car. This field accelerates the electrons which
start spreading out along all the conducting paths. Eventually, they
have distributed themselves so that there is no (additional) electric
field along any conducting path. There will be a period of damped
oscillation until this state is reached.

Prior to the equilibrium state there are currents travelling along
conducting paths. Where the end of a path is not conducting a charge
builds up, which ultimate stops the flow (and reverses it, hence the
osciallations). But in the mean time, the charge at that point (say
somewhere in the electronic control system) may be high enough to break
the insulation in a component such as an IGFET. Bye bye control system.
The vulnerability of some such electronic components to static charges
is well documented, and is why we get them in protective conducting
bags, or on conductive foam.

So the only real question here is how much charge would you need?

Sylvia.

That is a tough one. When I read the original question, along the lines of
'is it possible', I can only think to myself, yeah, sure I guess it's
possible. I don't know how it would disable a vehicle, I don't even know
which component(s) it might effect. I don't know if it would be a reliable
or very unreliable method of disrupting a car's operation. In fact I kind
of have to take some liberties with the question; 'apply a high voltage
charge' is kind of funny wording.

Maybe charge rushing onto the car's body causes B fields that link some
circuit(s) and cause havoc? Doesn't seem too too likely or too dependable.

I assume that the excess charge would want to spread out as much as
possible, even to the conductive surfaces of the 'positive' side of the
electrical system, if it had a way. Maybe charge buildup on the 'negative'
side of the car's electrical system flashes across spark plug gaps. That
could mess up timing pretty bad. Maybe that could cause a stall. But it
would suck if the guy could just fire his car up again and go. I wonder
what happens at the battery. I can't see it preventing the flow of charge,
since its job is to make charge flow. Perhaps beaucoup charge flows and a
fuse thereabouts pops. If that isolated the ignition system from the
battery and the charging system, then the car would die pretty quick, and
stay dead, and not have any serious damage. After applying a charge and
disabling the car, a probe could then ground the car's frame, so that some
poor dumb bastard doesn't get zapped getting out of his dead car.

In short, I don't know, I've got nothing but some not-quite-uneducated WAGs.
I guess that's why I didn't respond earlier.

j
 
W

w_tom

Jan 1, 1970
0
Two ends of a wire - an 'antenna' - may have different
charges at either end of that wire if that wire is located in
an EM field of proper frequency and orientation. What does
this mean? We now require specific numbers. If
electromagnetic fields are applied in just the right way to
the right length wire, then we have small currents (not major
transistor destructive currents) that leave one end of the
wire and return to the other end (again the complete circuit
requirement). IOW an electromagnetic field applied to an
'antenna' that can discharge current through a circuit. But
the necessary outgoing and incoming path still required. That
'antenna' must still connect to a complete circuit that is
incoming and outgoing via electronics. A complete circuit is
still required to have current flow.

All of which is irrelevant to post that does not apply an
electromagnetic field; contains both electrical and magnetic
fields. The original question is simply about applying a high
voltage charge to car metal. There is no significant
electromagnetic field to be received by an interior
'antenna'. Furthermore a complete sheet of metal exists
between a charge located under the car and all contents inside
the vehicle - a shield against electromagnetic fields.

1) High voltage is not both electrical and magnetic fields.
2) A complete sheet of metal exists between the charge and
interior electronics - in essence faraday cage protection. 3)
Even a charge induced on an antenna by fields requires a
complete circuit out of and back into that antenna. No
complete circuit path means no current from and back into that
antenna. Connecting just one end of an antenna to electronics
does not result in a current through that electronics. A
complete circuit must first exist. Connections to both ends
of the antenna are required to create a current. Again:
To cause a shutdown, critical function must have both an
incoming and outgoing current path.

Again return to the earlier post:
It is current AND where that current passes. For example,
it might be possible to run hundreds or thousands of amps
across the chassis and therefore cause a few milliamps to
pass through a critical sensor or controller.

But again we still have that essential requirement. Both an
incoming and outgoing circuit path must exist - else no
current flow.
 
