Hello folks,
I work for a fireworks supply house (we sell supplies not actual fireworks) and I’ve been tasked with trying to prototype a CDU (capacitive discharge unit) firing system (my big mouth got me the job). I know only the basic of electronics, so please excuse my ignorance. We have a vender in china who builds the systems we sell and are having a hard time explaining what we want in the new version; the language barrier and lack of examples is slowing down the final product considerably.
After reading a similar thread on this board (https://www.electro-tech-online.com/threads/electronic-firing-system-for-fireworks.21046/) I thought I’d throw the question to you all see if I have as good luck as he did.
What I’d like to do:
The system need to have the ability to generate and send a short high voltage pulse (18 joules) to Ignitors in the field. The purpose of the high voltage (capacitive discharge) is that igniters are usually at the end of very long shooting wires 300-600ft of 28gauge phone wire is not uncommon. The igniters have a no fire current of 20ma and an all fire current of 2 amps. The actual resistance of an ignitor can very considerably by manufacture from .5ohms to more then 20ohms (normal is from 2-5ohms). The system will have 30 (or more) queues some containing many matches is series. Ideally the system would have 10 individual fire buttons and a multi position rotary selection switch to change between groups of queues. Safety is paramount and two actions are required to fire a match, such as keyed switch and power on/off. All circuits would need to show continuity by sending 15ma though each match to an led on the panel. Best case scenario when selecting the queue group via rotary switch a light near each fire pushbutton would light up of continuity was found. It would be great to build in some kind of short detection (a common and time consuming problem) but this may be cost prohibitive. The system should function on small (rechargeable) batteries perhaps 3 D cells (any number of standard sized batteries would likely be ok). Often in a show queues are fired in quick succession so the charging circuit for the capacitor would either need to be robust enough to charge several firing banks or quick enough to replenish them real time in a show. I should also mention we are just barely making a profit on the existing systems so adding to much extra cost would be prohibitive.
Ok, lastly it would be awesome if there was a way to retrofit our wireless systems with capacitive discharge output as they are 5v & 18v systems and not enough energy is available to ignite fronts of 10 matches in series. It would be great to have a simple circuit that could just be connected to the firing lines to give an extra boost of energy.
Any questions I can answer or… ?
-Brian P
I work for a fireworks supply house (we sell supplies not actual fireworks) and I’ve been tasked with trying to prototype a CDU (capacitive discharge unit) firing system (my big mouth got me the job). I know only the basic of electronics, so please excuse my ignorance. We have a vender in china who builds the systems we sell and are having a hard time explaining what we want in the new version; the language barrier and lack of examples is slowing down the final product considerably.
After reading a similar thread on this board (https://www.electro-tech-online.com/threads/electronic-firing-system-for-fireworks.21046/) I thought I’d throw the question to you all see if I have as good luck as he did.
What I’d like to do:
The system need to have the ability to generate and send a short high voltage pulse (18 joules) to Ignitors in the field. The purpose of the high voltage (capacitive discharge) is that igniters are usually at the end of very long shooting wires 300-600ft of 28gauge phone wire is not uncommon. The igniters have a no fire current of 20ma and an all fire current of 2 amps. The actual resistance of an ignitor can very considerably by manufacture from .5ohms to more then 20ohms (normal is from 2-5ohms). The system will have 30 (or more) queues some containing many matches is series. Ideally the system would have 10 individual fire buttons and a multi position rotary selection switch to change between groups of queues. Safety is paramount and two actions are required to fire a match, such as keyed switch and power on/off. All circuits would need to show continuity by sending 15ma though each match to an led on the panel. Best case scenario when selecting the queue group via rotary switch a light near each fire pushbutton would light up of continuity was found. It would be great to build in some kind of short detection (a common and time consuming problem) but this may be cost prohibitive. The system should function on small (rechargeable) batteries perhaps 3 D cells (any number of standard sized batteries would likely be ok). Often in a show queues are fired in quick succession so the charging circuit for the capacitor would either need to be robust enough to charge several firing banks or quick enough to replenish them real time in a show. I should also mention we are just barely making a profit on the existing systems so adding to much extra cost would be prohibitive.
Ok, lastly it would be awesome if there was a way to retrofit our wireless systems with capacitive discharge output as they are 5v & 18v systems and not enough energy is available to ignite fronts of 10 matches in series. It would be great to have a simple circuit that could just be connected to the firing lines to give an extra boost of energy.
Any questions I can answer or… ?
-Brian P