Silicon ChipGeocaching: Treasure Hunting With A GPS - August 2001 SILICON CHIP
  1. Outer Front Cover
  2. Contents
  3. Publisher's Letter: Knowledge nation is a woolly headed wish list
  4. Feature: Geocaching: Treasure Hunting With A GPS by Ross Tester
  5. Project: A Direct Injection Box For Musicians by John Clarke
  6. Feature: A PC To Die For; Pt.3 - You Can Build It Yourself by Greg Swain
  7. Feature: Help Reform Electrical Legislation by Silicon Chip
  8. Project: Build A 200W Mosfet Amplifier Module by Leo Simpson
  9. Feature: The Role Of Electronics In Mine Clearing by Bob Young
  10. Feature: Using Linux To Share An Internet Connection; Pt.3 by Greg Swain
  11. Project: Headlight Reminder For Cars by John Clarke
  12. Project: 40MHz 6-Digit Frequency Counter Module by David L Jones
  13. Order Form
  14. Product Showcase
  15. Weblink
  16. Feature: Uniden Mini UHF Two-Way Radio Competition Winners by Ross Tester
  17. Vintage Radio: Substituting for valves that are no longer available by Rodney Champness
  18. Book Store
  19. Back Issues
  20. Notes & Errata
  21. Market Centre
  22. Advertising Index
  23. Outer Back Cover

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Items relevant to "A Direct Injection Box For Musicians":
  • Direct Injection Box PCB pattern (PDF download) [01108011] (Free)
  • Panel artwork for the Direct Injection Box (PDF download) (Free)
Articles in this series:
  • A PC To Die For - And You Can Build It For Yourself (June 2001)
  • A PC To Die For - And You Can Build It For Yourself (June 2001)
  • A PC To Die For; Pt.2 - You Can Build It Yourself (July 2001)
  • A PC To Die For; Pt.2 - You Can Build It Yourself (July 2001)
  • A PC To Die For; Pt.3 - You Can Build It Yourself (August 2001)
  • A PC To Die For; Pt.3 - You Can Build It Yourself (August 2001)
Items relevant to "Using Linux To Share An Internet Connection; Pt.3":
  • Linux script files for Internet Connection Sharing (Software, Free)
Articles in this series:
  • Using Linux To Share An Internet Connection; Pt.1 (May 2001)
  • Using Linux To Share An Internet Connection; Pt.1 (May 2001)
  • Using Linux To Share An Internet Connection; Pt.2 (June 2001)
  • Using Linux To Share An Internet Connection; Pt.2 (June 2001)
  • Using Linux To Share An Internet Connection; Pt.3 (August 2001)
  • Using Linux To Share An Internet Connection; Pt.3 (August 2001)
  • Using Linux To Share An Internet Connection; Pt.4 (September 2001)
  • Using Linux To Share An Internet Connection; Pt.4 (September 2001)
Items relevant to "Headlight Reminder For Cars":
  • Headlight Reminder PCB pattern (PDF download) [05108011] (Free)
  • Panel artwork for the Headlight Reminder (PDF download) (Free)
Items relevant to "40MHz 6-Digit Frequency Counter Module":
  • 40MHz 6-Digit Frequency Counter PCB patterns (PDF download) [04108011/2] (Free)

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GEOCACHING:: Treasure Hunting For Techies With A GPS By Ross Tester Did you enjoy treasure hunts when you were a kid? Now you can re-live your childhood in a whole new, high-tech way with the world’s latest game/ hobby/past-time. All you need is a GPS receiver! S omewhere in the picture above is hidden a GPS stash, or cache. What, you can't find it? You need to get into the latest “game” on the planet, Geocaching. Geocaching (pronounced jee-ohcashing) is very new – so new, in fact, it won’t have found its way into dictionaries. It’s also so new that a lot of people don’t even know what it is, hence this article! First and foremost, Geocaching is a treasure hunt. But it’s much more – and much less – than that! Normally in a treasure hunt you 4  Silicon Chip expect to find, well, treasure of some sort. When you find the “treasure” in a Geocache cache you’re more likely to find a few trinkets which are worth next-to-nothing. And what’s more, you’re expected to leave something in return! Sometimes, though, Geocaching can be much more financially rewarding. Despite its youth, Geocaching contests have started to spring up with the winners taking home real dollars – $US5000 is not uncommon. But as we said, it’s much more than a treasure hunt. It’s actually closer to the “fox hunts” which amateur radio operators used to (and occasionally still do) take part in, where they are looking for a well-hidden transmitter with the aid of direction-finding receivers. (Please, no correspondence from irate amateurs telling us foxhunts are alive and well. I are one – amateur that is, not irate. But an amateur radio foxhunt may typically attract ten, perhaps twenty or so enthusiasts. A Geocache hunt may attract thousands of enthusiasts). With Geocaching, you’re looking www.siliconchip.com.au (Left): a typical cache, just before it is hidden. The case is waterproof, it is identified with