Here is the MagnumStar as finished.
Duplicate copies to ME and aditnow.
HEADSET
This has 5 X Cree Q5 emitters. The one that is in use most as a single lamp for normal use is driven at a comfortable 980 mA, the other 4 are in 2 series arrays and are overdriven at about 1060 mA each to give a maximum calculated light output of 1190 lumens
First switch position operates the single emitter by a lens that gives slightly more spill than the other 4, and has the usual low, medium and full mode settings plus stobe and SOS.
Switch position 2 will by flicking it on and off gives a range of ‘power’ settings.
All 5 on full
4 on full and one on half power
2 on full and one on low power.
You also get the strobe and SOS that comes with the drivers on just 2 of the other emitters; however there is a use to this as it indicates where you are on the mode range, full power is always after the slow on and off.
The lamp has 3 totally independent lighting circuits from 2 switch positions.
The weight of the headset is about 400 grams which is double that of the standard unmodified Oldham; however it is not really noticeable, at least not to me.
The power beam is a definite beam and has enormous throw, but also a reasonable amount of spill.
I have tested the lamp and its output is sustainable, after about 5 minutes large amounts of heat are being pumped out by the thermal conductor.
The front extension is made up from high pressure PVC pipe couplings designed for operation up to 15 psi. The original Oldham bezel is solvent welded to the extension, and the hexagon nut is likewise solvent welded to the headset. The only entry is by the high pressure joint which is sealed with silicone. The seal can be broken but takes some force, it then being necessary to clean away the old silicone and make a new seal. The thermal conductor is 12mm diameter and passes down inside the lamp for a distance of 20mm where there is a flat machined into it where the LED module is firmly seated with a 4mm screw. The thermal unit is secured by a nut and silicone waterproof seal.
BATTERY
The battery is made from a recycled Oldham MF battery case, cut down to about 40% of its original height and the bottom closed by a solvent welded piece of the same blue PVC material. It delivers 12.5 ampere hours at a nominal voltage of 7.4 volts (8.4 volts off the charger), and is made up of 10 18650 Lithium Ion cells in 2 parallel arrays connected together in series by way of a self resetting fuse. The cells are solidly potted in silicone, the whole being both waterproof and shock proof.
There is a digital battery voltage meter in the lid that gives readings for each parallel array and then the total voltage, typical example; No 1, 3.94, No2, 3.97, ALL, 7.91 in 6 separate short duration displays. It draws 0.23 watts at a current that varies with the state of the battery, average being about 0.02 amps. This actuated by a non rusting button on the end.
The meter is LCD illuminated display and shows accurate voltage to 2 decimal. I feel that this far superior to led displays as used by other manufacturers. It’s especially useful after taking off charge to ensure everything has done what it’s supposed to.
In the picture can be seen a brass screw protruding from the lid. This is the connection for a charging balance lead, in conjunction with through the headset clip. The charging is each parallel array alternatively with each being measured and charge disconnected when the appropriate voltage is reached.
The battery is slightly less than half the height of the standard Oldham and weighs just less than 1000 grams including the lid; the standard Oldham weighs more than double that.
I appreciate that some battery lid accessories such as the voltmeter or switch may become unserviceable in time, they are however very easily replaced and do not affect the performance of the lamp.
The only nuisance with the battery is that the belt mounts are not large enough to take a Caving Supplies belay belt which is my preference.
Looking at the specification, it can be appreciated that the main emitter in its full power setting giving more than 220 lumens would burn for more than 24 hours. The usual ‘walk mode’ as I call it for a Cree Q5 based lamp is the single emitter on medium setting which drives it at about 70%. On this setting the lamp would burn for about 32 hours.
My experience with the other lamps has shown that total amount of time spent on full power is a mere fraction of the total time spent underground on any one trip, with the time spent on the medium setting part way balancing the time spent on full power. The implications of this are that this lamp would probably last you for a week’s holiday away from charging facilities.
Its actually a lot more efficient on full power than I have posted before, its 20.88 watts out against 23.1 in. The lamps that I have built so far are very efficient; I think that this may be down to my matching the battery voltage to the design of my emitter circuit in the headset.
Final word about the battery, if the lid wiring was ‘crossed’ to put all in parallel it would deliver average of 4 volts and run a standard bulb Oldham for 24 hours with a half the weight to carry.
I expect that it will be some time before I start construction any to sell, I want to do a lot of kicking it about first. I expect that the price of these lamps will be no more than £200 however.
I set out to build a super lamp, and that is what I will deliver.
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My avatar is a poor likeness.