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This electric firing
system's main feature is that it is expandable. Why would you want to
have an expandable firing system? The main reasons are time and
money. After you make a electronic firing system, you will usually
outgrow its capabilities after awhile. Instead of starting over from
scratch, it is much more time and cost effective to have a firing
system that can expanded. Also an expandable firing system can be
expanded as you get the money and time to add on to it.
Document
and pictures © copyright 2003-2004 by Joe Zastrow.
FEATURES
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Expandable
It can have one slat with 15 or 20 cues or up to six slats for a
total of 90 or 120 cues.
Simultaneous firing of cues
It is designed to optimally fire up to 3 cues at once, but might
handle up to 6 at once.
Uses Slats
It uses slats to save set up time and reduce costs.
Separate cables for negative and positive slat wires
This reduces chance of shorts or wire heat up.
Cheap igniters
It uses cheap thin high resistance wire instead of expensive
e-matches.
Power Connectors
It has power connectors on the slat cables and the firing panel to
make the connecting and disconnecting of the slats from the firing
panel much faster.
Rotary switches for
cue selection
This reduces the chance of firing the wrong cues and reduces the
number of switches needed.
Push buttons for cue
firing
Momentary push buttons are easier to use during a show.
Separate toggle
switches and power lights for slats
This allows slats to be turned on, off or tested in groups or singly.
It increases safety and reduces the chance of testing the wrong cues.
No soldering
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This firing system
consists of several parts that must be constructed. This diagram
above shows how all the parts work together to ignite a fireworks of
a show.
First of all, the
firework with its fuse needs to be ignited. An "igniter" is
attached to the fuse. When electric power is applied to the igniter,
it heats up very fast and very hot (up to 2500F) and that heat
ignites the fuse of the firework.
Two wires are attached
to the igniter. These wires supply the positive (red) and negative
(black) power to the igniter. These two wires as a unit are called a
"shooting wire".
The other end of the
shoot wire is connected to two metal terminals on a box. The two
terminals are called a "cue" and they supply power to the
shooting wire. The box is called a "slat". The slat usually
has a number of cues on it (in the diagram, 20). Other shooting wires
are attached to those cues. Those shooting wires will go out to other
igniters on other fireworks. The slat acts as a hub or a central
distribution point of power for all the fireworks around it. If there
is more than one slat, the slats are placed close to groups of
fireworks or distributed evenly over the firing zone. This minimizes
the distance a firework is from a cue which minimizes the length of
the shooting wires. Shorter shooting wires means less wire that has
to be bought, stored, transported and setup. This saves time
and money. In the diagram, there are six slats, two on the left side,
two in the center and two on right side of the firing zone.
Shooting wires are attached to cues on these slats as well. If there
were three slats, there would be a left slats, a center slat and a
right slat.
The cues on a slat form
a grid of rows and columns. Each cue can be uniquely identified by
the row it is in (Left slats=A-D, Center Slats=E-H, Right Slats=I-L)
and the column it is in (0-4 or 5-9). In the diagram, a shooting wire
is attached to the cue in row A, column 2 or cue A2. There are also
shooting wires attached to cues A7, A9, E2, E4, E7, I2, I4 and I7.
Examine the cue A2. The
positive wire is attached to the lower terminal in the cue, while the
negative is attached to the upper terminal. Lower terminals in a cue
are positive and the upper ones are negative. All the positive
terminals in one row are connected to each other while all the
negative terminals in a column are connected. So there is one
positive wire for each row on a slat (total of 4) and one negative
wire for each column of a slat (total of 5). So cue A2, uses row A
wire for positive power and column 2 wire for negative power. Cue E4
would use row E wire and column 4 wire.
Together the nine wires
(4 rows and 5 columns) are called a "slat cable" because
they go from the slat to the firing panel. The positive wires are in
a four wire cable and it is called the row cable (red) or row wires.
The negative wires are in a five wire cable (black) and it is called
the column cable or column wires. They are in separate cables to
reduce the chance of shorting and heat build up. The slat cables can
range in length from 30 to over 100 feet.
Using slats and slat
cables enormously reduces the amount of wire needed in an electric
firing system. Wire is one of the most expensive parts of a firing
system. Instead of running 20 shooting wires (40 individual wires)
from the fireworks to the firing panel, only 9 wires run the long
distance between the slat and firing panel. Then twenty much shorter
shooting wires connect the cues to the fireworks.
There are power
connectors on the end of the slat cables and on the firing panel. The
slat cables can be quickly plugged into and unplugged from the firing
panel. This speeds up set up and tear down time because it is much
faster to plug/unplug six cables instead connecting/disconnecting 54
wires. Also storage and transportation of the firing panel and the
slats is easier if they can be disconnected from each other.
The "firing
panel" is where you decide which cue (or cues) will be
"fired" (have its power turned on) or tested. Each of the
three toggle switches and power lamps control one or two slats. The
toggle switches turn on, turn off or put into test mode the slats
they control. This saves time during show set up and testing. The
cues can be tested in the same order that they are fired for the
show. They also act as emergency shut offs.
A rotary switch is used
to choose the row of a cue. A momentary push button is used to choose
the column of a cue. The cue is fired when the button is pushed. In
the diagram, the left rotary switch is set to row A. Pushing
the 2 button will fire cue A2 on the left slat. If the center and
right slats are turned on, pushing the 2 button will also fire cue E2
on the center slat and cue I2 on the right slat because the rotary
switches for those slats are set to row E and row I. So three
fireworks will be ignited at once from different areas of the fire
zone. Since each rotary switch controls two slats, pushing the 7
button will fire the cues A7, E7 and I7.
Using rotary switches
for the rows and buttons for the columns, instead of one switch for
each cue, reduces the number of switches needed. This reduces costs
as switches are another expensive part of a firing panel.
Rotary switches also reduce the chance of firing the wrong cues. If
you switch from row A to row B, row A is automatically turned off
when row B is turned on. With individual row switches, you might
forget to turn off row A.
The power for the
firing panel is supplied by a 12 volt battery which is connected to
the firing panel with a positive and negative wire.
Now the parts of the
fire system have been described, we will see how each of these parts
are constructed.
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CONSTRUCTING
THE IGNITER
Materials (for each igniter)
- 3-4 inches of 30-38
gage high resistance (nichrome) wire.
- Black electrical tape (Scotch vinyl plastic electrical tape)
- A fuse attached to one or more fireworks.
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The igniter is the
simplest part of the firing system. It is attached to the fuse
of a firework, beforehand and off site from the show, when you
are preparing your fireworks and set pieces for the show. The
igniter uses about 3-4 inches of thin high resistance wire. High
resistance wire is the same wire that is used in the heating
coils of toasters and electric heaters. The wire is wrapped
around the fuse in a small coil. Make sure it does not
touch itself as this will cause a short and it will probably not
ignite the fuse. Do not wrap all the wire around the fuse, but
leave about 0.5-1 inch on each end. The diagram to the right
shows this in more detail. To prevent the igniter from slipping
off the fuse, wrap some electrical tape between the wire and the
end of the fuse. Sometimes this piece of tape will fly off
harmlessly with a "poof", much to the surprise of the
audience. To prevent sparks from other fireworks from
prematurely igniting the fuse, wrap more tape around the rest of
the fuse.
