A group of us were discussing the effect of a blackout bomb on the infrastructure of the United States, our company and our personal possessions. One of our group claimed that his 1970 Ford pick-up would be ok since if it received a dose during an EMP attack, all he would have to change is the coil. While we agreed that modern cars with the integrated electronics would be toast, is this true what he would simply need to change the engine coil if he car was effected? Does anyone know what other parts of an older car, such as the alternator, would need to be changed? Sicne he loves his truck so much and was rather smug about it, I’m very interested in if he was correct or not.
I don’t know much about fords, but I have a kit car which is essentially a modified 1960 vw bug. The electrical system on that thing is so simple that I can just about draw the whole thing from memory without much effort. The coil and alternator are the only two essential parts with fairly small wires that I can think of. There’s a temperature sensor that will stop fuel from flowing if it fries, so maybe that would go too.
Bugs are known for their simplicity, but I can’t imagine a 70’s truck having too much more complicated stuff on it, at least not critical stuff.
While it is true that the old coil/condenser/points system is very robust ( I doubt your friend would have to even replace the coil) solid state equipment can be shielded against EMI and is routinely done in military equipment.
Thanks for the two answers. I am going to bump this since I am figuring somewhere among the collective brainpower, a person has an answer. Come on Q.E.D., show me the light.
I wish I could, but my answer would be nearly identical to engineer_comp_geek. The only vulnerable element in a car that old is the ignition coil, that I can think of. There might have been some rudimentary control electronics, but none that would have been critical.
I doubt there’s “an answer”. There are a range of answers. EMP works by inducing a current in a conductor. All else equal, a coiled conductor is more sensitive than a straight conductor.
An air-burst nuclear weapon, or one of the DoD’s new experimental EMP weapons, will create a very brief, very strong E-field across a wide frequency spectrum. Like any other field phenomenon, the inensity drops off as the squure of the distance from the source.
Let’s use a hypothetical non-nuclear EMP weapon, sorta like the DoD hopes to perfect soon.
One Possible Scenario Of Results:
2 miles away from detonation: no effect on any electronics
1 mile away: cellphones fried, cars unaffected
1/2 mile: computer-controlled cars fried, digitial watches fried, old-style cars OK.
1/4 mile: old-style cars’ ignition coils fried, but only on 1/2 the cars, others unaffected. Ditto radios.
1/8 mile: all old style car’s igniton coils & radios fried, some voltage regulators fried
1/16 mile: all voltage regulators fried, some starter motors, alternators and heater fans fried
1/32 mile: most starter motors, alternators and heater fans fried.
1/64 mile: Car hit by shrapnel from explosion which drove EMP
1/128 mile. Car damaged by shrapnel from explosion which drove EMP.
etc.
Your question amounts to asking: a giant bolder is dropped in a park pond; how many ducks are tipped over by the waves? Answer: it depends.
Sound good and thanks for the answers. I suppose he is correct. If the United States gets hit by a blackout bomb I guess I will be calling him for a ride…well, yelling since the phones won’t work.
Then again, it seems that the coil sitting on your garage shelf is going to be toasted just as much as the one in your truck. So, when you switch it, it aint gonna work anyway.
Or neither of them will blow. In either case, switching in a new one won’t change the state of your engine.
Why would it? An unconnected coil is an open circuit. Although a voltage will still be induced across the coil, there will be no current flow, unless the induced voltage is sufficient to cause arcing across the airgap between the terminals or to cause corona breakdown of the insulation between windings. No current, no damage.
Depending on what the open coil is up against, it may not be an open circuit. Air can conduct electricity and can complete the circuit if the voltage is high enough. Spark plugs and lightning bolts are examples of this.