What's changed?

1. Simplified External Trigger Protection - A single 1N4001 diode and two resistors protect the microcontroller from most causes of damage.  This protection circuit is cheaper and simpler than the V1.1 circuit, but much better than the V1.0 circuit.

2. Solid-State Relay (SSR) Boost Control - Instead of the complex circuitry introduced in the V1.1 design, a single component is used to turn the high-voltage boost converter on and off.  The voltage drop on the load side is about 200 mV when driving the boost regulator, while it only uses less than 50 mA to run.  This is much better than earlier control circuits.  A number of SSR's will work, but I recommend the Vishay VO14642AT ($3.81 CAD on Digikey).
3. Single Control Board - With the SSR mounted on the main control board, there is no need for a second control board for the boost converter.  This simplifies both construction and the wire routing inside the case.
4. Pre-Built Control Boards Available For Purchase (SOON) - I've prototyped a control board and will have a small number manufactured soon for those who are interested in building a flash.  I hope to keep the price low with a slim profit margin to support my continuing experimentation with the LED's.

What else is going on?

Development of the Mark 2 is ongoing.  The control board has gone through several iterations, a handful of LED's have been destroyed with the powerful new circuitry, and I only wish that I had more time to devote to its development :)

I'm also working on organizing an overview of my experiments for those who are interested in all the details.  The setup and results will be shared, likely on my website (www.td0g.ca).

NQTRONIX has sent an active light probe which arrived a few weeks ago.  Sadly I haven't had time to experiment much with it, but hopefully soon I can begin collecting data to answer a number of questions.  I've built a crude integrating sphere to use with the probe.  Here's a teaser from the fooling around I've done so far:  The LED's appear to turn on REALLY REALLY fast and turn ALMOST off JUST AS FAST.  My claims of sub-microsecond pulsing will soon be proven with some oscilloscope traces!