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Igniters usually can
not be reused. You have to have a new one for every fuse you want to
ignite You could also use purchased or home-make electric matches
(e-matches) as igniters. Click
here to see how to make your own e-matches. E-matches are
more expensive to purchase (about $1 a piece) or more time consuming
to make than just using high resistance wire, but they ignite quicker
and require less power. High resistance wire can be purchased for
about $35-40 pound. A pound is about 4,500 feet of wire. That would
be enough for about 13,500 to 18,000 igniters or less that a four for
a penny.
You can purchase high
resistance wire at www.resistancewire.com,
www.firefox-fx.com,
www.skylighter.com
or other places that pyro supplies are sold.
I use 31 gage nichrome
(EvanOhm) 3-4 inch wire. In my tests, three cues can be
simultaneously ignited with about a 1 second delay. Six simultaneous
cues have about a 4-6 second delay. This is probably the limit as the
wires are not as hot and they all have different temperatures. You
may have to experiment to find the "ideal" length for your
igniter if you use wire with a different thickness or resistance.
Thinner wire may have to be longer so it doesn't break or burn up too
fast. Thicker wire may have to be shorter so it does take as too long
to heat up. Higher resistant wire may have to be shorter while lower
resistant wire may have to be longer.
Click here to see
the page on different types of resistance
wire.
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CONSTRUCTING THE
SHOOTING WIRE
Materials
(for each shooting wire)
- 4 alligator clips, 2
inch or 50 mm long (Gardner Bender, 14-076)
- 18-22 gage 2 wire cable (length 5-16 feet?)
For every cue fired in
a show, there needs to be one shooting wire. It is also a good
idea to have a few extra ones. Shooting wires can be expensive.
Alligator clips can cost $0.22-0.40 a piece. Two wire cables can be
$0.06-0.10 a foot or more. One shooting wire can cost $1.25-$3.00 or
more. Try to buy the wires and clips in bulk. It is cheaper to buy a
500- foot roll of cable than smaller lengths. Solid core wire works
better and is usually cheaper than stranded wire, but both will work.
Higher gage wire is usually cheaper than lower gage wire. I usually
use 18 gage, 2 wire (18/2) thermostat (or security alarm) wire
because it is more durable and has a second layer of insulation
around the two wires. Do not confuse it with lawn sprinkler wire
which is more expensive as it is rated for below ground usage.
Thermostat wire can be purchased locally from most home improvement
stores (Home Depot, Fleet Farm, Lowes, Menards, etc.).
Two-wire bell wire will also work.
The length of the
shooting wire will depend on your show and how far away the fireworks
are from the cues. I usually make two lengths (8.5 and 16 feet). If
needed, two shooting wires can be clipped together to make one longer
wire, though you have to make sure the clips from the positive and
negative side don't touch or you igniter will fail.
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To make the
shooting wire, cut a length of two wire cable. Strip 1/2 inch
insulation from the four ends of wire. Attach an alligator clip
to each of the four ends. To attach an alligator clip, feed the
end of a wire into the barrel of an alligator clip. Push it
through until the end reaches the screw terminal. Then wrap the
wire clockwise around the screw and tighten it. Don't crimp the
barrel. If an alligator clip gets burnt or destroyed (as some
always do during a show), it will be easier to remove the clip
and replace it. Below is a picture of a shooting wire with its
four alligator clips.
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During show setup,
the shooting wire clips are attached to the igniter wires. The
clips must not touch each other. The shooting wire may also have
to be taped to the firework or the board that the firework is on
so that the wire and clips do not pull too hard on the fuse and
the igniter. The shooting wires and clips should not be where
the pyrotechnics emit from the firework. Otherwise, the wire and
clips will get burned and they will also interfere with the
performance of the firework. This can also be dangerous.
Sometimes, fountains have very short fuses. In that case, use
black electrical tape and a short piece of fuse to lengthen the
fuse. Extend the fuse over the side of the fountain and tape it
down. Then attach igniter near the end of the extended fuse.
The clips can then be attached and be out of harms way.
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Another way to
prevent a fuse from being prematurely ignited by sparks of other
nearby fireworks is to turn the fuse away from the nearby
fireworks that are fired earlier in the show. Then firework
itself acts like a wall which shields the fuse from sparks.
Click on the
thumbnail on the right to bring up a full-sized version of the
alligator clip/igniter setup for a firework. |
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CONSTRUCTING THE
SLAT
Materials
(for each slat)
- one 12" long x
10" wide x 1/2" thick board (top cover)
- two 12" long x 3" wide x 1/2" thick boards (back
& front boards)
- two 9" long x 3" wide x 1/2" thick boards (left
& right boards)
Note: As long as the above boards are the same thickness,
1/2"-3/4" thick boards can be used, but then the left and
right boards would have a length of (10"
minus (2 times the board thickness)).
- 14 1.5 inch wood
screws
- 40 #8-32 x 1.5" zinc Truss head machine screws
- 40 #8-32 zinc machine screw nuts (coarse thread)
- 80 #8 zinc washers
- 20 3 amp, 50 volt or more diodes (1N5400-1N5408)
- 20 Twist-on wire connectors (blue, must handle four, 18 gage
wires), (Gardner Bender, 10-002).
- one 9- conductor male molded nylon (power) connector (Radio Shack,
274-229)
- 5 feet of 18 gage red
hook up (bell) wire (Radio Shack 278-1217)
- 4 feet of 18 gage black hook up (bell) wire (Radio Shack 278-1217)
- ?? feet of 18-22 gage, 5 wire cable (enough cable for the row and
column cables of the slat cable)
- Duct tape
- Latex Enamel Paint, Porch and Deck Paint, or Fire Resistant Paint.
The wood of the slats
are exposed to sparks from the fireworks. To make them last longer I
use wood with a Formica surface. Formica is the "plastic"
covering that is found on kitchen counter tops. It can resist
temperatures over 300°F. After every show my slats look terrible
from soot and burn marks. I usually only have to rub them with a
soapy rag and they become clean again, because of the Formica
surface.
I go to a salvage yard
and purchase an inexpensive used counter top to use for the slats. It
then gets cut to the dimensions mentioned above. Counter tops are
usually about 3/4" thick. Formica covering and glue can be
purchased from most home improvement stores. This covering is cut to
the same size as the board and glued to it. This is done before the
holes are drilled. Some home improvement stores sell shelf boards
that have a white plastic "Formica-like" covering. It
resists sparks also, but not quite as well as Formica. The shelf
boards come in pre-cut 10" wide pieces, which is perfect size
for the slat top cover.
For the row and column
cables of the slat cable, I use 18 gage, 5 wire(18/5) thermostat
wire. The fifth wire of the row cable is not used. It is possible to
find 4 wire thermostat wire, but I found it is usually cheaper to buy
twice as much 18/5 cable than buying a 18/5 and a 18/4 cable. Any
wire with 18-22 gage could be used, but 18 gage wire has less
resistance which means there is more power for heating the igniter.
The thermostat wire is color coded, so it is easier to wire the slats
and firing panel. Also each of the cables is wrapped in another
layer of plastic insulation for more protection.