O

operator jay

Jan 1, 1970
0
w_tom said:
Two ends of a wire - an 'antenna' - may have different
charges at either end of that wire if that wire is located in
an EM field of proper frequency and orientation. What does
this mean? We now require specific numbers. If
electromagnetic fields are applied in just the right way to
the right length wire, then we have small currents (not major
transistor destructive currents) that leave one end of the
wire and return to the other end (again the complete circuit
requirement). IOW an electromagnetic field applied to an
'antenna' that can discharge current through a circuit. But
the necessary outgoing and incoming path still required. That
'antenna' must still connect to a complete circuit that is
incoming and outgoing via electronics. A complete circuit is
still required to have current flow.

All of which is irrelevant to post that does not apply an
electromagnetic field; contains both electrical and magnetic
fields. The original question is simply about applying a high
voltage charge to car metal. There is no significant
electromagnetic field to be received by an interior
'antenna'. Furthermore a complete sheet of metal exists
between a charge located under the car and all contents inside
the vehicle - a shield against electromagnetic fields.

1) High voltage is not both electrical and magnetic fields.
2) A complete sheet of metal exists between the charge and
interior electronics - in essence faraday cage protection. 3)
Even a charge induced on an antenna by fields requires a
complete circuit out of and back into that antenna. No
complete circuit path means no current from and back into that
antenna. Connecting just one end of an antenna to electronics
does not result in a current through that electronics. A
complete circuit must first exist. Connections to both ends
of the antenna are required to create a current. Again:

Again return to the earlier post:

But again we still have that essential requirement. Both an
incoming and outgoing circuit path must exist - else no
current flow.

Electrostatics:

Take two metal spheres, floating in space, isolated. Say one has no net
charge, it is neutral. Say the other had a huge amount of charge placed on
it.

Bring them together. A lot of charge flows from one sphere to the other.
Moving charge aka current. No return path. No complete circuit.

Take a heavily charged rod, touch it to an uncharged car. A lot of charge
flows to the car. Current. No return path. No complete circuit. Heavy
relevance to a question about a charge being applied to a car.

Capacitor:

A capacitor has no conductive path through it. There is no complete
circuit. Charge still flows.

Antenna:

Take a straight length of a single wire. Apply a voltage source to the
middle. Charges race up and down the antenna. Moving charges ... no return
path. In fact if there were charge returning on some return path, the
fields of the return charge and original charge would largely cancel, and an
antenna
wouldn't radiate much.

Top-posting:

Avoided by some, only as a matter of etiquette.


Please stop repeating elementary school science to me. This is an
electrical engineering newsgroup.

j
 
O

operator jay

Jan 1, 1970
0
Please stop repeating elementary school science to me. This is an
electrical engineering newsgroup.

That's rude. Let me withdraw that and say, you don't have to dumb it down
for me, if you want to discuss something I said, just give it to me straight
and concise.

j
 
W

w_tom

Jan 1, 1970
0
Apparent is a confusion between electrostatics and
electricity. This confusion should not exist on an EE
newsgroup discussion where EM fields is a required course.
Major difference between charged particles (or plasma) moving
through air verses the flow of electrons. Major difference
between an EM field verses electric current flow. Sometimes
both exist simultaneously. But two charged spheres exchanging
charged particles is not electricity. Electricity requires a
complete circuit for current to flow.

Even a capacitor demonstrates the principle. A complete
circuit is required; else no current flow through capacitor.
Therefore even the capacitor, like all current carrying
devices, has two ports. An incoming and an outgoing wire both
required so that current can pass through the capacitor.
Without both, then no current passes through the capacitor.
Quite simple concept. Without an incoming and outgoing path,
then no electricity flow - as taught even in elementary school
science.

Antenna does same thing. Antenna in a circuit only creates
current flow when the antenna connects to a complete circuit.
How large is that current? One must first provide numbers
such as frequency of EM field, size and orientation of
antenna, etc.

Same applies to the car. Without both an incoming and
outgoing path, then no current passes through electronics;
disrupts operation.
 
O

operator jay

Jan 1, 1970
0
You claim a capacitor has two ports. Obviously you mean, two leads (it is a
one-port device, as you know from your electrical engineering education). I
also am aware that they have two leads. I maintain that the leads end on
plates (or similar, effectively) inside the capacitor and that the plates
are separated by a dielectric. I therefore say there is no complete circuit
through a capacitor.

