but basically this is a reverse build of my ring light since i didn't take that much notes when i built the damned thing.
well type:1 was 30 8000mcd 3mm white led's mounted on a clip made from polymorph
(fantasic stuff)
they were arranged in 10 sets of 3 in series with a forward voltage of 3.2 volts this made the it run at 9.6 volts and 20ma per string current would be 0.6 amps!!
so used a Duracell PP3 since they can supply that for short periods.
this was good but kept slipping off my lens (the clip was held tight with Velcro)
(un)fortunately there are no photos of it (to my shame i don't do nice work)
anyway type 2, purchased 100 white led's from a chap from china off ebay set me back about £8.00
while i waited for them to arrive (they took about 5 days) i had to figure out some way of attaching the damned thing to the camera, after trying to hook stuff on the tripod mount, rubber,sticky fixers,smeg and willpower my flatmate said about a filter holder that would hold such a device on.
off to a the camera shop i did go..
mr camera man was busy selling me a filter holder (£20 notes) when he said i needed an adaptor on seeing it i returned the filter holder and bought it alone (£11)
what i purchased was this
cokin p series filter adaptor for 52mm thread
an 84MM dia disc of alloy that fits secure to the front thread of my camera.
now being £11 i didnt want to do my standard bodge it till it works
so planned what i was going to do...
now the problem is that when this is fitted there is stuff behind the disc that could prevent correct operation of the camera. so with a tape measure i worked out that as long as there was nothing inside the 62mm dia all would be good so to some CAD i did go..
using Cadema free cad tasic :)
now that i had figured out what arrangement they should be, i now had to think how to power it,
A/resistors
B/constant current
c/switch mode supply
d/parallel
e/series
f/hook them all in parallel and smack a primary cell across it.
i opted for for option F, its not current/volt limited, not balanced etc but it was only ever designed to run for a short time and at 8p a diode i didn't care if i blew them all.
i drilled out the holes with a dremel clone, first .5mm then 3mm, if you look close you can see where i fucked up the drilling a few times :( (note to self must fix the robo driller) then with super glue put each one in place, inside ring first, glue-chop leads-bend-test-solder.
the inside ring is inverted electrically to the outside, this meant that between the two rings i wouldn't have to worry about shorts since it was anode to anode (why am i thinking of requiem for a dream?)
so once all that was done i wandered around trying to photo people after blinding them i realised that 100 diodes might have been a bit of overkill :)
now i have a light ring that's too bright to use, so i will have to come up with a dimmer circuit and put a diffuser in from (thanks to a suggestion from hackaday)
i ran it of 3 alkaline cells and took some measurements and wasn't very happy 3.6 volts 0.5 amps? so with all lamps running at 1/4 of there rated power?
in the spirit of tool time MORE POWER OOO OOO OOO.
3 x nickel metal hydride AA cells (somewhat known for there current capacity) and ...
2.5A at 3.6volts so each lamp is over driven by 5mA :)
now i have ring lamp that instead of blinding is too painful to be in the same room :D
so in the end as a ring light its shit, unless you want to burn out retina's
as a impromptu tony stark costume its ace, pop inside shirt turn on I AM IRON MAN...
it doesn't like running for long periods either but thats not what it was designed for.
the colour isn't that nice, its harsh and cold, but can be fixed in post or using white balance in the camera.
so just to give me something to do i am bulding mark 3, using the same filter adaptor but 70 RGB 5mm leds, colour selection by wii nunchuck :) watch this space
more pics when i learn that a glass of wine after dinner is good, a bottle is not
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