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CREG Journal
Contents

Newssheet (3)
Time for a Change, LORAN, Your Name in Lights, Diary Dates, CavingDiaries, International Speleo Congress.

3W Luxeon Caplamp with Microprocessor Control (4-5)
Martin Melzer describes his 'Radon' caplamp, which uses a PIC microcontroller to control a high-efficiency step-down switching regulator. As well as designing the electronics, Martin has produced a specially-machined rugged waterproof aluminum housing.

Satellite Images: A Buyer's Guide (6-8)
Mike Bedford gives a run-down of the satellite imaging products currently on the market. For the more technically minded some behind-the-scenes information on the technology of satellite imaging is provided.

Introducing Galileo (8)
Mike Bedford sheds some light on Europe's answer to GPS.

Operating a Solar Panel at Maximum Power Efficiency (9-13)
Solar panels have an optimum operating point that depends on illumination. David Gibson describes how, in a battery charger application, we can find this operating point and use it to make a more efficient charger.

A Simple Lithium-Ion Battery Charger (14)
Lithium-Ion batteries possess a high energy density but the charging requirements are exacting if damage is to be avoided. Ed Phillips presents a cheap and effective design that regulates charging voltage and limits charging current.

Speleonics (15)
The pros and cons of voice-based cave radio systems as compared with other methods such as textual communications. John Rabson summarises.

Low-Cost Implementation of a Speech Compression System (16-18)
David Gibson reports a method first described over 30 years ago, for compressing the dynamic range of analogue speech waveforms without increasing the distortion. A modern implementation uses simple software and a low-cost RISC micro-controller. The technique claims to increase the intelligibility of speech, which is a point to be investigated.

Caving with the Radon Caplamp (18)
Peter Ludwig has been using Martin Melzer's Radon caving light and reports on his experiences.

The Spring 2005 Field Meeting - Derbyshire (19-20)
For the Spring 2005 field meeting we visited historic mines in Derbyshire. Ian Cooper describes the weekend.

Updates: Li-ion Batteries; Radio-Location Beacons (20)
Martin Melzer follows up his article in CREGJ 59 and Brian Pease describes a modification to his beacon transmitter design.

A Flashgun Isolator (21)
Digital cameras can be damaged by connecting them to a traditional design of electronic flashgun. David Gibson describe an isolator that will protect the camera's sensitive electronics from the possible high voltage of a flashgun.

Web Watch (22)
Information on the Web, courtesy of Peter Ludwig, covering batteries, lighting and related issues. Online access to the sites mentioned is available from a page kindly provided by Martin Melzer.

LT-Spice (22)
Brian Pease describes a free version of the Spice circuit simulation package.

Radio Tests in a Hydro Power Station Feed Tunnel (23-24)
When drained for inspection, the range of VHF hand-held radios in the 3.7km Fasnakyle hydroelectric tunnel is severely limited. Rob Gill reports on tests at frequencies from LF to UHF, aimed at identifying a solution.

We Hear (25-26)
A round-up of news from the world of cave-related radio and electronics. Column edited by Mike Bedford.

Update: Flashgun Slave Unit for Digital Camera (26)
By David Gibson.

Letters to the Editor (27-28)
Letters.