The length of the slat
cables depends on what sort of show you are giving and what is your
"safety distance". There has to be enough cable to go from
the firing panel to the slats and still have the firing panel
operator a safe distance away. I have used 30-35 feet for safe and
sane fireworks (ground fireworks like fountains, wheels, strobes and
ground spinners). In a Black Cat Fireworks catalog, it
recommends 50 feet for fountains, 60 feet for roman candles and 80
feet for everything else.
But more wire adds more
resistance as do more simultaneous cues. For example, if the total
length of wire to the firework (cable plus shooting wire) is 50 feet
or less, 3 simultaneous cues will light in about one second, while 6
simultaneous cues will light in 4-6 seconds. If the wire reaches 100
feet, 3 simultaneous cues will light in about 3 seconds. If the wire
reaches 200 feet, only one cue can be lit in about 3 seconds.
This assumes a 12 volt, 7 amp battery.
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All the slat
cables can be the same length, which makes them very
interchangeable. But the cables for the left and right slats
could be longer than the center slat. This diagram shows how to
use the Pythagorean Theorem to calculate an estimate for cable
length for the left and right slats. It assumes you know the
length of cable for the center slat and the distance of the left
and right slats from the center slat. For example, if the length
of the center slat cable 'A' was 40 feet and the left
slat was 30 feet from the center slat, then:
Cable 'C' =
SqrRt[ (40x40) + (30x30) ]
Cable 'C' =
SqrRt[ (1600) + (900) ]
Cable 'C' =
SqrRt[ 2500 ]
Length of Cable 'C'
= 50 feet
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Constructing the Slat Box
First, the outside
box of the slat must be made. It will have dimensions of
12" long x 10" wide and about 3.5" high. In the
very center of the front board drill one 3/8" hole (H1). It
should be 6" from either side and 1.5" from the edges.
This is where the slat cable will come out of the box.
At the corners of
the box, drill one (or possibly two) 1/8" starter hole
through the ends of the back and front boards into the left and
right boards. Then screw in the 1.5" wood screws.
Note: All of
the slat diagrams in this section can be enlarged to produced a
scaled version (0.01" per pixel, 12"x10"),
which can be printed off to get a actual size diagram.
Printing at 6"x5" will give a
half scale diagram.
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Constructing
the Slat Top Cover
Next the top cover
of the box must be constructed. Place the top cover squarely on
the top of the slat box. Drill six 1/8" starter holes
(S1-S6) through the top cover and into the sides of the box.
Screw in 1.5" wood screws. S1, and S5 are 3"
from the left edge. S2 and S4 are 3" from the right edge.
S3 and S6 are 5" from the back edge. All
holes are 1/4" from their closest edge.
Click the
diagram on the left to enlarge the view.
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Any surface of the slat
that does not have Formica on it should now be painted. The inside of
the slat does not need to be painted but any unfinished top, sides or
edges that sit on the ground should be.
Use a permanent marker
and ruler to make grid lines on the slat cover. The vertical
grid lines are 1, 3, 5, 7, 9 and 11 inches from the left edge and
parallel to the left edge. The horizontal grid lines are 1, 3, 5, 7
and 9 inches from the back edge and parallel to the back edge. At
some point, the left and/or right edges should be labeled with the
appropriate row letters (Left Slat=A-D, Center Slat=E-H, Right
Slat=I-L). The front and/or back edges should be labeled with the
appropriate column numbers (First set of three=0-4, Second set of
three=5-9).
Drill 5/32" holes
for the terminal cues. Drill the first column cue (C0) starting at
1.5" from the left edge and 1.5" from the back edge. Drill
three more holes exactly 2" apart below this first C0 hole
(3.5", 5.5", and 7.5" from back edge). Move 2" to
the right of the first C0 hole, to drill the first C1 hole at
3.5" from the left edge and 1.5" from the back edge. Drill
the rest of the C1 holes 2" to the right of the C0 holes. Do
this for C2, C3 and C4 holes, each column of holes is 2" to the
right of the previous column.
Drill the first R1 hole
at 2.5" from the left edge and 2.5" from the back edge.
Drill four more holes exactly 2" apart to the right of this
first R1 hole (4.5", 6.5", 8.5" and 10.5"). Drill
the rest of row holes always 2" below the previous row holes.
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Wiring the Slat
Flip the box over
from left to right, so the bottom of the box is in view.
Look at the diagram on the right (click on it to bring up a
larger version). Warning: since this view is of the
bottom of the box, all the holes are reversed from left to
right, but hole H1 will still be in front. Into each terminal
hole, stick a machine screw with two washers (one inside and one
outside the box) and the nut on the outside of the box (see
below). Tighten the nut, but it should still be loose. |
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It is time to wire
the rows of the cues. Take about a 15" piece of red 18 gage
wire. Strip one end and wrap it around the first terminal
(machine screw) in R1. Tighten the nut. Stretch the wire to the
next terminal in R1. Cut the insulation where it meets the
terminal, but do not cut the wire. Slide enough insulation down
the wire to expose enough bare metal to wrap it around this
terminal and tighten the nut. Continue this process for all
terminals in R1. At the last terminal in the row, cut off any
extra wire. Do this same process for each row on the slat
(R2-R4).
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This diagram on
the left shows how to wire the columns of cues (click on it to
enlarge). Start at the first terminal in C0. Attach a diode to
the terminal and tighten the terminal. Attach a twist connector
to the other end of the diode. IMPORTANT: The end
of the diode WITHOUT the black band (anode) is attached to the
terminal. The end WITH the black band (cathode) is attached to a
twist connector. It MUST be this way for every diode.
Next take a 3" piece of 18 gage wire and strip 3/8" of
insulation from each end. Stick one end into the twist connector
and twist tight. Stick a twist connector on the other end of the
wire. Move down to the next terminal in the column. Attach the
diode to the terminal and the twist connector. Add a wire to the
twist connector to go down to the next terminal in the column
and add a twist connector to the other end of the wire. Continue
this for all four terminals in column C0 as shown the diagram.
Repeat the whole process for each column of the slat.
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Discussion and
Testing Cues
At this point, you may
be wondering what does a diode do. A diode forms a one way electric
wire. Electricity can flow from the terminal, through the diode and
to the twist connector. It can not flow the opposite direction. It is
similar to a one way street. The black band indicates which way the
electricity can flow. For more information about diodes visit: www.americanmicrosemi.com/tutorials/diode.htm
Diodes are needed on a
slat to prevent the ignition of the wrong cues. This is caused by
power flowing backwards through the wires. Let us see how this works.
Assume the cue (R1,C4) is fired. Power flows from the battery along
the red R1 to the terminal that the R1 arrow points to. There
is an igniter from this terminal to the terminal that the C4 arrow
points to. The power flows from that terminal, through the diode and
out the black C4 wire which will eventually go back to the battery.
