Each new cell phone could have an on-chip circuit designed to run an occasional test to verify the electrical characteristics of the speaker and the vibrator motor. If one is out of spec, it activates both circuits. If the battery has been pulled or the phone turned off, the vibrator motor is briefly activated after power is restored. There could be a random delay.

The idea is to make a cell phone too unreliably dangerous to use as a detonator for a roadside bomb. Activating the vibrator briefly each time power is restored would trigger any mechanical connection to the vibrator. Again, after a random and unpredictable delay.

I believe the function could be designed into the appropriate chip at little extra cost; it's rather simple. Not that it couldn't be beaten, but it would make life a bit harder for the bomb makers. Maybe even shorten a few of their lives.

1. Thank you for the welcome. 2. Cell phones ARE being used for roadside bombs, which is why our troops use phone jammers. 3. The resistance wire of detonators, added to any circuit that can supply enough power, can easily be detected. Look at what most cell phones do now--adding this automatic test is not complicated. 4. Checking the electrical characteristics of power circuits at turn-on or battery plug in can be done with an infinitesimal amount of power. Battery life would be unaffected. 5. This does not, in any way, make the phone unreliable. 6. Yes, it can be defeated. But these people aren't rocket scientists and you aren't looking ahead. What's to say this type of trigger will stay in the mideast? When can you expect to see the first one used in a western country? The easiest way to make a cell phone into a detonator is to swap a model rocket igniter for the vibrator motor or the audio transducer, and that's the sort of thing I was thinking of detecting. Feel free to expand on the possible capabilities. I'm not seeing too much creativity here. Is that typical of this site? 7. No downloadable app would prevent the check as it would be on the chip, not in a program. 8. The more complicated a detonator has to be, the more likely it is to fail.
-- Zimminger, Sep 01 2009

I like this. Maybe light up the display from time to time too. Of course, this would put a premium on older more "reliable" phones, but [+] for trying.
-- coprocephalous, Sep 01 2009


It isn't necessary to modify a phone at all to use it to initiate an IED. But, like [copro] said, [+] for trying.

Oh, and welcome to the HalfBakery.
-- 8th of 7, Sep 01 2009


'Make technology unreliable so it is harder to (ab)use it?' Fun idea. Clocks could go into fast-forward if they fail a self-test, and cars could activate the air-bags if driven overly fast on rough roads while being suspiciously overloaded. Also: civilian night-vision equipment will blind you via IR laser if the scope picks up a uniformed soldier. With planes the tech is even trickier: It would have to subtly interrogate possible hi-jackers as to their most cherished place on earth, then fly there and crash in it. Or something. [-]
-- loonquawl, Sep 01 2009


I think the idea is slightly overcomplicated as far as an "easy" solution goes, and essentially unworkable as far as a more advanced solution.

The simplest approach to using a cell phone to trigger an external device is to wire the speaker and/or vibrator so that any attempt to produce noise or shake will trigger the device. A simple way to discourage the phone from being used in this fashion would be to make it, at random occasions, output a slow ramp wave to the speaker and a brief pulse to the vibrator. Such things could be done in such a way as to be unnoticeable, but so as to fire simplistically-wired trigger devices.

Unfortunately, the only effect this would have would be to force people using phones as triggers to slightly increase the sophistication of their trigger electronics. Unless the phone actually rang at random intervals, it would be easy for some electronics to filter out the spurious glitches. Nice thought, but I think other approaches in cooperation with the phone company may be better.
-- supercat, Sep 01 2009


I do not believe it is difficult for a terrorist to buy basic electrical components or scavenge them from old appliciances and make a bomb detonator with them. Terrorist networks like Al Qaeda have plenty of technical expertise and for practical purposes can make a bomb out of anything. The way to combat them is to send soldiers after their bases and find their cells with our security agencies. Which is what we have (albeit ineptly) been doing.
-- Bad Jim, Sep 01 2009



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