HISTORY:
Working through more boxes of "old projects and spare parts" in the workshop, I have "retired" although I seem to be getting less sleep sorting this lot out than I used to when running the businesses!
Here is something from the dim dark past, a variable speed XENON flash unit
This module is the PCB board ONLY, the XENON tube is mounted onto the PCB
I also found a brand new spare tube, it is included and I think it could possibly be required .... please read on
SAFETY!
First up, you MUST know what you are doing when "playing" with this board. While the input is low voltage and not terribly troublesome, it's a totally different story at the XENON tube and surrounding components - voltages in the hundreds and thousands of volts can be floating around here, even when the power is turned off .... take great care! If you make a mistake and touch the wrong area when the board is "live" you will know it!
XENON FLASH TUBE MODULE
"Homebrew" not a commercial product or even from an electronic magazine design
Well constructed on "proper" fibreglass" PCB but with NO component or input/output/control designations, but a technician with medium skills can soon work out what does what.
I do NOT have the schematics (can't find them) so the new owner is "on their own" with this one.
This board is offered for the "experimenter", those with inquisitive minds who like to dabble and see how these XENON flash systems work.
It was a long time ago that I or one of the staff created/played with this module but I seem to recall it is remote triggered.
Components of interest on the PCB:
Xenon flash tube (completely un-identified) 115mm length x 6mm diameter
4N26 Optocoupler
555 multivibrator IC
AV brand 630V film capacitors
MJE2955 transistor (acting as a regulator)
3x TK brand 47uF 350V electro's
Metal film resistors used throughout
Small trimpot (on flying leads) is the flash speed control
TESTING:
This unit, along with the spare Xenon tube, has been sitting in a box for yonks so today I bought it out for a quick "look see"
I used 12V AC as the power input, this goes to a rectifier/transistor based regulator etc ... the board is not marked where to apply this AC but I have indicated the points on the photograph and it isn't hard to figure out anyway (follow the copper traces from the two centre pins of the bridge rectifier. I used 12V because it was convenient, it may be that this voltage is not correct either - can't remember!
Immediately upon apply power, there is 500V DC across the Xenon tube (each end) and then the module just sits there, although I can see a very quick pulse like "spark over" in a small hand wound inductor near the tube (part of the trigger system).
So, lots of voltage across the tube but not enough to create a flash (ionising the gas inside the tube) - now it could be the tube needs replacing OR the external trigger needs to be applied. I have not attempted to measure the trigger voltage point, I don't wish to spend too long on this and left it at that. A short very high voltage pulse should be presented to the tube, to ionise the gas and create the intense bright white flash of light. I am not even sure my multimeter can safely read such high voltages used to trigger the tube (2000V and above can be expected)
The trigger looks to be via a 4N26 optocoupler but I have not looked into this any further.
WARNING (Again)
Even though you don't see the bright white Xenon tube flash, 500V is nasty in anyone's language so be careful!
Once the 12V AC input was removed, discharging the voltage across the tube took around 10 seconds before it dropped down to zero voltage.
DIMENSIONS:
140mm Wide x 140mm Depth x 60mm Height
COSMETIC CONDITION:
USED
CLEAN
NO damage to the single sided PCB or any of the components
Stored safely in a small box with bubblewrap (mainly to prevent damage to the Xenon tube(s)