The circuit is closed, the igniter heats up, just as it is suppose
to. Now assume there are also igniters at cues (R1,C3), (R2,C4) and
(R2,C3) and other cues on the slat. As the igniter at cue (R1,C4)
fires, it will frequently break and the circuit is then open. Power
is still flowing through the system because the panel operator has
not yet released the push button on the firing panel. Power now flows
along red wire R1. At cue (R1,C3) it goes through the igniter, the
terminal and the diode and along the black C3 wire. Since the C3 wire
is open, the power can't get to the battery. The power then attempts
to go through the diode at cue (R2,C3), but the diode stops it. If
the diode was not there, the power would flow backwards through
terminal and igniter over to the red R2 wire. Then it would flow
through the igniter at (R2,C4) and back over to the black C4 wire.
The power then flows back to the battery completing the circuit.
So after the igniter at cue (R1,C4) breaks, cues (R1,C3), (R2,C3) and
(R2,C4) all fire. Other cues will probably fire too. In fact, it is
possible that all cues on the slat might be fired. Also, if there are
no diodes, it will be impossible to test the cues. If you test cue
(R1,C4) and its igniter is broken, the test light will still light
because the test power can flow through cues (R1,C3), (R2,C3) and
(R2,C4) or numerous other paths to complete the test circuit. Diodes
prevent this from happening.
Use a ohm meter or
multi-tester to check the slat circuitry. Touch the first lead of
tester to the first terminal in R1. Touch the second lead to the 2nd
terminal in R1 and then all the terminals in R1. There should be
continuity at each terminal. Do this for R2, R3 and R4.
Next touch the first
lead to the first terminal in C0. Touch the second lead to diode wire
that goes into the last twist connector in C0. Touch each terminal of
C0 with the first lead. Depending on which lead is positive and which
is negative all the terminals will have continuity or none of them
will. Reverse the leads and test all the terminals in C0 again. The
continuity of all the terminals should be the opposite of what they
were from the previous test. Do this double test for all columns.
Adding Slat Cables
Measure and cut an
equal length row cable and column cable for the slat cable. Mark both
ends of row cable so it is different from the column cable. Line up
the one end of the two cables and stretch the cables out tight about
2-3 feet. Wrap some duct tape tightly around the two cables.
Wrap some duct tape about every 2-3 feet along the cables, so the row
and column cables become a combined slat cable. Strip away about
6" of the protective plastic layer from one end of the row and
column cables to expose the row and column wires.
Throughout the rest of
this document and in the diagrams, the colored wires in the cables
will be have the following meanings.
Row Cable
Red = Row 1 wire (R1)
White (shown in diagrams as black) = Row 2 wire
(R2)
Green = Row 3 wire
(R3)
Yellow
= Row 4 wire (R4)
Blue = Not used.
Column Cable
Red
= Column 0 wire (C0)
White (shown in the diagrams as black) = Column 1
wire (C1)
Green
= Column 2 wire (C2)
Yellow
= Column 3 wire (C3)
Blue
= Column 4 wire (C4)
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Now the rows of
the slat will be wired. Snip the blue wire in the row cable
short, so it is out of the way. Strip about 1/2" of
insulation off each wire in the row cable. Push the row cable
through the hole H1 in the slat. Attach red wire to the middle
terminal of R1. Attach the white wire to the middle terminal of
R2. Attach the green wire to the middle terminal of R3. Finally,
attach the yellow wire to the middle terminal of R4.
Now the columns of
the slat will be wired. Strip about 3/8" of insulation from
each of the wires in the column cable. Push the column cable
through H1 hole. Take the red wire (C0) and twist it into the
last connector in C0 column. Take each column wire (C1-C4) and
twist it into the last connector of its matching column. Click
on the image to enlarge.
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Now take a 1"
wide strip of duct tape and wrap it around the slat cable just
outside H1. This should form a plug that is bigger than H1. Do
the same thing inside H1. These plugs will prevent any pulls or
pushes on the slat cable from disturbing the wiring and
connections inside the slat. This picture is a bottom view
of a 3 row by 5 column slat.
Click on the
image to enlarge. |
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Adding a Connector
to a Slat Cable
Strip about 1.5"
of plastic insulation from both row and column cables. Snip the
blue wire in the row cable short. Strip 0.5" of insulation from
the other wires.
A continuity test could
be done, like was done earlier on the slat. Touch the end of the R1
wire with the first lead of the tester and touch any R1terminal on
the slat with the second lead. There should be continuity. Do this
for each of the rows. Touch the C0 wire with first lead of the tester
and any C0 terminal on the slat with the second lead. Reverse the
leads and do it again. There should be continuity on one test and no
continuity on the other test. Do this for each column. These tests
will also check if the slat wires were wired to the correct rows and
columns.
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This is a diagram
of one of the pins for a connector. Notice carefully how the
wire is placed into the pin. Tabs A will be wrapped and crimped
around the insulation of the wire. Tabs B and C will be wrapped
and crimped around the bare wire. The end of the wire must not
go past the point where the flanges of the pin (D) are attached
to the pin. Starting at the A tabs, use a needle nose pliers to
fold the tabs over the wire. Then use a crimping tool
(18-22 gage crimp) to crimp the tabs on to the wire. Do this for
tabs B and C. If done correctly, the pin should not wiggle back
and forth or rotate when some force is applied. The tabs should
be compressed enough so they will fit into the holes of the
connector. Note, if you do too much squeezing and crimping,
especially at tab A, the wire will break, which is an
undesirable situation. Once each of the pins are attached to the
ends of the wires, it may be desirable to do a continuity test
as above to make sure none of wires were broken during the
process of attaching the pins.
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Next the pins will
be pushed into the BACK of the connector as shown in this
diagram. Note that the front of the connector has the saw tooth
edge, the back of the connector does not. The back of the
connector also has small numbers by each hole to help you get
the correct pins into the correct holes. The front of the
connector does not have these numbers. Push the pin into the
connector until the flanges snap into place with a slight click.
The pin should not stick out the front of the connector. Once
all pins are inserted, another continuity test should be done to
make sure no wires have been broken. Place the test leads on the
pins that are now at the front of the connector. Use the front
connector pin configuration in the diagram to figure out which
pins belong to which wires. This diagram will also be useful for
other continuity tests that will be done later.
Once the testing is
done, squeeze the wires together at the back of the connector and
wrap a piece of duct tape around the wires, up to the plastic
insulation of the slat cable.
If a pin has to be
removed, due to a broken wire, use the wire or a nail to push the pin
through the front of the connector and then grab the pin with a
needle nose pliers and pull it the rest of the way out. Take a small
piece of wire and put a new pin on it and then splice the other end
to the broken wire.
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Please note the
following when connecting and disconnecting connectors from each
other. A male and female connector can only be connected in one way
because of the saw tooth edges on the front. Don't try to force them
the wrong way. The two fronts are pushed together. On the sides of
the front of the connectors are a hole (male) and a bump (female)
that latch together. It is best to push the connector together while
holding the connectors and not the cables. The first few connections
may require extra care to make sure the pins all line up and no pins
are getting bent. A little rearranging, pushing or pulling with a
needle nose pliers may be required to get them to fit properly.
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To disconnect the
connectors, squeeze the front of the connectors on the saw tooth
side and its opposite side. This force will cause the other
sides with the hole and bump to flex, which will unlatch them.
While squeezing, pull the connectors apart. Do not pull the
connectors apart by the cables or the cable may pull loose or
break.