You have stated
"Electricity requires a complete circuit for current to flow."

1. Do you agree that a person can apply electricity to a capacitor, and see
current flowing?

2. If so, I would like for you to tell me where the complete circuit is in
a capacitor.

Please answer my questions 1 and 2. Just answer them briefly. #1 you could
answer with a yes or a no, I'm just asking whether you agree with the
statement.

Soon we can get back to the charge inflicted car.

j
 
W

w_tom

Jan 1, 1970
0
Maybe you could explain to other engineers that no current
flows through a capacitor. I am sure they would be quite
surprised. Capacitors have two wires for good reason -
electric current flow - an incoming and outgoing path. Other
two wire devices are resistors and inductors. Those too
conduct electricity only when both the incoming and outgoing
paths are in a circuit.

To me, the capacitor discussion is an irrelevant distraction
to the original posted question. If you have a problem with
the concept, then ask someone else. Meantime, if no current
flows through control circuits - and that means both incoming
and outgoing circuit path must exist - then the control
circuitry is not adversely affected. To have electricity flow
through and interfere with control circuitry, then first a
complete circuit - an incoming and outgoing path - must exist.
 
O

operator jay

Jan 1, 1970
0
w_tom said:
Maybe you could explain to other engineers that no current

I could explain it to you, if you ask. I don't know that I need to explain
it to any engineers. They probably know how it actually works, and, if they
like, they'll use a concept of displacement current in their capacitor-type
reckonings if there is any need and it is appropriate and suitable.
flows through a capacitor. I am sure they would be quite
surprised.

I'm not so sure as you are.

Capacitors have two wires for good reason -
electric current flow - an incoming and outgoing path. Other
two wire devices are resistors and inductors. Those too
conduct electricity only when both the incoming and outgoing
paths are in a circuit.

To me, the capacitor discussion is an irrelevant distraction
to the original posted question.

It was a relevant distraction, for the purpose of showing you your concepts
fail in certain cases. Since you were hanging onto them, and using them as
basis to counter stuff I put forth, it was unfortunately a necessary
distraction.

If you have a problem with
the concept, then ask someone else. Meantime, if no current
flows through control circuits - and that means both incoming
and outgoing circuit path must exist - then the control
circuitry is not adversely affected. To have electricity flow
through and interfere with control circuitry, then first a
complete circuit - an incoming and outgoing path - must exist.

There are ramifications of these assertions. They seem to be based on an
assumption that it is impossible for charge to accumulate anywhere in the
universe at any time, and seem to imply that capacitors do not work, nor
antennas, for starters.

I was going to show you that your concept "need a complete circuit for
current flow" fails in certain situations. It's an assumption we make when
appropriate, but set aside when not appropriate. You believe in it too
strongly, and, in fact, I see you have attempted to redefine 'electricity'
and 'current' and gone to other lengths to avoid having to consider that
possibility. You could have learned something here, and come out ahead OR
by presenting valid counter arguments to me you could have helped me to
learn while sharpening up your own processes. If I recall correctly, you
had strong opinions about lightning and its effects and side effects.Someone
was askng about a laptop, and, I believe, there was discussion of the type
of material a table was made of. I don't recall well, but I thought at the
time you had made some valid point(s). How do you figure all that charge
builds up in clouds, if there must be charge flowing back out, as soon as
any charge flows into a cloud region? We have to be careful when
rhuminating on the topic of eletrical goings-on, because our hidden and
implicit assumptions sometimes do not hold.

As an example, are you familiar with the problem of feeding motors with high
frequeny PWM speed drives, via longish conductor runs? All the usual
circuit analysis does not reveal any problem with the setup, yet too many
motors fail. When one looks at it from travelling and reflected waves
(whose root is the solution of time domain distributed parameter systems),
one can explain how a problem occurs. One can, in fact explain the noisy
jangly mess which can by recorded by oscilloscopes. But one doesn't get
these results by just applying Ohm and Kirchhoff, the normal duo, with the
normal methods.
 
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