Waterproofing electronics . . .

How would I set about waterproofing the electronics above the panel and below the panel in this small fireworks firing system ?

Inside it is all digital - there seem to be no 'mechanical' parts or relays, the only part that seems to require movement beneath the panel is the keyswitch.

On top of the panel there is of course the keyswitch and the speaker terminals - these are soldered to a circuit board inside the unit.

I have been having water ingress problems with this unit causing it to fail - not good when firing a professional firework display.

I cant just fill up below the panel with anything as it contains the rechargeable battery which may need replacing at some point.

I need to seal all of the electronics below the panel so that water entering via the keyswitch or speaker terminals or LED or switches etc cannot effect the operation of the unit.

Any ideas ?

Thanks

Gerry

Edit - The box itself is waterproof when closed - but in use it cannot be closed as the electronic ignitor wires overhang the edges of the box and would be cut off . . .

I think that you have a problem here.

The basic case (looks like a PeliCase) is ideal, but, that panel which has to be exposed to operate the unit is a disaster!

You may be able to "seal" the circuit board using something like this:
RS | Workshop Consumables | Paints, Lacquers and Corrosion Control | Protective Coatings | Lacquers & Varnishes
(I hope this link works), a spray on sealer which will stop the water contacting the circuit parts..

Also consider that although you may be able to seal the circuit board sufficiently, if water get inside the case, it will stay there.
Each time you use this in the rain, it would be a good idea to open the unit and let the insides dry out.

JimB

Hi - thanks for that, it is a Chinese 'copy' of a Peli case, so is fine when clipped shut, but as you say - is a disaster when the lid is open !

I think it would be too much hassle trying to waterproof it - and again as you say - anything that does get in has to get out somehow - so waterproofing it would be a recurrent excercise !

I think maybe my best option would be trying to figure out how to get the terminals extended outside the box.

If I could get - say - 10 terminals onto 2 boards - I could then have more flexibility in where I can place the box itself, as at present it - of necessity, has to be amongst the fireworks for their ignitors to plug into it.

I could fit 2 of some sort of connector (waterproof ) into the lid that would accept 10 pairs of wires, then wire from these connectors to 2 of sets of 10 more speaker terminals at the end of some sort of cable.

Does any of that make any sense !

Then I only need to open the box to check for continuity, arming the system with the key and so on.

So - in summary.

How to extend the 20 internal speaker terminals to the outside of the box as 2 lots of 10.

How to make the connection from the terminals inside the box to the terminals outside the box.

Electronics is not really my thing but am asking here for advice before I destroy anything !

I should be ok soldering wires to new connections but tampering with electronics inside the box itself is beyond my abilities.

Thanks

Gerry

Don't try to waterproof it.

Just build and place a simple frame over the whole setup and use some transparent sheetings over the frame to block out the rain.

Pour wax from a candle over the circuit sections that need waterproofing.
Miguel.

If you insist on pyrotechnics in the rain, what's wrong with using a small tent or canopy for the thing? As mentioned, all those connectors are killers for sealing. Even if you had them mounted outside the confines of the front panel, they'd be killers. For connecting wire, a simple binding post panel can be made waterproof and will probably provide superior connectivity over those Chinese speaker connectors. Most, if not all of those components on the unit are not designed for watertight integrity, hence the watertight lid.

Dean

It's not so much me insisting on pyrotechnics in the rain, but - as over the last week - clients book displays and if it's raining then we get wet !

Tents and canopies are no use - space is very tight, and the maximum distance normally between the firing box and attached fireworks can be as little as 12 feet - dictated by the length of the tails on the ignitors in the fireworks.

Canopies / tents and plastic covers and flame and sparks do not mix too well, hence my thought to extend the connectors to the outside of the firing system. It cannot be too far away from the actual fireworks, else wire resistence causes problems for satisfactory ignition of the ignitors.

If I was able to make up two seperate banks of connectors attached to the firing box - then it would be easier to waterproof these, it would be more flexible in how I could layout the firing site, and I could use a heavier gauge cable between firing box and new connectors to cut down on resistence.

I shall have to have a search and see if such a thing as 20 core cable exists ! as well as a suitable waterproof connector for whatever cable I find.

Needless to say telephone / data cable will not be rugged enough, and it would have to be a stranded core not solid to withstand repeated coiling and uncoiling.

I think . . .

Pyromaniac said:

I shall have to have a search and see if such a thing as 20 core cable exists ! as well as a suitable waterproof connector for whatever cable I find.

Needless to say telephone / data cable will not be rugged enough, and it would have to be a stranded core not solid to withstand repeated coiling and uncoiling.

I think . . .

Click to expand...

hi,
Multi core cable at 20 cores [and more are available] 7/0.2 Cu, tinned and screened overall with outer PVC sheath.

**broken link removed**


Multicore | CPC
Make sure you dont get less than 7 strands at 0.2mm dia.

Could you cut a hole in the cover above the display and put in a sealed Lexan window to view the display with the box closed? If so you could then add a waterproof connector for the pushbutton and switches. Those could be placed in a small sealed box for control. You could then keep the case shut. There is no way to seal the 'speaker' connectors unless you are willing to switch to binding posts or something of that nature.

Dale

You should use some type of enclosure or box that:

>> Is watertight, at least from the top and sides
>> Has a "door" on one of it sides (or eventually on its top) to access the connectors, (and if you keep everything in the same box) display and buttons. There should be a rubber gasket arround the door openning.
>> Has an opening on the bottom side to pass the ignitor's wires
>> Has some "legs" to keep the bottom opening away from the floor.

This way, the wires enter from the bottom of the box and the water keeps outside.

Look at the type of boxes that the telephone companies use, on top of poles, to splice the single pair wire that goes into a house to the multipair cables.

Waterproof multipin connectors are available from Digi-Key and others. Just search for waterproof connectors. They come in both circular and rectangular types.