I don't know Mike , they mention the N suffix in many datasheet titles ( like the one you linked ) but do not actually mention it in the sheet, and everything in the sheet states the 4.7v minimum supply.

I recall seeing a post from the guy who wrote the wavehc library, about using the buffer instead of a resistor voltage divider ( as used in the adafruit first waveshield version )

I don't seem to be able to find that post now, but I might try the resistors tomorrow anyway..

This is a great example of where a simple constant current generator comes into it's own,  a transistor, led, and two resistors.  See my scribbled sketch :-  ( I still haven't mastered the inserting pics here  ! )

http://www.flickr.com/photos/johnandlyn/5506763085/

The bottom part is the actual circuit, the top part shows the calculations, the only critical component is the emitter resistor, which sets the current through the LEDs , and can be trimmed to suit.

The advantage of this circuit is that the current through the LEDs will be almost the same as through the emitter resistor ( minus the tiny base/emitter  current )

As long as the LED on the base is lit, it will have 2.1v on the base for a red LED, so the emitter will always have 0.7v less due to the base emitter forward bias, =  1.4 volts  ( in our example with a 2v1 LED and a 0v7 base emitter bias voltage )

This means that the transistor will always try to draw enough current through the LEDs in the collector circuit to maintain that emitter voltage, so if you pick the value of the emitter resistor to drop this voltage ( by Ohms Law ) for whatever collector current you require, it doesn't matter how many LEDs there are in circuit, or what the supply voltage is, you will get the same chosen current through every LED.  ( as long as there is enough supply voltage, and the transistor can handle the heat if the voltage is much higher than required )

I have scribbled some first choice resistor values for the three LED strip currents that you mention, but start with a 22 ohm say, and using a meter, put resistors across it in parallel until you get the current you want.

Using a red LED for the base reference voltage, rather than 2 diodes in series, is that the voltage/temperature drift of the LED cancels out the transistors drift  - ( I read somewhere back in the sixties, and it seems to work.)

I see that the one on the circuit states 74125N  which I cannot even get the specs of on the net ??

I dont know if this is the right place to ask this but I have been using the waveshield based circuit on some devices to play sound clips from a SD card.

One unit failed, and while faultfinding I see that from the circuit diagram that I sort of copied from http://www.ladyada.net/images/wavshield/v11/wave11schem.png  that the 74ls125 is used as a buffer between the 5v data lines from the micro, to the 3v3 SD card.

What I didn't notice was that the 74125 is powered from 3v3 ( the data sheet says min Vcc as 4v75 ? )

The inputs to the chip are 5v but the outputs are less than 2 volts.

I don't know if this is part of the trouble, I havn't got it working yet, but has anyone had problems with this ?

or I could connect the probe through a 3.9pF cap that I have in the drawer, its got 22pF caps to deck anyway.

the problem with the audio micro was a lazy crystal,  I stuck an LED ( and res) on pin 13 and loaded the chip with old faithful "blink.pde" and nothing happened, changing the xtal restored the blink...  You can't see it on the scope as the probe stops the oscillation anyway..

Contract? Whats that, this is Africa :-)
I have been consulting to these people for 8 years now with nothing in writing.

I made a prototype for this project last year using cmos chips for all the video side, and an micro for the audio ( using the wavehc library reading from a SD card )
They had a customer interested about 3 months? ago, but moved the goalposts by asking if I could do it with a function that queues the incoming numbers.

I said I could , but not with cmos logic chips, I would have to switch to a micro for the video. ( I also had some other projects to design and get into prototype stage during this time)
Thanks to this forum I managed to get the software working, and finally got a perf board proto running a couple of weeks ago. I designed the pcb over Xmas/new year, and received the boards last Friday ( all the factories close for summer holidays here over Xmas )

Meanwhile the company has promised delivery of four units by the 10th Feb!( the pcb just fits in a plastic box so that bits OK )

The more they ask me when the final one will be ready, the more I tell them there is no way of knowing, I said I hope by end Jan, but I always qualify this with if all goes well.   (They are non technical people and do not understand how difficult it is to give a time-line for R&D )

One director suggested I should have ordered all the components first ( like before I started designing it ! )

Of course, with the rush I made some mistakes on the track layout, and I have had a couple of OC tracks ( probably from all the flexing and poking around fault finding, breaking the pad/track)

And now I have a problem that the audio side just wont work at all, so I have to write a quick sketch to test that on its own.

And I still have to tweak the video switching circuit ( which i have on a daughter board as I knew it would need some experimenting )

I have had all 4 boards populated, so once I sort out the bugs, it should work out over the weekend, but I don't need this pressure - I am a Great Grandfather after all :-)   I should spend my weekends fishing and drinking beer !

I have been a few months on a project. ( as well as a couple of other simpler projects for the same customer simultaneously )

It is multi faceted, in as much as I am overlaying some text and graphics onto a Hi Definition LCD display  ( obviously it has to be synced to the incoming timebase, which was the first step )

This is partly micro based (Arduino software ), and partly 74HC chips to deal with the video speed .

I used one micro ( which I plug into the Arduino to program ) as the video controller , it deals with the vertical switching, the incoming wireless commands to say which number/graphic to display, and the enqueing of the commands in an interrupt routine , and the dequeing in the main loop.

A second micro handles an audio announcer, using the Wavehc library, to announce the same number displayed.

I have set it up so that when the announcer is busy, the incoming commands will be queued, and when its finished announcing, it will dequeue the next number , and display and announce each queued number in turn.

I made the mistake of telling the customer that I had the prototype working, and now they want four finished units by Wednesday !

Apart from trying to correct the mistakes on the rushed pcb, I now have problems ( I think ) with the software.

Several guys on this forum have been very helpful getting the software sorted out for me ( I only started Arduino late last year )

What is an average time to get such a  project to production?

Thats looking pretty simple now, and even though it needs an extra wire and an Arduino, it can be varied easily, my 555 one would need 70 tweaks with a screwdriver !   

G Morning , I am awake now and know exactly what you mean with the 10 clock pulses.

I didn't look at the posters link to another forum, and it looks like he will have a heavy power lead running to all the cameras, and as Crossroads says, they will be line abreast next to some equipment, so individual cables in a loom would probably be easy.

I am a bit thick here, I will try and work that out when I wake up, I dont understand the 10 bits.

I was suggesting only 3 wires + gnd and trigger looping through each camera.

If each camera has a flash, you could have a wireless version where the second camera counts one flash and shoots 10mS later, the next counts 2 flashes and so on. No RF or wires, but of course you would need a board and a battery at each camera.

Thanks Crossroads,
I will try that next time with the pics ( I'm half asleep 5am here )

With the wiring, we dont know his layout, but 70 wires in a gymnasium ?? 

Depending on the connector in the camera, he could build the chip into (say) a rca splitter.

Anyway, he has a few suggestions ,  now I like the idea of a wireless web 

Lefty-    now that sounds like a fun project for an Arduino !

Rob -  You need the 2 overlapping outputs, the 100mS  carrying on after the trigger has been passed on, how do you see that with the 4013?

true, but theres a lot of wiring that way, I was suggesting just a 3 wire daisy chain between all 70 cameras, with a chip on some perfboard in a matchbox sized box at each camera.
http://www.flickr.com/photos/johnandlyn/5402767011/

I havn't worked out how to put pictures in  

I don't know where zcream is, but I see that Radio Shack is charging $1.99 for the 556,   that's 5 times what I am paying in South Africa !