This file is not intended to be read by humans. Please go to the formatted index

# format auto-updated on access: Mon 27-Nov-2017 11:29:02 +01:00

CREG Journal 78 (0-24)
This issue has a cover date of June 2012, but was actually published on 8 November 2012.

Front Cover (1)
Multiple exposure image created in a stone mine using the water cooled LED light described in this issue. Photo: Andy Lillington

Contents (2)
List of Contents and masthead information

Newssheet (3)
CREG Subscriptions, Diary Dates.

We Hear (4)
News and events - Mike Bedford brings us the latest to impact the world of cave radio and electronics. The Ultimate Cave Navigator?, Cave Detection NASA Style, PLBs Legal on Land, Free Energy from Viruses.

A Call Button for the Lovell Earth Return Telephone (5)
The Single Wire Telephone designed by Nigel Lovell works well but lacks a call facility. Chris Ross describes a simple modification to introduce a button allowing the user to be alerted to an incoming call.

Why Earth Resistivity Surveying Doesn't Work (6-9)
Following his introduction to the technique in the previous issue, Mike Bedford discusses some of the weaknesses of earth resistivity surveying. This is followed up with some practical suggestions as to how it could be made more effective at finding unknown caves.

Cave Radio Trials at Higher Frequencies (10-12)
Cave radio systems generally employ low radio frequencies. Rob Gill decided to examine the characteristics of higher frequencies in the cave environment, initially using readily available amateur radio equipment, to determine if practical applications for these frequencies may become apparent.

Letters to the Editor (13, 24)
QR Codes, Cave Photography, Cave Detection, Avalanche Transceivers

A Water-Cooled LED Light (14-18)
Andy Lillington has been building video lights for underground work for a number of years and describes the assembly of his latest compact water cooled design which, as a by-product, also provides for a pleasant hot drink afterwards.

Protection Circuit for a LiFePO4 Battery Pack (19-21)
Lithium Iron Phosphate cells offer high power density and long life but require protection from deep discharge. Adam Pyka offers a design for 12V Bosch power tools that is both cheaper and lighter than the manufacturer's own power pack.

Web Watch (21)
Peter Ludwig takes another look around the web and comes up with yet another selection of interesting links

Signal-to-Noise Ratio and its Assessment (22-23)
In traditional cave radio systems, the signal-to-noise ratio (SNR) of a received signal has rarely been estimated. Andy Talbot has made some software available for producing signals with known SNR, which can be used as an aid to assessing system designs. John Rabson reviews it.

The Adventures of GREG (24)
Illustrations by Adrian Higgins with words by Mike Bedford.