The Shop > Electronics & IC Programing

Mad strobe?

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awemawson:
Spinning disk technology was in at the birth of television, invented 6 miles down the road from me in Hastings:

http://www.kevinhadfield.co.uk/mechtv04.html

PekkaNF:
I was thinkking of a 1kW halogen light on a well ventilated box, opening on the front and pretty close to it a spinning shutter disc  AC induction motor connected to a mains frequency (specially on three phase) should produce pretty accurate timing.

Then you need a SLR type curtain to run trough line of the light...ever wanted to build a 100x SLR shutter :lol:

If you build a plate shutter that drops by gravity and it is released with a solenoid, simply wired to your string release trigger.

That should produce completely "mechanical" solution. You need huge amount of light to "stop" motion. We had a high speed camera and we needeed room filled with a light, it was so bright that sunglasses were a must.

Wellcome back.

Pekka

vtsteam:
Andrew, great reading!

Pekka, I think the cooler LED's fully illuminating the subject with each pulse will be easier to do, plus I'd have control over all kinds of things like number of pulses, duration, frequency -- even non-linear pulsing -- logarithmic variation, for instance.

I better give you-all the point of this. Mainly to understand how much energy the arrow is getting from the limbs and string at intervals along the path through the bow. Nobody can predict that for sure. And it depends on the inertia of the arrow and the speed of the limbs. If the arrow has low inertia (a light arrow) and the limbs aren't fast enough, it's possible that the arrow gains energy only in the early part of the cycle or even outruns the string. Bows also don't act as uniform springs -- their rate, draw weight,  and internal resistance (hysteresis) varies along the draw length. If a bow pulls back easy at first but increases rapidly near full draw, that is called "stacking". A high stacking bow and a light arrow will behave differently than a bow that stacks less or an arrow with more mass that accelerates slower.

Anyway I want to see all this, and stop listening to endless internet conjecture about it. A picture is worth a thousand words,as they say, and a lot of pictures must be worth even more!  :)

PekkaNF:
I hear you.

Sounds a lot like BS about fly rod "action" and other properties long time ago. And there was info available, but a bunch of self apointed gurus figured they could brak the laws of physics with ignorance and repeating irrelevant analogs ad nauseaum.

I thought that you would like analog solution, few pictures of you shooting arrows next to steam punk "time slicing apparatus" and you could sell your bows to hipster and your retirement would be secure.

Anyway, I found one site some time ago that might have few interesting consepts:
http://www.doc-diy.net/photo/smatrig/

That site has some interesting triggering info that you migh find entertaining.

Anyways, I found that when I was searching means to make external trigger amplifier for oscilloscope.

I never considered LED flash, I'm aware that there are LED video lights and flash lookalike videolighths available (seen them in supermarkets), but your mail made me think that LED can deliver pretty high output levels when pulsed. And I have (or had) old Metz that gave pretty good strobo, but with reduced intencity.

Search revealed stuff like this:
http://www.led-video-lights.com/on-sale-new-zflash-dimmable-led-video-camera-light-plus-speedlight-flash-for-camera_p789.html

800 lux, is not much....specially that way spesified.

You are planning to use external trigger for camera to triger it and then flash to give burst of timed flashes?

How you are going to trigger your camera? Electrically from string release trigger?

Pekka

vtsteam:
Hi Pekka, I haven't put too much time into thinking about triggering the camera yet. Since it will be, relatively speaking, a time exposure,  with a strobe sequence occurring somewhere in the middle, it isn't critical.

More critical is firing the bow and the strobe together. I may just make something like a fixed crossbow stock that accepts different sized bows, and has a trigger for both arrow release and the strobe trigger.

Since the Arduino program and some simple controls will determine the number, frequency and duration of pulses, that should be straightforward, once triggered.

I worried about how to contain all this in a dark enclosure, but duhhhhhhhhh, just remembered we have this thing here in Vermont called "night"!    :doh:   So I can just do it outside with my present target setup.

My camera happens to be pretty good with low light -- a Fuji Finepix with up to ASA 3200 capability, and a night time fireworks setting -- which is just about ideal for a multiflash strobe shot, I believe.

I dunno.......this might actually work......... :smart:

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