Caving Lights
This is one of a pair of Oldham mining/ caving cap lamps given a
new lease of life. The lamp unit was bought for a few pounds from ebay, and
cleaned of loads of ingrained coal dust. The bezel was replaced with a new spare
from Caving Supplies in Buxton.
The original lead acid battery was dead and couldn't be revived so
I made a new battery box containing a 4.8V 3.3Ah NiMh battery pack, and a diode
to dring the voltage down to closer to the 4V that the lamp should run on. The
unit is not completely sealed, but could be if required- the box housing the
battery is a diecast one purchased from maplins. Thin foam is used in the lid to
stop the battery moving round. The gland is one i had removed from some scrap
piece of equipment, and the cable is a rubber covered type to give good
flexability. the Bracket is made from a scrap piece of stainless steel rescued
from a skip, and held on with some pop-rivets.
A cannon sure-seal connector is used to join the battery pack to
the lamp and to allow charging. I chose the sure seal as it is waterproof when
used with the right size of cable, is relatively cheap and robust. It is a push
fit connector, so will seperate without damage if the cable is badly
snagged.
Battery life is about 3hrs, so this light is only used for simple,
short dry mine exploring- I have superceeded it with a more modern LED light for day to day caving use.
Caving Photographic Light
This project was built to provide an even, bright waterproof
floodlight to use for cave photography. It had to be waterproof and robust to
suit being dragged through a cave, be bright as practical and give a good
colour rendering.
I based the project on a Underwater Kinetics dry box with a
clear lid. These are made of polycarbonate, so are very robust , and using one
to house my camera on multiple trips into various caves has proven out it’s
durability. The only foreseeable issue is that polycarbonate is not very
scratch resistant as proven out by the state of my Nalgene bottle over the past
few caving trips.
The main LED board was one of the Big Clive kits (see links
page). This meant I was able to have a robust board, of a size which fitted
neatly into the box (very handy) for a few pounds- no need to start from
scratch. The board was populated with 45 white superflux LEDs bought thorough
ebay, with a brightness of 3000mcd each, resulting in a 135000mcd total.
Choosing these does not make a super-bright lamp, but enables me to prove out
the concept cheaply, requires no further optics, and doesn’t need lots of
cooling. If all works out well, I will upgrade to brighter LEDs later.
On one side of the box is mounted an aluminium strip ¼”
thick, tapped to take a camera tripod mount, so the light can be set up on its
own. On the end of the box is mounted a waterproof toggle switch and cover. The
cover means that the light can’t be accidently turned on in the caving bag.
Where the switch and the bolts for the plate penetrate the case, I have used a
generous amount of silicone sealant to ensure a good seal.
The last major item is the battery- this is made up of 2 6V,
2600 mAh Nimh battery packs, bought from Modelpower. Although I could have used
a lower operating voltage and chosen the LED dropper resistors differently, I
wanted to be able to use the batteries elsewhere or for a future upgrade.
Modelpower sell all the connectors so I was able to make up a neat loom to
series the batteries together and to connect them through the switch and to the
board. Charging is relatively easy as the lid of the box can be opened and the
battery packs removed.
The batteries and main LED board are held in place with some
high density foam, shaped to fit suitably.
The light hasn’t yet been used in anger- this should be done
in the next couple of weeks, I will then post up some photos.