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# format auto-updated on access: Tue 01-Sep-2020 18:40:47 +01:00 CREG Journal 111 (0-28) This issue has a cover date of September 2020 and was published on 1 September 2020. Front Cover (1) While ascending 12 metres in a CaveSim system at CityROCK Climbing Gym, a schoolboy waves through a Plexiglass window from the vertical cave into a viewing area. Photo: Contents (2) List of contents and masthead information. News and Notes (2) Virtual Conventions, Internet in a Big Box (3-4) Jangala, a charity, has developed an innovative approach for providing Internet access in developing countries and during humanitarian emergencies. reviews this 4G-based package and considers possible cave-related applications. Modelling Microwave Propagation along Passages using LiDAR and Ray Tracing (5-7) describes how the availability of accurate 3D cave models, achievable using handheld laser scanners, has allowed propagation along irregular cave passages to be more accurately modelled using ray tracing. Photo Stacking in Cave Photography (8-9) considers a different approach for cave photography. This post-processing workflow shifts the most time-consuming parts of the creative process from the cave into your warm apartment. The Parallel-Fed Voltage Multiplier(10-12,22) Voltage doublers and the Cockcroft-Walton voltage multiplier are examples of devices that use capacitors as charge-pumps to generate a high voltage at a low power in a relatively simple circuit. The conventional voltage multiplier is series-fed, acting as a 'bucket brigade' to pass the charge from one element to the next. This is difficult to analyse, as well as being inefficient, with a law of diminishing returns applying. A better scheme is the less well-known parallel-fed device, which has several advantages. analyses this device, arguing that it deserves to be better known, and suggests some possible cave electronics applications. We Hear (13) Roundup of news and events: brings us the latest to impact the world of cave radio and electronics. Pull Chord Light and Power, Cross-band Repeater Controller, WaterLily Gets an Upgrade. Micropower Lesser Horseshoe Bat Sensor (14-19) A new design for a low-power bat sensor has been deployed at five major regional cave sites for the winter months of early 2020. presents data logger results showing similar timings across all these caves suggesting that hibernating bats are roused by common factors such as external weather patterns and then influenced by such thereafter. Relatively low counts at one entrance suggests that its substantial locked gate is impacting bat access to potential habitat within. Web Watch (19) Lots of links this time, from batteries to power tools and satellites to thermal imaging, from . The Mystery of the Missing Energy (20-22) Whenever a capacitor is charged, energy seems to go missing. This has consequences when designing equipment that makes use of capacitor charging, such as a charge pump. explains the phenomenon and challenges the reader to say where the supposedly missing energy might have gone. The Ongoing Story of CaveSim: the Artificial Techno-cave for Training and Education (23-24) brings us up to date on the CaveSim educational facility by describing recent software improvements and other key developments. Building Blocks (25) The 'bargraph' display - applications and circuitry by . Earth Resistivity Surveying: a New Approach (26-28) presents a novel intelligent electrode, as a top-level design, aimed at making earth resistivity surveying an easier to use method of cave detection. [diagram on p28 revised 17 Nov 2020].