Shooting fireworks with a computer ?
This is the reason why multiple e-match's should only be wired in series and not parallel.
The firing modules that you connect the e-match to in all computer systems share the same source of power when it comes time to ignite the e-match, an electrolytic capacitor. When the main control unit is turned on it starts to charge the capacitor that is inside each module. It is similar to a photo flash for a camera. When you turn on the flash unit you can hear an oscillator giving off a high frequency sound as it charges the capacitor. When the flash goes off you can hear that high frequency noise again as the capacitor charges back to capacity again. If the subject for the photo is close the flash goes off but charges quickly and is ready again very soon. If the subject is far away the flash needs more power from the capacitor so it takes longer to recycle before it is ready again.
The power usage of a module is very similar to that of a photo flash.
When the energy to ignite one e-match is needed it can recharge the capacitor almost immediately. When you have multiple e-match's on one circuit, more power must be drawn from the capacitor to fire all of them so it takes more time to recycle the capacitor back to it's full charge.
So What Is All Of This Leading Up To ?
Without going through all the math, the capacitor in a FireOne Module stores about 18 Watts of energy. The capacitor in a PyroSeeking module stores 44 Watts of energy.
Now lets look at an example of 5 e-match's wired in series and then parallel.
According to Ohm's Law:
Resistance in a series circuit = Rt = R1 + R2 + R3......
Resistance in a parallel circuit = Rt = 1/R1 + 1/R2 + .......
There are many manufacturers of e-match these days but I like to use to original daveyfire e-match to base my equations on. I always calculate the e-match resistance at 2ohms and to be safe I always say you should use 2 volts to ignite it. These values are not absolute but they always gave me good results.
So if we wire 5 e-match in series our total resistance will be.
5 times 2 ohm for a total of 10 ohms.
If we wire 5 e-match in parallel then our total resistance is 5 times 0.5 ohms for a total of 2.5 ohms
The voltage I said for each is 2 volts so we need 5 times 2 volts for a total of 10 volts.
The energy needed to fire the 5 e-match is calculated by the following equation.
P = V squared
The Series Circuit = 100 volts = 10 Watts
The Parallel Circuit = 100 volts = 40 Watts
Ohm's Law and Mathematics DO NOT LIE it takes 4 times as much energy to fire 5 e-match that are wired in parallel than it does if they are wired in series.
This may help explain why those 2 shots of 5 e-match that were wired in parallel and cued to fire at the same time off the same module did not work.
About The Author: Dan Erdeljohn worked in the fireworks industry for over 20 years., both building shells and shooting shows until back injuries forced him to retire. Since then he works at home repairing computers and digital firing systems. If he could be of any assistance to you he can be contacted email , firstname.lastname@example.org or phone 513-505-9224.
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