"Touch those tanks and ... Kaplooey"
the mad max interceptor booby trap
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Last updated Jan 5. 2020.
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Legit or Film Prop?
For various plot reasons, directors demand that
some movie "bombs" need to be overcomplicated
Rube Goldberg devices mixing colourful liquid gel
binary explosives, while others have to "look" like
a proper bomb because
everyone knows that
bombs require coiled red and blue wires, a
massive LED display counting down to zero, and
invariably
always make beeping noises.

Unfortunately, real IEDs tend
not to be overly
photogenic.

I paid little attention to the booby trap beneath
Max's interceptor when I first saw the film in 1982,
and although I've probably seen the film an
honest four score times since, the device always
tended to lose me at the prominent ignition coil.

Always having presumed that props had simply
tacked a bunch of junk to the bottom of an old
cake tin and called "looks good enough".

As a freak of nature as well as a hard core Max
fanboy, I've always wanted my own Max booby
trap - but could never quite bring myself to just
mount a stupid prop with a switch, and so I've truly
hated this damnable thing for over 38 years.

However. After reviewing the film yet again - either
due to paying a bit more attention, or just a
certain cock o' the eye - I noticed that one of the
other prominent devices affixed to the box was an
old school mechanical voltage regulator missing
it's cover.

Wait a minute...
Now truthfully, although I barely recall how they
operated (Although I once knew how to adjust
them, I haven't personally seen one in many
decades), I do recall that they utilized two or three
solenoid coils to make and break contact.

Where there are coconuts, telephone is possible.
All of the bits are there; almost certainly one of
these old regulators could be reconfigured as an
astable multivibrator switching battery current -
and therefore capable of driving an ignition coil,
producing high voltage.

What sealed the deal for me though, were the
electrodes.

We know from the film that max utilized a black
powder fuse to detonate the actual charge, and
an electric arc will certainly ignite cannon fuse.

So .. High current oscillator, ignition coil,
electrodes, fuse...

Holy shit - this is in fact the real McCoy - or at
least a version which would have been relatively
easy for Max, who we know was an apt
motorhead, to fashion from scavenged items.

Exposing the regulator innards beneath the
vehicle almost certainly George Miller's call - but
it's possible that in the Max fantasy universe that
the cover may have simply been lost in the
outback - or was never present when Max
fashioned the device.

Having finally found love for this device - clearly it
now must be built.

I'm not overly worried about making "the list". Not
only am I undoubtedly already a member, but the
device itself is really nothing more than a
relatively complicated electric match that'll give
you a rattle if you're careless with the high
voltage. Not an actual
bomb per se.
A typical now obsolete "vibrating points"
automotive voltage regulator with cover
removed.
Looking closely, I realized that with the parts visible, this
device could certainly have been functional.

Is it elegant? Well, there are far more reliable and
robust methods of igniting cannon fuse with electricity,
and the actual layout is somewhat sketch - but I
suppose in the post apocalyptic wasteland, Max had to
use what he could find.

I can't decide on whether to recreate an accurate copy
of the detonator exactly as seen in the film, ie - leave the
coil secondary with it's boot missing, the superfluous
rivets (we know that the mechanic took mere seconds to
remove the device after the interceptor  was towed into
the compound - and so they are unlikely the actual
mounting fasteners), the hand hammered chassis, etc - .
Or lend a bit of personal artistic licence.
The electrodes look suspiciously similar to those one
might find in an oil furnace ignitor.

Coincidentally, I recall noticing a furnace burner in the
back forty dump here on the homestead - along with
various bits of an early 70's Ford pickup. These voltage
regulators (ubiquitous as well on old tractors) were often
replaced in the day. What might the likelihood  of finding
one abandoned there as well? I'll find out later today.

There would be a certain special authenticity this build if
in fact we could fashion our unit entirely with bona fide
scavenged bits.