The Magic Dragon
I am now testing the first of the Dragon 1200s, "The Magic dragon", so christened because it really is magic.
An old say is that "There is never a second chance to make a first impression" , this is usually related to selling something but when once builds lamps the first impression is when one first try's out a new model underground.
I was at the NAMHO AGM on Saturday at Matlock and afterwards took the opportunity to try it it in Devonshire Cavern. Of all the lamps I have built to date this is the most impressive. I thought the other one was good but this one really does it. Its difficult to describe, but walk mode is a fairly overall even lighting effect and very crisp.
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I have built it around 4 X Cree XP-G2 S2 emitters, two in series behind reflectors, two in series mounted on the inside of each reflector just inside the rim. These are switched independently to rum on a single mode of 150 mA and produce just under 150 lumens as far as I can calculate. They also run in combination with the beams at 60mA.
It looks a lot more because most of the light is being directed down at the floor. Using them independently for bolting or similar just tilt the lamp upwards.
I consider foot level illumination very important with XP-Gs because the beams from these are very tight with an almost total cutoff.
The beams are at three modes. 170 mA is the standard or walk mode plus the floods on a low level to give a battery hit of about 210 mA, then there is a medium, and a maximum if 1.4 amps to the beams plus the same 60mA to the floods.
The maximum power I calculate at about 1175 lumens, and whats more initial testing indicates a heat sustainable output.
In use its impressive to say the least, it weighs nothing and does everything. I have designed a new 2 Series Li Ion power pack same size and weight as for the D800, standard mode should run for about 12 hours at which point the lamp will unfortunately suddenly die.
I am in truth niggled by the abysmal efficiency of the flood driver, but I am very limited by space. Upper half carries the toggle switch with the only room is on each side of it, lower half is filled by the main switch mode driver, inductor coil and all. To make matters worse a lot of the simple linear drivers have too high a minimum voltage being primarily designed for auto applications, this severely limits choice. But I bet Mike will come in with a "try this one Roy"
;D
The flood emitters are bare XP-Gs to which I solder anode and cathode wires plus a little bit of flat copper to the central heat pad. I then carefully face it down with a fine warding file before mounting it on a little heat transfer insulation pad on the inside of the reflector. Heat transfer I regard as dodgy but at a max of 150 mA is irrelevant, well fresh battery gives about 190 for what difference.
I wont be producing these to sell for a while as I need to test exhaustively due to breaking into new ground with this lamp. Up until now they have all followed tried and tested design.
My avatar is a poor likeness.