the person or group who left it and it’s not so big that it cannot be hidden fairly easily. (Below): the contents of that same cache. First to find it would almost certainly claim the piggy and possibly polish off a Freddo frog or two. Actually, this one is a bit naughty because food in caches is not recommended – especially if the area is accessible to wild animals. for a (usually) well-hidden cache with the aid of a GPS receiver and a few clues. It’s sort of a cross between orienteering, treasure hunting, bush-walking, four-wheel-driving, occasional cross-country skiing, perhaps abseiling or rock-climbing, often a lot of undeleted expletives (depending on the company!) and much frustration. Sometimes the cache is not well hidden at all. It’s just there – beyond reach. Up a sheer pole or limbless tree. Down a cliff. A few fathoms under water. And so on. Part of the game is solving the problem of how to get there! The most annoying – and at the same time attractive – feature of a cache is that you could be quite literally standing on it without realising it. Something you’ve spent hours, even days, looking for might be unearthed by someone else, seconds after they get there! It’s one thing to know a cache’s location. It’s another thing completely to know exactly where the cache IS and lay your hands on it! What’s in a cache? About the only thing that’s found in just about all caches is a notebook and a pencil to record the successful finders. As far as the other contents of the cache, almost anything goes. No, that’s not strictly true – the contents are deliberately made to be fairly worthless to discourage looting. But looting and trashing of caches still happens occasionally. (That’s yet another reason why such trouble is taken to conceal, or at least camouflage, a cache). Food is not encouraged because wild animals have much better noses than we humans and have been known www.siliconchip.com.au to destroy a cache to get at the muesli bars or chocolates inside. So what goes into the cache? How about a Barry Manilow CD or cassette (yeah, we know, they’re pretty worthless). Maybe a couple of small toys. A comic book. Some really useful computer parts (memory chips for 8086 machines, perhaps?). Maybe the contents will reflect another of the cacher’s hobbies. Or if they want to convert the world, a Gideon’s Bible. As you can see, there is very little that can’t go into a cache. About the only no-nos are weapons of any kind (including ammunition) and drugs (although a couple of Winfields and a lighter wrapped in foil might save a desperate’s life out in the sticks!). The rules for Geocaching are very simple. When you have found a cache; 1. Note your find in the logbook 2. Take something from the cache 2. Leave something in the cache Most Geocachers are also conservationists. The old adage “take nothing but photos, leave nothing but footprints” almost applies (apart from what you actually exchange). But just as importantly, most Geocachers also take the opportunity to help mother nature out by taking rubbish out with them when they leave. How did it start? Geocaching only became possible on May 1st, 2000, when US President Clinton made the decision to remove the deliberate degradation of signals (called Selective Availability) from the 24-satellite Global Positioning System (GPS). This changed the accuracy of non-military GPS units from within about 30 metres or so to at least 10 metres – and often better. So now when you obtain a “fix” from a hand-held GPS unit (especially one averaged over, say, an hour or so) you can be pretty sure you can find your way back to that exact spot (or at least within a few metres of it). In celebration of the lifting of selective availablility, a chap called Dave Ulmer hid a container of goodies (actually an upside-down bucket) outside Portland, Oregon, USA on May 3. Its GPS co-ordinates were logged on the sci.geo.satellite-nav newsgroup and, by May 6, two people had found the “GPS Stash Hunt” container, as it was first called, and logged it in the book. Mike Teague was one of the two and he started building a web site at www. triax.com/yngwie/gps.html dedicated to this new hobby. In July 2000, Jeremy Irish found Mike Teague’s web site and found his first cache outside of Seattle, Washington. Recognising the potential of the game (but never expecting the growth), Jeremy approached Mike Teague with a new site design, used August 2001  5 Now that’s a bit unusual, isn’t it? A duck sitting up a tree? Yep, you guessed it – it’s a cleverly disguised cache, high enough to dissuade all but the most determined looter (or a determined Geocacher . . .) Here’s one of a Geocacher’s favourite hidey-holes: a hole in a tree-trunk. Just be careful it isn’t occupied by spiders, snakes or other creatures! Inset is the type of cache