The simple circuit
of Fig.1 emulates a similar conjuring trick which sells for hundreds of Pounds.
The trick seems to do the almost-impossible from an electronic point of view,
let alone from the point of view of common sense.
It consists of a bank
of three on-off switches (S19-S21), which have three switch covers, each of a
different colour. These switch a bank of three lightbulbs (LP1-LP3), each of a
different colour. The colours of the lightbulbs correspond with the colours of
the switch covers.
Now comes the interesting part. The switch covers may
be exchanged at will, but still they switch the lightbulbs of corresponding
colour. Similarly, the lightbulbs may be exchanged at will, but still they
respond to the switches of corresponding colour. On the surface of it, there
would seem to be 64 possible connections between switches and lighbulbs, and no
possible way that the conjurer can manipulate them all.
However, add some
sleight-of-hand, and things become a lot simpler. Each switch cover is
symmetrical, in such a way that it looks the same whether facing N, E, or W.
Further, each lightbulb is screwed into a circular base, which looks the same
whether facing N, E, or W.
Let us consider just one of the switch covers
(S19). Three reed switches (S10-S12) are positioned beneath the cover, at
positions N, E, and W, and each of these activates a different lightbulb. Any
one of the three reed switches may be closed by a single magnet positioned
strategically under the switch cover. Depending on the orientation of the switch
cover, therefore, the switch will activate any one of the three reed switches,
and thus the selected lightbulb.
On discussing this with an accomplished
magician, the author was told that this alone would be sufficient for the full
effect described - reed switches S1-S9 may be omitted. Nevertheless, the
lightbulbs may similarly be surrounded with three reed switches each, which are
activated by the orientation of the circular base - a magnet being strategically
positioned within it. These reed switches may thus reroute the power to the
conjurer's selected lightbulb.
There is just one caveat from an
electronic point of view. Carefully consider the voltage and power ratings of
the reed switches and on-off switches, to match these with the chosen
lightbulbs. Failing this, your trick may demonstrate how none of the switches
will activate none of the lightbulbs.