Do bear in mind that this will have the fraction of the power of a regular camera flash.
50 of those white LEDs have a combined input power of about 3.5W (not including resistor losses). A typical camera flash has an input of around 45w per flash. I think you'll find that while quite bright, those LEDs would not light a room to the same degree, or to the same effect (LEDs are much more directional), as a xenon flash.
Also note that magnatro's schematic shows the LEDs wired in series - you would need to wire them in parallel.
Also for the LEDs you have chosen, you will need a 12v supply.
Magnatro, in your schematic of post 6:
- There is no purpose of inductor L1? For a brief pulse of light, the inductor would limit the rise time - surely the flash would be better without it. Adding a capacitor might be a better option if your battery cannot provide a big pulse.
- Pin 3 of the first 555 timer should connect to pin 4 of the other, with 8 on both going to V+. This is the correct way to link two 555s - pin 4 is the reset. Your method is overly complex - also T2 would need to be a PNP transistor for it to work.
- Pin 2 of the first 555 timer needs a pullup (10K should do) to V+.
- The LEDs at the output should be in parallel, and each MUST have a protective resistor. Wired in series, they would not light (especially white LEDs, with a high Vf).
In the schematic in post 16:
- The same issue with the inductor.
- Pin 4 of the second 555 must be high for it to work - the best way to do this is connect it straight to pin 3 of the first, then connect pin 8 of the second to V+. With pin4 floating, the circuit won't work.
- Pin 2 still needs a pullup
- A piezo is the wrong component for SG1 - you need a buzzer (with a driver built in). A piezo would make no sound.
- C7 will stop any DC current getting to the second 555 - it will stop the circuit working.
- Your T2/T3 wiring is wrong (and some NPN/PNP confusion), but they are not needed anyway.
- The same issue with the LEDs and lack of resistors - in your circuit, they would not light up.
Andrew