This picture on
the left a top view of a 3 row x 5 column slat. At the
bottom of the picture, a slat cable exits the front of the slat
and the male connector at the other of the slat cable is
visible.
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THE BATTERY
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This firing system
uses a 12 volt, 7 amp hour/20 hour battery. It can deliver 12
volts (actually closer to 14) and 7 amps of power per hour for
up to 20 hours. The battery is sealed so there is no spillage if
it is bumped over. The battery requires no maintenance. It has
less amperage than a normal car battery so it is safer to use,
but is still sufficient to heat the igniters. This type of
battery is used in a small garden tractor and could probably be
purchased at a garden or automotive store. On the right is a
picture of the battery with the wires from the fire panel
attached. |
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CONSTRUCTING THE
FIRING PANEL
In theory, the firing
panel was designed to add an electric circuit each time a slat was
added. In practice, it is much easier to build the panel to handle
three slats and later expand to six or build the panel to handle all
six slats at once. All the slats do not have to be built at once, but
they can be built one at a time and then be plugged into an available
power connector on the panel. The directions for the firing panel
assume that the panel will handle either three or six slats.
Materials
(handles 3 slats)
- two 16" long x
3" wide x 1/2" thick boards (back & front boards)
- two 9" long x 3" wide x 1/2" thick boards (left
& right boards)
Note: As long as the
above boards are the same thickness, 1/2"-3/4" thick boards
can be used, but then the left and right boards would have a length
of (10" minus (2 times the board thickness)).
- one 16" long x
10" wide x 1/4" thick hard board (top cover)
- one 16" long x 10" wide x 1/4" thick hard board or
1/8" Plexiglas (bottom cover).
- 18 1.5 inch wood screws.
- 4 washers for wood screws.
- 2 #8-32 x 1" zinc Truss head machine screws
- 2 #8-32 zinc machine screw nuts (coarse thread)
- 6 #8 zinc washers
- 3 DPDT, center off,
switches 10A at 125VAC, 1/2" hole (Radio Shack 275-1553, www.digikey.com)
- 3 Red panel lights, 12 VDC, 10A-30A, 1/2" hole, wire leads (if
possible), (CALTERM 40410, at most automotive stores, www.digikey.com)
- 3 4 position, non-shorting rotary switches, 3A-6A at 125VAC.
Should carry 5A or more. Solder lugs with holes or screws (www.digikey.com).
Such switches can also be found here.
- 5 SPST push button (momentary on) switches, at least 6A at 120VAC
(Gardner Bender, GSW-22, Home Depot, Fleet Farm, www.digikey.com).
- 5 Twist-on wire connectors (blue, must handle four, 18 gage wires),
(Gardner Bender, 10-002).
- three 9-conductor female molded nylon (power) connector (Radio
Shack, 274-239)
- 7 feet 18 gage, 5
wire cable
- 5 feet 18 gage red hook up (bell) wire (Radio Shack 278-1217)
- 4 feet 18 gage black hook up (bell) wire (Radio Shack 278-1217)
- 2 Heavy-duty
alligator clips
- 2 feet 16 gage or thicker black wire
- 2 feet 16 gage or thicker red wire
- Duct tape
- Latex Enamel Paint, Porch and Deck Paint, or Fire Resistant Paint.
- 3/4" Vinyl "stick on" letters (HeadLine). This is
optional.
Additional
Materials (handles 3 more slats, for a total of 6)
- 5 SPST push button
(momentary on) switches, 6A at 120VAC (Gardner Bender, GSW-22, Home
Depot, Fleet Farm).
- 17 Twist-on wire connectors (blue, must handle 4 18 gage wires),
(Gardner Bender, 10-002).
- three 9-conductor female molded nylon (power) connector (Radio
Shack, 274-239)
- 7 feet 18 gage, 5
wire cable
- 2 feet 18 gage red hook up (bell) wire (Radio Shack 278-1217)
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Constructing the Firing
Panel Box
First the outside
box of the firing panel must be made. It will have dimensions of
16" long x 10" wide and about 3.5" high. On the
left board find the very center of the board and drill two
5/32" holes (B+, B-), each hole 1" to the left and right
of the center. This is for the battery terminals. Also drill three
3/8" holes (L4, C4 and R4) in the back board for the slat
cables to enter the box. They are 3", 7" and 11"
from the left edge and in the middle of the board (1.5" from
the edge). For a six slat panel, drill holes L5, C5 and R5
at 5", 9" and 13" from the left edge. At the
corners of the box, drill one (or possibly two) 1/8" starter
hole through the ends of the back and front boards into the left
and right boards. Then screw in the 1.5" wood screws. Click
image to enlarge.
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Note: From this
point on, all of the panel diagrams in this section can be enlarged
to produced a scaled version (0.01" per pixel,
16"x10"), which can be printed off to get a actual size
diagram. Printing at 8"x5" will give a
half scale diagram.
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Constructing
the Top Panel Cover
Next the top cover
of the box must be constructed. Place the top cover squarely on
the top of the box. Drill six 1/8" starter holes (S1-S6)
through the top cover and into the sides of the box. Screw in
1.5" wood screws. S1, and S5 are 4" from the left
edge. S2 and S4 are 4" from the right edge. S3 and S6 are
5" from the back edge. All holes are 1/4" from their
closest edge.
Click the
diagram to enlarge. The larger version is scaled
(0.01" per pixel, 12"x10"), which can be
printed off to get a actual size diagram. |
Next drill the DPDT
switch holes. Measure 2" from back edge and 4" from the
left edge and drill a 1/2" hole for the left switch (L1). Drill
the center (C1) and right (R1) holes of the same size each one
4" inches to the right of the previous. There should be holes at
4, 8 and 12 inches from the left edge.
Measure one inch below
each of those holes (3" from back edge) and drill a 1/2"
diameter hole for each of the panel lights (L2, C2, R2).
Measure 5.5" from
the back edge directly below each of the panel light holes. Drill a
3/8" diameter hole for each of the rotary switches (L3, C3, R3).
Note, most rotary switches need this sized hole, check the rotary
switches to see what size is really needed.
Measure 8" from
back edge and 1.25" from the left edge and drill the first
1/2" push button hole (0). Drill four more 1/2" holes, each
one 1.5" to the right of the previous hole (push buttons 0-4).
There should be holes at 1.25, 2.75, 4.25, 5.75 and 7.25 inches from
the left edge. For a six slat panel, drill five more 1/2" holes
(push buttons 5-9) to the right of the first five each one 1.5"
apart (8.75, 10.25, 11.75, 13.25 and 14.75).
At this point, any
exposed surface of the box, that does not have formica, should be
painted. If the bottom cover is hard board, it should be painted too.
There will probably have to be some touch up painting done after the
panel is finished. Otherwise, all the painting could be done when the
panel is done, but use care when painting near the switches and
lights. At some point after the painting is finished the rotary
switch positions should be labeled (A-L) as well as the push buttons
(0-9). The top and bottom of the toggle switches could be labeled
with "Test" and "Arm" to indicate which mode the
toggle switch is in. The labeling can be done with permanent marker
or stick on letters. It is also extremely useful to paint around the
switches and labels with long-lasting, super bright glow-in-the-dark
paint (Ultra Green, Glow Inc, www.glowinc.com).
