Andy on Wight

1, changing the connectors to a multi pin locking version rather than the D-Type currently being used

Defiantly a good idea D connectors really aren't up to rugged outdoor use. If cost is an issue I've seen old fashioned centronics type connectors used on some systems and while I've not used them myself they look to be a better bet (They have "fingers" rather than pins so no pins to snap off just before the display see
http://en.wikipedia....ki/Micro_ribbon
and
Centronics.jpg

Of course "Industrial" or "Mil spec" connectors are better but cost a lot more and you often need an expensive crimp tool to wire them up.

Work in that type of field so have access to all required crimping tools

4, audio warning of active firing as well as the original lashing LED on box.

With the option to turn the sound off for shows where you're sharing the firing position with sound, lighting etc. crew. Personally I can't really see much of a point to audio arm warnings an LED should be more than enough or maybe just an initial very short "BEEP" when the key is turned.

More of an additional item to the circuit,not a continuos noise either but just a serious of bleeps just so everyone is aware its ready to go.


5, getting the LEDs to switch off completely when iginitor fired.

That could be a double edged sword and lead to confusion over whether something has fired when in fact it hasn't. Of course good practice is not to assume anything but you have little control over who may use the desk in the future. You could have two modes, when unarmed it does a straight continuity check, but when armed the led state is "frozen" and the LED's are turned of on each button push. At the end of the show you switch back to "safe" and are given a continuity display again (although as has already been pointed out igniters can short once fired so an after show continuity check mustn't be relied on to check for misfires).

My biggest issue really, as far as continuity goes when fired they are high resistance and the test circuit sees them as 'gone' but during the display they are still on even if a lot dimmer. Have done a number of tests with the ignitors to try an solve it but no success so far

Good points, MFX, developing a system is to keep it as simple as possiblewhich means there are fewer things to go wrng but have a coupo,e of 'luxury' items to make it stand out the bit better.

BTW, 50mA test current would be considered a tad high, the igniter specs I've seen say a max of 10mA test current to ensure non-ignition. I would guess from your description of the igniters that they're Chinese, possibly from Cosmos, though that's not certain.

Sorry for the late reply but I had an interesting discussion with the crew that have been using the system I designed and built for them last year. It has been well and truely used in all conditions (beach, grass and on a private jetty all in rain etc) and has given them no major problems. Only 1 display not done due to the fact a liner's wash managed to wash the whole display over with 5 minutes to go as it was set up on a beach.

I will be getting it back soon to give it a service and overhaul as some of the connectors are starting to show their usage in wet conditions. Will be having a real good talk to them whilst it is being serviced to see if I can improve it in any way and give some of my thoughts to them such as
1, changing the connectors to a multipin locking version rather than the D-Type currently being used
2, reduction of test current as suggested by pyrotrev.
3, visual ignitor box activation
4, audio warning of active firing as well as the orignal lashing LED on box.
5, getting the LEDs to switch off completely when iginitor fired.

I will take some photos and then I can develop it further (they are after more than the current number of cues as they will be doing a few larger displays). Was thinking computer firing but that may be beyond my capabilities besides it means more to go wrong.

Thanks for the quick responses, with regards the ematches hmmm no idea they have been got by my friends from the supplier they use.

They have orange twincore wires attached with red covered ignitors with w green plastic sleeve that goes over them. About 3-4m in length with the ends prepared for stripping, I am afraid thats all I know.

Looks like I might have to do a little redesign so that the LEDs are driven by a transistor circuit maybe, out with the old electronics handbooks by the looks of it, been a while since I needed them.

Thanks again.

This may be slightly off topic but I believe it is relevant to the subject on hand.

I have got a firing box that I am developing for a group of friends that are doing displays. Now whilst the design works I am seeing something that I do not quite understand and I hope that you may point out something that I am missing.

The design is for a 48cues running of 8 channels of 6. Please excuse the desciption for the moment put I will get a drawing done as soon as I can, but by starting at the power supply in a power switch allows power to the box but not to any of the circuit a seperate circuit arm switch does this. Once the arm switch is active there is power, but current limited to 50mA, to the continuity test for each cue, each cue has test LED that lights up if the circuit is active This is then connected to a a pair of speaker connectors with a 1N5401 diode in line, then the fuse to the return connection.

Once the fire circuit keyswitch is turned, power to the push to make switch with its LED is limited to a max current of 3A. The LED is lit when there is a continuous circuit. When the button has been press and the fuse fired the LED will go out.

Now the problem I am seeing is that the button LED does not always go out once the fuse has 'fired'. Any ideas on what may be wrong would be appreciaited.