you’d find in such a place – in this case there is no need for camouflage colours because it’s well hidden from view, even from someone standing right there. But it’s no match for an experienced Geocacher, because he/she knows that’s just the sort of place to look! the name Geocaching, and developed a new web site – www.geocaching. com – adding virtual logs, maps, and a way to make it easier to maintain caches as the sport grows. www.geocaching.com is also the international “repository” of Geo-caches – at the time of writing there were somewhere around 3000 active caches around 50 countries including Australia. In the week before, an amazing 1797 logs had been written by 830 account holders with www.geocaching.com Geocaching is arguably one of the world’s fastest-growing pastimes. All you need to participate is a hand-held GPS unit (around $250 up) and some good bushwalking boots! OK, so some caches require a little more equipment – such as abseiling gear, a boat, a 4WD, perhaps even scuba gear! But equally, there are many caches which require only the basic equipment and some clear, problem-solving thinking. No fancy stories, or smelly locations. No trudging for hours through thick scrubby undergrowth. Just a plain and simple cache to get Geomon-keys on the board. Location is accessible via road, and public transport. Tracks can be water logged, so be prepared to splash a little, after rain. And come prepared for a brisk walk. There are three accesses, any one will do, and you’ll find our barrel south of the junction of the three paths. Have fun finding it, re-hide the cache carefully as eyes are all around.” One other vital piece of information is given about the cache: it’s grade. This is a measure of the difficulty of finding the cache and the difficulty of Gradings Take this one, for example – it’s a current cache hidden somewhere near Sydney: “Location: S33°48.543 E151°10.963 A suburban bush track that not many folks know of, but is rather attractive and interesting. 6  Silicon Chip Another variation on the hole-intree cache: a hollow stump, with just enough old timber piled on top to make it look “natural”. the terrain which has to be traversed, both on a scale of one to five. The above is rated 1/1.5 – almost as easy as it gets. Difficulty: 1 A ten year old could probably figure it out without too much difficulty 2 An average adult would be able to find this in about 30 minutes of hunting 3 An experienced Geocacher will find this challenging, and it will take up a good portion of an afternoon. 4 An extreme challenge for the experienced Geocacher – may require in-depth preparation or cartography/ navigational skills. 5 Mensa or equivalent T­errain: 1 Handicapped accessible 2 Suitable for small children; generally on trail 3 Off trail; requires some risk of getting scratched, wet, or winded 4 Off trail; likelihood of getting scratched, wet and winded. Probably requires special equipment (boat, 4WD, etc.) 5 Requires specialized equipment and knowledge/experience (rock climbing, SCUBA, etc.) An example of the “more difficult” caches? This next one is rated as 5/5 (as hard as it gets) and is located at S www.siliconchip.com.au 33°40.59 E 150°14.57 which puts it near Blackheath in the Blue Mountains, west of Sydney. Then again, you don’t have to be Einstein to work that out because the cache owners tell you that much in the clue. When you read the rest of the clue you’ll start to understand why it is rated 5/5 and also that some Geo-cachers take it all very, very seriously. “The cache is located near Blackheath in the Blue Mountains. The co-ordinates given are the exact location of the cache, but you will find it requires Abseiling/Rock climbing equipment for a 30 metre descent. The Stash is sitting, sheltered and comfortable, somewhere inside an old car that has been pushed to its death and rests on a narrow rock ledge. The ledge is still high above the valley floor so it is not safely accessible by any other means. A rather interesting and challenging place you will agree. In the cache, amongst other things, you will find some energy bars which you may need for the difficult ascent back out. Also the first finder will find some cash to help pay for your petrol or gear hire. This should be an exciting find but don’t attempt it without the proper skills. I have rated the overall difficulty as 5 even though it is easy to find once you get there.” Woh! I think I’ll leave that one to the seriously fit, expert Geocachers, thank you! Just to reiterate, all you really need is a GPS receiver and of course web access, so you can see where the latest (or in fact any) caches are close to you. And they are all over Australia and New Zealand now – you shouldn’t have to travel too far to get to a cache site. The www.geocaching.com site even makes