This allows you to see the firing panel in the dark.
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Adding Switches
and Lights
Flip the box over
from left to right, so the bottom of the box is in view.
Look at the diagram (click it to enlarge). Warning:
since this view is of the bottom of the box, all the holes are
reversed from left to right. Screw the DPDT switches into the
R1, C1 and L1 holes. Push the panel lights into the R2, C2 and
L2 holes. Screw the rotary switches into the R3, C3 and L3
holes. Finally screw the push buttons into holes 0-9. Tighten
all the nuts for all the switches.
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Wiring the Panel
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Attach a heavy
duty alligator clip to one end of the red 16 gage wire.
Now put a machine screw (terminal) into the B+ battery hole.
There should be one washer on the outside of the box and two
washers and the nut on the inside of the box. Wrap the other end
of the red 16 gage wire around the end of the terminal on the
outside of the box. Note that the wire on the inside will be
between the two washers.
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Remove the back
board to make it easier to do the wiring. Get a length of red 18
gage wire that is long enough to go from about R5 to B+ with at
least an extra 3 inches. Strip a short amount of insulation from
the end. Wrap this around the bottom of the upper left
terminal of switch R1. Do not wrap it around the screw, but
below the screw (see diagram on left). Squeeze the wire tight on
the terminal with a needle nose pliers. Stretch the wire to the
upper left terminal of C1. Cut the insulation where it meets the
terminal, but do not cut the wire. Slide enough insulation down
the wire to expose enough bare metal to wrap it around the
bottom of this terminal. Squeeze the wire tight like the
previous terminal. Do this same process for the upper left
terminal of L1. Then stretch the wire to side of the box and
down to terminal B+. Strip the insulation off the end of the
wire and attach it to B+ as shown in a previous diagram.
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The diagram on the
right (click on it to enlarge) shows this red wire
running from R1 to C1 to L1 and then to B+. It also shows how to
wire the rest of the red wire. Connect the wire from the left
side of light L2 to the upper left terminal of L1. Use the screw
on the terminal. Take the wire from the right side of light L2
and run it to the left bottom terminal of L1. As you did before,
cut the insulation, expose some bare wire and wrap it around the
lower left terminal and squeeze it tight. Then stretch the wire
to the center right terminal. Strip the end of the wire and
attach it to the terminal with the screw. Finally attach a wire
to the screw on center left terminal and stretch it to the
common terminal on L3.
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Notice that L1-L3 are
wired the same as C1-C3 and R1-R3. So now wire C1-C3 and R1-R3 like
L1-L3.
Now the black wire will
be attached. Attach a heavy duty alligator clip to one end of black
16 gage wire. Now put a machine screw into the B- hole. Attach it the
same way that B+ was attached, with a nut and two washers inside the
box and one washer on the outside of the box.
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The diagram to the
left shows how the inside of the box is wired for black wire
(click it to enlarge). Get a length of black 18 gage wire that
is long enough to go from R5 to B- with at least 3 extra inches.
This wire will be attached
to the upper right terminals of R1, C1 and L1 just like the red
wire was attached to the upper left terminals of R1, C1 and L1,
but wrap the wire around the screw of the terminal and tighten
the screw. See the diagram on the right. The other end of
the wire is attached to the terminal B- like the red wire was
attached to B+. At this point, re-attach the back board.
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Remove the front board.
Get a length of black 18 gage wire that is long enough to go from
switch 4 (switch 9 for a six slat panel) to terminal B- with at least
5 (10 for a six slat panel) extra inches. Starting at the lower
terminal of switch 4 (switch 9 for a six slat panel), attach the wire
to each lower terminal of all the switches and then to B-. Use the
same technique used to attach the black wire to R1, C1 and L1. Then
re-attach the front board.
These pictures below
show the top and the bottom views of the firing panel, at this point
of the construction. In these pictures, please ignore the fact that
S3, S6, B+ and B- are moved about an inch off from the positions
described above.
Discussion and
Testing Circuits
Now that some of the
panel is wired, examine circuits L1-L3 to see how they work and to
test them. Cue A1 will be fired. Rotary L3 is set to row A and DPDT
switch is off (centered). There is an igniter attached to cue A1. To
test A1, TEMPORARILY attach an igniter wire from terminal A of L3 to
the upper terminal of switch 1. TEMPORARILY attach the battery to B+
and B-. Power comes from B+ over to the top left terminal of
L1. It also goes through the light to the lower left terminal and
then to the center right terminal. Since the switch is off, power can
not get to the center left terminal, so the whole circuit is open.
Push switch 1 and nothing happens.
Push switch L1 up to
put it in test mode. There is now contact between each center
terminal and bottom terminal (but not between each center terminal
and top terminal). Power comes to the left top terminal. It can't
flow between the top and center terminal. But it flows to the light
to the lower left terminal. Because there is contact, it will flow
from the left bottom terminal to the center left terminal. From there
it goes to L3 and out to terminal A. The temporary igniter wire
mimics an igniter on cue A1. Terminal A will be attached (it isn't
yet) to row A of the left slat via the row A wire that goes out
through hole L4. Power will go through an igniter and come back
through the column 1 wire that will (it isn't yet) go through hole L4
to the top terminal of switch 1. This will then go back to B- when
switch 1 is pushed, which makes a closed circuit. Push switch 1.
Light L2 should light, but the igniter will not heat up because L2 is
in the circuit serially. All the power is used by L2. If the igniter
is removed or broken, when switch 1 is pushed L2 will not light. This
is how cues are tested for continuity.
Push switch L1 down to
put it into on or armed mode. There is now contact between each upper
terminal and center terminal (but not between each bottom terminal
and center terminal). Power comes to the left top terminal. It flows
to light L2 to the lower left terminal. From here it can not reach
the center left terminal, but it flows to the center right terminal
and then to the upper right terminal. It then goes back to B- forming
a complete circuit. L2 should be on indicating a fully powered
circuit. Also note that power flows from the upper left terminal to
the center left terminal. This goes out to L3 and out to terminal A.
Then it goes through the temporary igniter wire to switch 1. Make
sure no body parts are near the igniter and MOMENTARILY push switch
1. The igniter should start to heat up and burn. Light L2 might dim a
bit. Because there are momentarily two parallel circuits the power
flows through the circuit with the igniter wire (less resistance)
instead of through the circuit with light L2. TURN OFF L1, REMOVE THE
TEMPORARY IGNITER.
Circuits C1-C3 and
R1-R3 can be tested like circuits L1-L3 by running igniter wire
between terminal E and switch 4 and between terminal I and switch 4
or 7. DO EACH ONE AT A TIME. REMOVE THE TEMPORARY IGNITER when done.
REMOVE BATTERY when done.
