Pyro Universe Store: T-shirts

Joe Zastrow's Firing System

000

Pyro Universe reader and fellow fireworks nut Joe Zastrow has come up with a more advanced firing system based off of the design on this page. Unlike my 20-cue system, however, Joe's 45-cue firing panel uses "slats" out on the firing area, which are like miniature control panel "substations". Rather than running 15 sets of positive and negative wires from the main panel to the fireworks - which can be time consuming and frustrating - this type of system has only a few large bundles of wires that run from the panel to the fireworks. There, they connect to the "slats", which splits up the main wire into three groups of five +/- lugs, which eletric igniters can be directly attached to. Confused? Just continue reading on to see what Joe has to say about his neat firing system. Below the pictures and general description is a more detailed section on the wiring (including schematics) in case you want to build such a system for yourself.

My firing panel supports 45 cues. There are three slats with 15 cues each. The picture of the left, shows the top of the firing panel. You turn on one or more letter switches and then push a numbered button. A, B, C, control the left slat, D, E, F control the middle slat and H, I, J control the right slat.

If you want to do one cue at a time, you can turn off all the letter switches and then switch in the rotary switch. You then move the rotary to the letter you want and then push a numbered button. It is much faster than turning on/off letter switches and prevents you from accidentally leaving on some switches on that you intended to turn off. You can still turn on the other letter switches if you need to do more than one cue.

The on/off/test switch is a DPDT switch that will let you turn it on, off or test mode. Test mode lets you
test the continuity of each cue. The power light will light up if you have continuity when you fire a cue, but it won't actually have enough power to ignite the igniter. You can't tell from the picture, but all the numbers, letters, switches and buttons have glow in the dark paint on them or around them. I bought some 8 hour EXTREMELY bright paint from GlowInc. The stuff works REALLY well! If it is dark, I see the glow in the dark paint. If it is light (from fireworks blasts), I see the black
letters and numbers. I HIGHLY recommend this for painting a firing panel. I talked with the owner of glowinc on the phone. He is a pyrotechnician too. He was very helpful. He is a officer of a large fireworks club on the east coast.

This picture shows the panel turned upside down so you can see the inside wiring. Notice that it has a plastic see-through bottom. It really impresses most people when you flip it over and show them the inside. The plastic bottom keeps curious fingers from accidentally getting shocked. It also allows you to hold the panel on your lap, with no fear of getting a shock.

Click here for a larger version of this picture.

To the left is a top view one of the slats (left slat). Each cue has a letter/number combination that refers back to the switches and buttons on the control panel. I use two wire thermostat wire (18 gage) with alligator clips on both ends (4 clips) to connect the cue to the firework igniter. Though, shooting wire would have worked just as well, but the thermostat wire was easier to obtain. You hook the two clips to
the two cue pegs and hook the other two clips to the igniter wire of the firework. It is really fast. The igniter wire is 31 gage nichrome wire wrapped around the fuse a few times, just like you suggest in your article. No e-matches!
The wire just heats up real fast (under a second) and the fuse lights.

To the right of the slat, is the two cables used to connect it to the control panel. It is two thermostat cables, one has three wires (for A, B, C) and the other has five wires (for 1,2,3,4,5).

The picture on the right is the inside of the slat. The little gray spheres with wires are diodes that I used to keep the electricity from firing other cues, once the igniter burns up. The blue knobs are just quick twist wire connectors.

The slats and some of the firing panel are made out of a piece of an old formica counter top. Originally, I did this to have a smooth surface and to cut down on sanding and painting. But it has one other benefit. Formica resists heat and burns. After a shoot, it does not matter how much sparks and soot has landed on the slat. It always wipes off!

If you are interested in building this system, read on: Joe explains more in-depth how he built his system.

Here is a partial diagram of the panel. All the wires in the panel are 14 gage. I left off switches D-I to make it simpler to see what is going on. The positive wire comes in and connects to one side of all the wall switches. It also attaches to one pole of the DPDT switch and to the switch that leads to the rotary switch (optional). The other side of the wall switches go out to the rows A-I of the three slats. In mine, A-C goes to the left slat, D-F to the middle slat and G-I to the right slat. The negative side goes to the On/Off/test switch. From there it goes to the momentary button switches. This then goes out to the columns of the slats. Note, if you have several slats, you will have 1-5 going to each slat. Note the rotary switch that comes from the positive side. Each of the poles goes to the outgoing rows A-I. In my panel, I actually ran the wires to the quick connect of each of the wall switches.

