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| VIDEO CLIP: Short-proofing your layout | ||
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   Registered Member #1 Joined: Sun Mar 12 2006, 11:44PM: posts: 34 | Here's one of the better previews from DVD volume 3 ... this shows how you can literally short-proof a DCC layout. Be patient ... it can take up to 60 seconds or more for this video to load on some connections.  Playing time: 2:18 To play this video in a resizeable desktop viewer, click here. NOTE: This will make the image larger, but it will not increase the image quality. [ Edited Mon Feb 02 2009, 07:02PM ] | ||
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| Joe Fugate |
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   Registered Member #3 Joined: Fri Sep 08 2006, 01:59PM: posts: 144 | FLASH! The latest insight on DCC short management with auto tail light bulbs ... If you use or have thought of using the 1156 bulbs for short management on your DCC layout, here's a great web link with lots of insightful details ... http://www.members.optusnet.com.au/nswmn/1156.htm#i1156test One of the handier things Marcus Ammann has on this web page is an in-depth study of amperage draw and the effect of the tail lights on voltage drop. Very cool and helpful. Marcus has done his homework, too. An 1156 bulb (27 watts) will limit current to 2.1 amps, while a two-filament 1157 bulb (33 watts - if the filaments are wired in parallel) will increase the current limit to 2.5 amps. Wiring two 1156 bulbs in parallel increases the current limit to a whopping 4.2 amps. This means using something like: 1. Two 1142 bulbs in parallel (18 watts) would give you a 3 amp current limit 2. Two 1152 bulbs in parallel (17 watts) would give you a 2.8 amp current limit Two 1142 bulbs in parallel would be just about perfect seems to me, allowing 3 amps to flow, which would not limit loco consists as much, yet keep the current low enough to not get bad damage from the short. Using two 1156 bulbs in parallel not only lets over 4 amps flow in the short, it may cause the booster short protection to trip. So working your way up the list you have: 1. One 1152 bulb - 1.4 amp limit 2. One 1142 bulb - 1.5 amp limit 3. One 1156 bulb - 2.1 amp limit 4. One 1157 bulb - 2.5 amp limit (if both filaments wired in parallel) 5. Two 1152 bulbs - 2.8 amp limit 6. Two 1142 bulbs - 3.0 amp limit 7. Two 1156 bulbs - 4.2 amp limit 8. Two 1157 bulbs - 5.0 amp limit (if both filaments wired in parallel) This allows you to tune your layout's amp draw and short flow limit to your liking. Going with 3 amps may be about right in HO, but going over 4 amps isn't a good idea since it would allow shorts to start doing some serious damage. [ Edited Thu Apr 10 2008, 11:39AM ] Joe Fugate http://siskiyou-railfan.net - 250,000 hits and counting!  | ||
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| Joe Fugate |
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| Registered Member #3 Joined: Fri Sep 08 2006, 01:59PM: posts: 144 | The other consideration is how many amps a short will draw from the other trains in that booster district. In other words, if you have a 5 amp booster district, and you are using train blocks with 1156 bulbs, then a short will consume 2.1 amps of the 5 amp booster capacity, leaving 2.9 amps for other trains in the booster district. Obviously, the higher you raise the short limit, the less of the booster capacity you will leave for other trains. So you may need to experiment with certain bulb combinations and the size of your booster districts (bigger district -- more trains may be in the district; smaller district -- fewer trains may be in the district) to get a good balance. One final note: avoid the temptation to go with 8 or 10 amp boosters unless you use something like the bulbs to limit the current to the track, since an unprotected short with a full 8 or 10 amps running through it can really do serious damage to small scale (HO or smaller) equipment. With a 10 amp booster and 14 volts output, you will be running the equivalent of a 140 watt resistance soldering iron through the short contact point. Meltdown time!  If you use the bulbs as explained above, you will limit the current to the track as described, thus saving your equipment! Not bad for about $2 per train block -- if you burn up that new BLI sound loco with a 10 amp short, you'll easily be out more than it would take to short protect a large club layout with the bulbs.  [ Edited Tue Sep 04 2007, 12:25AM ] Joe Fugate http://siskiyou-railfan.net - 250,000 hits and counting! | ||
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