Adding the First
Three Connectors and Slat Cables
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This diagram on
the right shows the wiring of one slat circuit, but the red and
black wires added previously are erased to make the diagram
clearer. There is a female connector just outside of hole L4 to
which a slat cable is attached. The slat cable comes into hole
L4. It splits into the row and column cables. The row cable goes
to the rotary switch L3. The R1, R2, R3 and R4 wires are
respectively attached to the A, B, C and D terminals of rotary
L3. The column cable splits into separate column wires. Each
column wire is attached to a twist connector in the upper right
corner of the panel. Each of these twist connectors is attached
same colored wire of another column cable which goes down to
switches 0-4. Please note that this column cable is NOT
attached to B+ or B-, it just passes by them. The C0, C1, C2, C3
and C4 wires of the column cable are respectively attached to
the upper terminals of switches 0,1,2,3, and 4. Click
to enlarge.
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Wire the panel as shown
in the diagram. The female connector should be attached to the slat
cable using the same technique that was used to attach a male
connector to the slat cable. The connector should be attached to the
cable before it is fed through the L4 hole. Hole L4 may have to be
made slightly larger with a file or sand paper, so that the back of
the connector is almost flush with the back board of the panel.
The saw teeth of the connector should point towards switch R1, so the
sides can be squeezed for connection and disconnection. A continuity
test should be made. Use the "Female Connector Pin" diagram
as a guide. Stick the first lead into a hole in the female connector
and touch the second lead to the appropriate terminal where the wire
should be going to. So for a row hole, touch the second lead to
terminal A-D on the rotary switch and for a column hole touch the
second lead to the upper terminal of push button 0-4.
At this point, one
circuit is wired. One slat could be connected to the firing panel and
actually tested using the tests found in the next section ("TEST
YOUR FIRING SYSTEM").
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The diagram here
has two more circuits added. Slat cables with connectors come
into holes C4 and R4. The saw teeth of the connectors point in
the same direction as the L4 connector. The row cables go to the
rotary switches C3 and R3. The column cables go over to the
twist connectors in the upper right corner. Wire the panel as
shown in this diagram so the panel will support three slats. Do
a continuity test for all the holes in the female connectors as
was done for the L4 connector, but use terminals E-L for the row
cables. Use some duct tape to secure the column cable to the
side of the box. Also wrap some duct tape around the column
cables, just before they reach the twist connectors. If this
firing panel supports three slats, then all the wiring is done
and you can skip to the section labeled "Attaching the
Bottom Cover". Click it to enlarge.
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The picture on the
right shows wiring of the panel at this point. The female
connectors are seen at the top of the picture. The slats cables
come through the back board and into the panel box. The battery
cables are in view on the far right. Click image to
enlarge.
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This picture shows
a close up of the female connectors on the back board of the
panel. There is also a male connector attached to a slat cable
in view.
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Adding the Last
Three Connectors and Slat Cables
 This
diagram shows how to finish the wiring to support six slats (click
to enlarge). All the previous wiring has been erased to make the
diagram clearer. Female connectors with slat cables come into the
panel through holes R5, C5 and L5. Note: the saw teeth of these three
connectors should point in the opposite direction of the first three
connectors. The column cables for these slat cables go to the upper
left corner of the slat where each of the same colored column wires
are attached to twist connectors. A column cable is attached to the
twist connectors and the C0, C1, C2, C3 and C4 wires of this column
cable are respectively connected to the upper terminals of switches
5-9. As with the previous slat cables, the row cables go down to the
appropriate rotary switches and each row wire is attached to the
correct terminal. Note, if the terminals of the rotary switches are
unable to handle two row wires on them, add a short piece of red 18
gage wire to each terminal of the rotary switches. Add a twist
connector to the other end of the wire. Then attach the two row wires
to the twist connector. Wire the panel as shown in this diagram so
the panel will support three more slats. Do a continuity test for all
the holes in the three added female connectors as was done for the
previous three connectors, but use switches 5-9 for the column holes.
Use duct tape to secure the column cable to the side of the box. Wrap
duct tape around any cables just before they reach any twist
connectors. Wrap cables by the back board with duct tape and secure
to the back board of the box.
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This picture
is of the bottom of the firing panel after it has been
completely wired for to support six slats.. Click image
to enlarge.
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Attaching the Bottom
Cover
Once the desired number
of connectors and slat cables have been added to the panel, it is
time to close up the panel box. Attach the 16"x10"
hardwood board or Plexiglas to the bottom with four 1.5" inch
wood screws and four washers. One screw each should go into the
center of the back and front boards. One screw each should go into
the left and right boards, but they should be placed so as to not run
into B+, B- or the other screws coming down from the top cover.
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You may also
want to label the female connectors on the back board of the
box so it is easier to keep track of which connectors to plug
the slat cables into. This picture shows one way to label
them. The two connectors on the far right are for rows A-D.
The connector above the "A" is for columns 0-4,
while the one above the "D" is for columns 5-9.
Likewise, the two center connectors are for rows E-H. The
connector above the "E" is for columns 0-4, while
the other above the "H" is for columns 5-9. The two
far right connectors are for rows I-L. The connector above the
"I" is for columns 0-4, while the other above the
"L" is for columns 5-9.
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These last two pictures
show a top cover and back board view. The back board view also shows
a slat cable about to be plugged into the firing panel. Click
on the images for a larger version.
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TEST YOUR FIRING
SYSTEM
Here is a quick way to
test the firing panel and slats. Connect one or more slats to the
firing panel. Attach the battery. Set the toggle switches to test.
Start with the cue in first row and first column (R1,C0) of the slat.
Wrap igniter wire around one of the terminals and stretch it to the
other terminal and wrap it around. Test the cue from the panel to see
if the light goes on. If it does, repeat this for the cues at the
second row and second column, third row and third column, fourth row
and fourth column. Finally test the cue at the fifth row and first
column. If one of these cues fail, test another cue in the same row
or column to narrow down whether the row or column wire is failing.
Remove the appropriate connector, check the appropriate pin.
Manipulate it with a needle nose pliers. Reconnect and try again. If
it still fails do the continuity test from the male connect to the
slat. If this test passes try checking the continuity from the female
connector into the firing panel.
If the above tests
pass, then try the ultimate test. As above, hook an igniter wire
between the two terminals of a cue, but do it for all cues. Test a
cue to make sure it works, then remove the igniter wire and test to
make sure it does not work. This will test the diodes to see if they
are working correctly. Put the wire back on and do the next cue.
If all is fine, flip to arm mode and push a few cues to see some
igniters burn. When done, turn off switches and remove the battery.
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TESTING CIRCUITS AND
CUES WITH THE CONTINUITY TESTER
During on-site set up
of a show the continuity tester on the firing panel can be used to
test all circuits of all cues to make sure they will fire properly
during the show. This procedure will test all parts of the firing
system. The procedure works best if there is more than one person.
The tester sits by the firing panel. The firing panel has the battery
hooked up and ALL OF THE TOGGLE SWITCHES ARE PUSHED FORWARD TO TEST
MODE! One or more workers are out by the slats and fireworks,
hooking shooting wires to the fireworks. In this example, assume that
cue C3 is being tested. Below is the tests that will either pass or
fail. If the test fails, there are suggestions to fix the problem. If
the test passes, skip over the suggestions to the next test.
1) The worker calls out
"C3" to the tester. The tester fires the cue by setting the
left rotary switch to "C" and pushes the "3"
button. The tester calls back "yes" if the light above the
left rotary goes on and "no" if it does not. If the light
is off, the test passed.