life real easy by allowing you to search by country and even by keywords. It’s worth having a look at, just to see the trouble some people go to hide their caches. Searching for a cache www.geocaching.com has some pretty good tips for beginners. We’ll paraphrase these but if you’re serious, it will pay you to look at the site (you’ll Here’s a listing of Australian caches from www.geocaching.com As you can see, these are only the first 25 of the 96 sites listed in late June. You can bet there are even more now! www.siliconchip.com.au August 2001  7 Sometimes the cache hiders make it nice and simple for you to get to the location, providing maps and routes as part of the clue. Don’t expect finding the cache itself to be quite so simple! need to anyway to find the cache co-ordinates). 1: Research the cache – if you don’t know the area, buy a good map (preferably a topographical map) of the area. Navigating by GPS alone is not recommended, especially for your first cache hunt or if you don’t know the area. 2: Prepare properly. Have the right clothing (including boots) for the terrain and season. Always go with at least one other person and remember to tell someone where you are going and when you’ll be back. 3: When hunting the cache, use your GPS to enter waypoints (including where you left your car!). It’s easy to get within a few tens of metres; the last bit is the hardest. Try to think like the person who hid the cache: “where can I hide this so that noone will easily stumble across it”, and so forth. 4: When you’ve found the cache and noted your find in the book, take something and leave something, then make sure you seal the cache back up again and hide it exactly as you found it. 5: Afterwards: email the person who hid the cache to let them know you found it; go to geocaching.com and log the details there as well. 6: Sit back and congratulate yourself! Hiding a cache So you’d like to hide a cache, would you? Probably your best bet would be to first hunt for a few caches so you get to understand the ground rules. The cache container is all-important because it has to protect the cache 8  Silicon Chip contents from the weather (remember, the vast majority of caches are out in the open). Some people use buckets, others ammo boxes, others Tupperware or similar containers. Whatever you use it needs to be fairly neutral in colour or of a colour which will blend with the surroundings. If it’s easily spotted, it is likely to be raided. You’ll see all these things types of containers – and more – as you look for a few caches. You’ll also find what other people leave in their caches and some of the traps for young players. We’ve already mentioned food items. And we also mentioned a notepad and pencil. Why not a pen? If you leave your cache in country where it snows or frosts in winter, the odds are the pen will freeze up and become useless. Similarly, there’s not a great deal of point putting a notepad in an underwater cache, is there! (Some Geo-cachers have even used waterproof diver’s slates). You must be careful not only where you hide your cache but who owns the property it’s hidden on. Always ask permission from private property owners. If they allow people to bushwalk or hike through their property, the chances are they will be amenable to a cache. But you’re probably going to have to explain all about geocaching first! If it’s public land (eg, a National Park etc) then different rules apply. Beaureaucrats being what they are, the answer will always be “no” (unless you happen to strike a Geocacher!). We didn’t say this, of course, but sometimes its best not to ask! If you hide your cache well enough, it’s not going to be spotted anyway so “out of sight is out of mind”. And when you hide your first cache, you probably want the world to know about it. You can register your cache on www.geocaching.com – needless to say, you’ll have to give the GPS co-ordinates available and also a brief description of how to find it, without giving too much away! After all, there’s not much point in telling someone exactly where it is – that takes all the fun out of the game. Finally, remember that as the owner of the cache, you’re also responsible for it. You’re responsible if it causes damage or injury (that’s why you have to be careful about what’s in it). And if you remove your cache, don’t forget to tell www.geocaching.com so there aren’t millions of people (OK, thousands) trying to find a non-existent SC cache! Yet another variation on the hole-in-the-tree theme, although this one is a bit too obvious unless it’s deep in a forest, possibly with a lot of other obstacles (rivers, cliffs, etc) making access difficult. After all, no-one wants a cache that’s too easy. Incidentally, can you spot the cache inside the trunk? It is there! www.siliconchip.com.au