I have recently been playing around with a high performance slave flash unit which may be of interest to club members who like to take the odd snap down a hole. The unit has been designed by a member of the Cave Radio and Electronics group of the BCRA and seems to perform very well. The whole unit plus batteries will easily fit inside an empty clear film canister with just two external wires coming out to connect to the flash gun. There is no switch to get wet or muddy since the batteries are permanently wired and have a life of years due to the low power consumption of the unit. When attached to a flash gun the unit can be triggered by another flash at considerable distance. The designer claims it is sensitive to a flash being let off 1km away! This means it is sensitive enough to be triggered by flashes around corners and not directly in sight which is a great advantage in a cave. Also the unit is relatively insensitive to being triggered by cap lamps etc. and can be used in daylight (?).
Anyone interested in a unit can get a contact address from me. The units cost £25 ready made or £13 in kit form. In either case you will need some knowledge of electronic construction to get it up and working. For larger orders there are discounts (œ8 for kit) so it may be worth clubbing together if people would like any of these units.