Recently I started reading more here again (mainly HID section) and I thought I'd have a share in here
by introducing me and my spotlight dependence with this report about another home made HID.
Some time ago, by pure coincidence I got hands at
- a 120W UHP bulb
- including the invaluable ballast (Osram)
And in connection with
- a modified 24-30V/230V stepup converter, to provide the required 300V for the ballast
- two 4S 14.8V 5Ah LiPos in series
- volt warners
- and a bunch of parts within reach for the chassis, the most prominent being
- a nice green pvc sewer tube!
...I could start all this.
Just to have an immediate full stop.
because the step up converter doesn't accept more than 30V and the two LiPos had slightly more.
I already had a 4S battery for another lamp, that's why I bought a second one (to save money. ha! what a silly idea...)
So I purchased a 2S 5Ah from Hongkong to get a 6S chain in series, and then, holy gee!, the german customs confiscated it
(because meanwhile there's a horribly nasty import issue about a required "CE" sign, and the customs believing it)
Thus I had to purchase another battery from an inner-EU country.
Now I could do a first unassembled test run which looked fine!
(cell phone picture)
Next I had to assemble all the stuff,
...did various silly things for several hours, and eventually got this far,
with the front looking like this (get anything which remotely works, but just get it),
simply having scissored a metal sheet with the grinder, with the bulb being fixed into with epoxy glue.
Ok, now it was portable.
So what do beam shots look like?
I compared it with a Vector PowerOnBoard (SLH100P) (I'm so glad that one went astray to germany on ebay)
and an EagleTac M3C4 single XML-L,
Here's the long shot, looking along the Donau (danube river) in Ulm, southern germany, where I am located by the way,
The distance to the higher white building in the background is about 635m/2080' (according to google earth)
and the stone column below (located on an isle in the river and illuminated by default) about 315m/1030'.
I couldn't see the EagleTac on the building anymore, so here's the far distance without it
(ISO 100, 2 sec, F5.2, 23.7mm, earlier sony cybershot)
635m -- control shot | POB 35W | home-made 120W UHP
and here, targeting the column, 315m -- EagleTac XM-L | POB 35W | home-made 120W UHP
I'd say I'm more than happy with the result!
Not until later, when puzzling with the pics, I noticed three guys sitting in the front of the stone column!
and these guys had visited me not much later after this shot. We had a nice talk,
the first word was "bazooka!" (not sure if that was meant as praise or blame),
and then the usual questions from people which until then had not known that flashaholics exist,
"whatcha doing with that?!", well nothing, but having lots of fun ;-)
Then they said "thought it was just a flash light" and I was tempted to be in a snit,
but on the other hand they had walked back the isle and then to me, which is more than 1km ;-)
Then they recommended to switch it off before police would arrive on site
but I replied that I'd only be afraid of that when fiddling with lasers...
We then inspected the buildings around, paying great attention not to flash any traffic or pedestrians,
and as police was not showing up anyway, we finally all went home.
Great. But soon I was annoyed by having to fiddle with two batteries (and thus two volt warners),
and the switch was a temporary solution, and the tube a bit shorter would be great,
and how nice the handle might be, I didn't love it!
I had misused a mortar (guess it's called like?),
So I purchased another LiPo, 6S 8Ah,
another charger, because I only had one for 4S batteries until then,
yet another nicer handle
a reasonable switch,
and eventually the little green hideous looked like this!
I admit, I do like warning signs, printed them myself and covered them with transparent tape,
and they're even not a lie, due to both high ignition and working voltage, hot surface, and great brigthness.
Ok, yes, I modified the laser symbol (horizontal line removed) because I like it more than the official brightness symbol.
Perhaps a few more words about the bulb,
. UHP (ultra high pressure), mercury vapour (instead of the automotive mercury metal halide type)
. electrode gap 1.0mm
. reflector about 60x53mm which corresponds to a circular shape of about 62mm diameter
. power 120W
. working voltage about 60V
. 7000 lm -> ~58lm/W
. light output typical (bundle lumen at 2.4m): 3200 lumen
. working pressure ~200bar
. colour temperature: CCT: 7600K, CRI: Ra 57
killer features of these bulbs are
- small electrode gap which allows for an astounding throw, given such a small reflector,
- and very high pressure, which means broader spectral lines, and more red light
which results in a nice neutral white despite the high color temperature
It's an an Osram ballast and originally I had started with an Osram bulb, too.
However, it was an elliptical type by accident and I ended up with a parabolic one from Philips.
Thanks to Ot10St! who is responsible that I was able try such a build at all.
Well, I'm so happy with the little green hideous
(but gee, would it be nice to have access to 300+W ballasts, too? ;-)