This saved me a bit of wire and it made good use of the connector. I use a 12 V, 7Ah/20HR battery. In other words, it will delivery 12 volts with 7 amps, for up to 20 hours. This is enough voltage and amperage to heat and melt 31 gage nichrome wire. I use 5 ply thermostat (18 gage) wire to run 1-5 column wires to each of the slats. I use 3 ply thermostat wire to run A-C row, D-F row, G-I row wires to to the left, middle and right slats (respectively). So you have two cables (a 3 and 5 ply) going to each slat. The cables are about 35 feet long, because I just have safe and sane stuff. I think you could easily make them 50 feet and there should be no noticeable degradation of heating power. The thermostat wire is available in most home builder or hardware stores. Though, the 3 ply is less common than the 5 ply. The wires are permanently attached to the slats. The other end of the wires have ring terminals. These then can be attached to bolts on the side of the control panel. This makes storing easier and you don't have to use all the slats if you don't need them.

Now on to the slat. Each set of gray dots are the poles or bolts for each cue. My shooting wire is attached to these poles. I have alligator clips on each end of the shooting wire. Actually, the shooting wire is 18 gage, two ply thermostat wire. I bought a 500 foot roll of wire. I cut it up into 30 pieces of 8.5 feet and 15 pieces of 16 feet for 45 pieces (45 cues) for a total of 495 feet. Each pole for each row is wired together. The other pole for each column is wired together. But each of those poles has a diode attached to it. This prevents the electricity from going "backwards" and through the circuit and firing other circuits. The best way to see this is to assume that A1, A2, B1 and B2 are attached to a firework.

In other words, the poles are a closed circuit. Also assume there are no diodes. If you fire A1, it fires and the A1 cue is open. If you hold the button down for more than a second longer, electricity travels to the red side of A2. It crosses over to the black side of A2 and travels down to the black side of B2. From there it crosses over to the red side of B2 and back to the red side of B1. It cross over to the black side of B1 and then back up to the black side of A1. This makes a complete circuit firing A2, B2 and B1 even though you are pushing A1. This is also multiplied in numerous other combinations so depending on what cues are open or closed, you could be firing all your cues. YIKES! The diodes prevent this from happening. They only allow the electricity to go in one direction. They prevent the electricity from going into the black side of the poles, but it can come out of the black side of the poles. You have to make sure they are connected right or it won't work. Each diode has a line on one side of it. That line corresponds to the line on the diode symbol. Each diode is a 3 amp, 400 Volt diode. You can pick these up at most radio shack or electronic stores. Actually, I could have used a 3 amp, 50 volt diode (since I am only using 12 volts), but these ones happened to be on sale. I used ohms law to get a guesstimate on the amps. Since there is so much wire and nichrome wire resistance, 3 amp works fine, even though up to 7 amps (see battery above) could be running through the circuit. Also the amps are only applied for a short time when you push the buttons. The 6 amp diodes are huge and they are definitely overkill. The store manager thought I could get by with a 1 amp diode, but I didn't want to try it. I would like to expound a bit on the number slats and the number of rows and columns on each slat. You need to have one wire for each row and each column on a slat. I used 3 and 5 for a total of 8 wires which gave me 15 cues per slat. It was easier to do that because one cable was the rows and the other the columns. I could have used 4 wires for rows and 4 wires for columns (still 8 wires) but it would have given me 16 cues on the slat (one more cue per slat). Or I could have had two wires for rows and six for columns for a total of 12 cues. The point is to use to 1/2 of the wires for rows and 1/2 for columns to get the most cues for your wires. The is a similar rule for the number of slats you have. The fewer the slats the fewer the number of wires you need, but you will probably need more shooting wire. For example, say I have 4 cables with 5 wires each. This gives me twenty wires. If I run them to one slat, I can then have 100 cues on the slat. But then I will probably need more shooting wire to reach all my fire works. If instead, I have two slats with ten wires (two cables) going to each slat, I can have at most 25 cues (5x5) on each slat for a total of 50 cues using the twenty wires. I have fewer cues, but I can place a slat on each side of my show and use less shooting wire. I will also use fewer switches. In the first case I will need 10 wall switches (rows) and 10 button switches (columns), while in the second case I could have 10 wall switches (rows) and 5 button switches (columns). I ended up with three slats because I wanted a slat on the left, middle and right because I tend to design shows that fire from three areas. If your shows are more symmetrical (as you show on your web page), you may want to opt for two slats. If I were to do this over again, I might be tempted to run 10 wires to each slat. The 5 ply cable was actually cheaper when you considered the cost per wire in each cable. I would have 4 rows and 6 columns (24 cues) on each slat with three slats (72 cues). I would use two DPDT switches to control the four rows of each slat (A off B, C off D, etc.). This would give me 6 six DPDT switches and 6 push buttons. I would have to ditch the rotary switch, since a twelve pole switch would be hard to find. But then again maybe I would have only two slats for a total of 48 cues (8 rows x 6 columns). I could 8 positions of my rotary switch for rows A-H and then use my ninth position as an OFF position.