If the light is on, the
test failed. Note, if the firing panel and slats are made properly,
this test should rarely fail. In practice, this test is usually done
for the first cue on each slat. After that, it can usually be
skipped.
First make sure the
both tester and worker are testing the same and correct cue. Maybe
the tester thought the worker said "B3". Maybe the worker
really wants cue C2, while C3 is already hooked up. Maybe the tester
looked at the wrong light on the panel. Check to make sure the slat
cable is connected to the correct connector on the firing panel.
Wiggle the connectors.
If there is still a
problem, then this is a big problem because there is a short in the
slat, slat cable, connectors or firing panel. Try plugging the same
slat into a different connector. If it passes, then that firing panel
connector is bad. Use that slat in a different firing panel
connector. If it fails, try plugging a different slat into the
original firing panel connector. If the test passes then the original
slat is bad, it should be replaced with another. If it fails, there
is something wrong with the firing panel and you have a very big
problem. You may have to do some of the tests in the previous
"Testing Your Firing System" section.
2) The worker connects
the shooting wire to the cue and calls "C3". The alligator
clips on the ends of the shooting wire should NOT be touching. The
tester fires the cue and calls back "yes" or "no"
if the light is on or off. If the light is off, the test passed.
If the light is on the
test failed. The worker should check to make sure shooting wire is on
the correct cue. The worker should also check to make sure the
alligator clips are NOT touching each other, touching any alligator
clips on other shooting wires or touching any metal surface. If the
test still fails, then the shooting wire has a short and should be
replaced.
3) The worker touches
the two alligator clips on the shooting wire together. These will be
the ones that are not attached to the cue. The worker calls out
"C3". The tester fires the cue and calls back
"yes" or "no" if the light is on or off. If the
light is on, the test passed.
This is probably the
most common failure. If the test fails, there may be a loose or
broken wire on the alligator clip. Re-attach or tighten it. If the
test still fails, the shooting wire may have a break in it. Try with
a different shooting wire. If it passes then the shooting wire was
bad, so use the new one. If it fails, then try the test on a
different cue in the same row and a different cue in the same column.
If they pass, start over with a different shooting wire. It this
fails then probably the whole row or column is out, then there is a
problem with that row wire or column wire. Probably the problem is
with the connector. Give it a wiggle, disconnect and check the pins.
Use a needle nose pliers to straighten, push in or pull out any
malformed pins. Reconnect and try again. If it still fails, try doing
the tests in the previous "Testing Your Firing System"
section.
4) The worker attaches
the alligator clips to the igniter. The worker should also make sure
the igniter is wrapped around the fuse. The worker should make sure
the alligator clips are NOT touching. The alligator clips should not
be touching any metal surface. The worker calls "C3". The
tester fires the cue and calls back "yes" or "no"
if the light is on or off. If the light is on, the test passed.
If the light is off,
the test fails. Either the clips are not connected to the igniter
properly or the igniter wire is broken.
5) After all the whole
show is set up, but shortly before the show starts, the person firing
the show should test all cues again in the order that they will be
fired in the show. This will catch anything that might have broken
during set up.
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SIMPLIFY THE FIRING
ORDER
When the show is
planned, it will simplify shooting and reduce mistakes if the show is
designed to use the simplest firing order with minimal switch
changes. The simplest firing order is to set all rotary switches to
the first row (A, E, I) and then fire all the cues for those rows in
column order (0-4 or 0-9). So for example, A0,E0 and I0 would be
fired at once, followed by A1, E1 and I1 up to A4, E4 and I4 (or A9,
E9 and I9). Then move to the next row on each rotary switch (B, F, J)
and fire all the cues on those rows in order. So three cues are
always being fired at once. If only one or two cues need to be fired
at once, leave the other cues empty. If more than three cues
need to be fired, place them all together on the same rows. Once the
first three are fired (which takes about a second and one button
push), it takes only a finger move to the next column button to
quickly fire the next three. It is also easy to keep track of what
button to fire next. After pushing a column button, just move your
finger near the next button to fire. When you get to the end of the
buttons, you then know it is time to switch the rotary switches and
move your finger back to the beginning.
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VARIATIONS
When designing this
firing system, I already had three slats with three rows and five
columns of cues. These were used with an earlier
firing system.
I designed the new firing system so these slats could be used also.
The row cable has three wires (18/3 thermostat wire) instead of four.
When adding a power connecter to the slat cable, the hole for 4th row
wire (hole 4) remains empty. This slat cable can be connected to the
firing panel, but the 4th row will not be available. Both 15 and 20
cue (4 rows x 5 columns) slats can be used at the same time.
If 4 position rotary
switches are difficult to obtain, three position rotary switches or
SP3T switches could be used instead. A SP3T switch is a three
position toggle switch than can be used like a three position rotary
switch. You would probably use an 18/3 thermostat wire for the row
cables instead 18/4 or 18/5. The disadvantage of this system is that
there can only be three rows on each slat, instead of four. The
fourth row hole of all the power connectors would be empty. There
would only be 15 cues on a slat instead of 20 for a total of 90 cues
on six slats. A modification to this variation would be to use
the 4th row wire as a 6th column wire. The firing panel would have to
made a bit bigger to hold two more push buttons. Each slat would have
3 rows by 6 columns for 18 cues on slat for a total of 108 cues on
six slats.
If five or six position
rotary switches are available, the blue (fifth) unused row wire in
slat cable could be used as another row wire. It would be attached to
the fifth terminal on the rotary switch. The 9 conductor power
connectors would be replaced with 12 conductor power connectors
(Radio Shack, male 274-232, female 274-242). The two center holes of
the connector would be left open and the 10 holes on the edges would
be used for the row and column wires. This would allow for slats with
5 rows and 5 columns or 25 cues per slat for a total of 150 cues on
six slats.
The firing system as
described above uses a 12 volt, 7 amp battery for power. In most
situations, this should be sufficient. If you need to have slat
cables longer than 100 feet and there is not enough power to fire the
igniters, you might consider hooking two 12 volt, 7 amp batteries
together serially. This would provide 24 volts and 7 amps of power.
Serial hook up entails connecting a 16 gage wire or thicker to the
plus pole of one battery and to the minus pole of the other battery.
The other unused plus and minus poles are where you hook up the
firing panel wires. The advantages of higher voltage are that
the igniters would heat up much faster, there could be longer slat
cables and there could be more igniters fired at once. In a test with
24 volts, an igniter heated up in under 2 seconds with 400 foot wire.
At under 100 feet, the igniter seemed to heat up instantaneously. But
there are disadvantages too. Theoretically, most of this system can
handle 24 volts and 7 amps. The diodes, machine screw terminals, 18
gage wires, power connectors, toggle switches, rotary switches and
push buttons are all rated to handle at least 24 volts.
However, the added voltage may wear out these parts sooner and may
void any warrantees. The 12 volt lamps burned much brighter and will
definitely burn out sooner. It may be necessary to use 24 volt lamps,
instead. Most importantly, 24 volts is more dangerous than 12 volts.
If you do use 24 volts, be very careful. Under no circumstances
should you hook this firing system to more than 24 volts. Do not even
consider hooking this to a 120 volt AC wall outlet.
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