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How do I build an extremely cheap, easily mass produced delay for my fireworks effects? Answered

I want to build a delay I can put in-line between fireworks effects. It needs four positions(0 sec, 0.1
sec, 0.25 sec, 0.5 sec), 'power in' connections, and power out connections. We use 22 gauge wire for our power feed from a 24V source. I am looking to make these delays no larger than 2"l x 2" w x 1.5" h not including the delay set knob. As an example - Instead of 10 comets firing off at one time, the delays would allow me to set them off, say, half a second apart. Is there a cheap reliable product already out there and available? Can I take resistors of different ohms and just twist them into the wire?  Thanks for your assistance!


Sounds like what Jayefuu and Seandogue suggested is pretty much the sequencer you already have.
I'm sure either of those guys (or any number of the other electronics gurus) could help you figure out how to rig up a transistor, a capacitor and a resistor or two to build your devices. I'm not an electronics guru, or I'd do it myself.
As an alternative, have you considered a low-tech approach? Like possibly lay out your run for simultaneous ignition, but instead of running the ignitors directly into the effects, put the ignitors into a bit of fuse and use different lengths of fuse to achieve the delay? Or something similar that's more legal/practical/safe?

Thank you. For my next trick, I will create cold fusion using a Mason jar, a votive candle, and a small bag of store-brand kitty litter.

So just to clarify, you want a "box" that you push a button. It has 10 outputs and a 24V supply.Once the button is pushed you want it to supply current to each of the outputs in turn, with a configurable delay.

In my opinion you've got a couple of options. The easiest would probably cost you no more than £20 and would be easy to set up. You could use a microcontroller like an Arduino to control some relays, as it couldn't provide the current i suspect you'll need to trigger the fuses.

Your second choice would be to build a circuit from ICs. Stuff you should research would be use of a 5V voltage regulator (to create a stable voltage for the ICs), use of a 555 timer to make an astable(this gives you a continueous on off, on off), use of a d-type flip-flop to create a serial in, parallel out shift register (to set off the relays one by one). A website like allaboutcircuits would be a good place to start.

If you want more help I'd be happy to help you with diagrams etc., perhaps the easiest way would be for you to set up an instructable to outline what you want to do, then add some collaborators, people that respond to this answers page, who would be willing to help you out.

   To clarify- I want to space my comets 5 meters apart in a straight line. Each comet will be connected to the comet before it with 5.5m of wire. I would like to build delays that mount to each comet. We have a piece of equipment called a sequencer that has a delay built into it and up to 64 connections. For me to use this device would take 385m of wire. A waste in my book when I might run only 55m or 60m at achieve the same effect.
                                         \                             \                           \
                                      comet                    comet                 comet

Does this diagram help?
Will the delays need their own batteries to keep the queue going?

In which case, the simplest and cheapest way would be to design a PCB and get it manufactured. On this you would have a 555 IC configured as a monostable. You would choose the delay on that with a rotary switch which would change a resistor value. When it recieves current along the wire, it waits the length of the delay and then closes a relay to trigger the comet and start the timer on the next one.

What's your budget per delay unit? They would of course be reusable. PM me if I forget to check back here for your reply. :)


   My budget is "as cheap as possible but still reliable and reusable". Would the delay unit need its own battery or would I need to leave the power on to the delay? Our wire isn't really heavy enough for constant energy I think. It is more for sending a pulse down the line to fire the effect.

Shopping list per unit so far:
   555 IC as monostable

a slow speed clocking circuit, a counter chip, a multiplexer, and a bank of mosfet opto isolated relays. done