Folks, a new idea for some blinky kit got legs last night, made me spend a few too many hours awake..
The Super Standard Strobe String. ( ok, so it needs a better name ).The Strobe String will be a string of high powered white ( or optionally blue or any other colour ) (500-1000mW) Leds, on a string. Spacing between "strobes" to be determined, but could be as much as 1meter, and the number of strobes on the string as many as 50-100. ( thats to be determined ). THe strobe string is a special use case of the WS2801 controller chip ( which we have all seen in use for RGB strings )..
All three outputs of the WS2801 are put in parrallel, tripling the current available to drive a LED. This on paper is 150mA. However the overriding factor in the WS2801 is more to do with how much heat it can tolerate before it cooks. Because strobes have a low duty cycle ( the percentage of time that they are actually on ) in the order of a maximum of 5-10%, we can safely "overdrive" momentarily.
Last night i hacked an RGB pixel, changed its operating parameters, connected a 1W pixel to it, and using our E16 controller, sent a specially constructed sequence to it to make it behave like a strobe. The good news is that some 7 hours later, the 1W LED is still flashing twice a second at 350mA without issue. Its nice and bright, and the chip is not getting hot. In fact for comparison i've set a WS2801 running an RGB led at FFFFFF ( white ), and its surface temperture is higher than the one running the strobe. Why? because its average power loss is significantly higher than the "bright strobe". I'm going to run this test for the rest of the week to see what happens, and see if it remains stable.. I'm optimistically confident it will however.
Now, thats as far as i've got. Before you all jump off and ask the "but" questions, theres some things you need to know.
(1) While this technically could be plugged into a "standard" SPI type controller ( such as the E16, TP3244 etc ), for anything other than very carefully constructed sequence material you would risk an accidental melt down of the pixels.. In the worst case situation, if you set all the strobes to be on 100% you'd cook everything pretty quickly.. the ws2801's would overheat, you'd need a huge amount of current to drive it all ( read large large power supply and BIG cable ).. This is not a situation that anyone could really tolerate..
(2) Becuase of (1) above, a Super Standard Strobe String will need to be connected to a controller that is configured to deal with the limits of the string, so it does'nt cook it. The nature of "strobes" makes it pretty much sensible for the controller to create the "random effect" of the strobe, so it looks like strobing rather than have to create this on litternally hundreds of channels in your sequencing.. A controller for the SSSS will therefor probalby just require 3 or 4 dmx channels to set the parameters of the string.. This is just a mind map right now, but i suggest that the channels will control;
rate: the average time between flashes on a given strobe
intensity: the intensity of the flash from the strobe ( yes these are dimmable! )
fill: the average number of strobes that can be on at a given tome.
Some good news; As far as our E16 controller goes, all that is required is a firmware change to cope with this. I can't speak for Tabor and Phils TP3244, but i'd suggest that they too could make the firmware changes to support the SSSS.
Next steps:
(a) I'm going to creat a few more "hack" strobes and wire them together, and run them for a week.
(b) shoudl (a) prove to be ok, i'll get some test strings manufactured for me in our china factory
(c) distribute a few test strings to the developers about the place, and get all the nessesary firmware changes made to kit as need be.
(d) work out costing, and do a "once only ACL special Co-op" for those than want so. After that you can buy my commerical ones..
or someone else can run a co-op
the stobes would come in an expoxy encapuslated body, like our RGB pixels, ready to be plugged in used... Comple.
Price.. Let me figure it out, but its going to be good.
