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CREG Journal
Contents

A Flood Early Warning System for Irish Caves
Adrian Thomas has been using data loggers to investigate the relationship between rainfall and flooding in caves. His aim is to provide an electronic noticeboard to provide early warning for cavers in some of Ireland's most popular caves. Here he describes progress so far and his future plans.

Wet & Dry
We review another Panasonic Toughbook and a new super-tough Aquapac, look at equipment labels which are suitable for the cave environment and consider pressure testing of enclosures. Column edited by Mike Bedford.

Web Watch
Peter Ludwig brings us a wide-ranging selection of sites.

Greater Efficiency with a New Radio-location Beacon
In order to provide greater range, Brian Pease has developed a more efficient higher powered beacon for use with his DQ Radio-location beacon. Here he describes the new circuit and provides construction details.

Cave Radio Notebook
57: Metal Sheets as an Alternative to Earth Spikes (John Rabson). 58: Calculations for Plate Electrodes (David Gibson). 59: Wenner Array Measurements (John Hey). 60: Wenner Array Underground (Rob Gill). 61: Using DTMF signalling with a HeyPhone (Rob Gill). 62: LORAN Spectrum Analysis (David Gibson). Column edited by David Gibson.

Investigating Ultra-violet Light Sources
Ultra-violet light is necessary for dye tracing; it's important too for those cavers and mine enthusiasts interested in mineralogy. Mike Bedford looks at UV light sources from the traditional mercury discharge lamp to the latest generation of UV LED. Background information on UV and fluorescence is provided.

Dolwyddelan, Llechwedd y Cwm Orthin - the Spring Field Meet
For the Spring Field Meet we visited slate mines in the Blaenau Ffestiniog area of North Wales. John Hey describes what went on.

Electronic Detection of Carbon Dioxide in Caves
Concerns have been expressed about the high levels of carbon dioxide found in some caves. A long-term study of CO2 levels would be an interesting project, but CO2 sensors are expensive. Here, David Gibson describes a possible method of constructing a cheap sensor that would be affordable by students and amateur scientists.

An Experimental HeyPhone on 38.4kHz
John Hey describes how to adapt a HeyPhone for use on 38.4kHz. Preliminary results on this new frequency are encouraging with interference much reduced compared to the usual 87kHz.

Frequency Synthesis - Some Possibilities
David Gibson discusses methods of adapting cave radios to work on different frequencies.

We Hear
A round-up of news from the world of cave-related radio and electronics. Column edited by Mike Bedford.

Tunnel Communications 1924 Style
A 60-year old photograph shows that experiments in tunnel communication have a long heritage.

Letters to the Editor
Waveguide Propagation in Railway Tunnels?, Data-Logging Update: Plug-in Memory Cubes, An Instrumented HeyPhone, Ultrasonic Microphones for Bat Detection.

Correction
to Wet & Dry (Sealant for Connectors by John Hey), CREGJ 55, p.25.