Steampowered Posted January 19, 2019 Share Posted January 19, 2019 Hi I have just read that fitting resistors and capasitors into the bus wire is a good safty feature. Can anyone help as to which ones are fitted and where in the bus wire are they fitted. Thanks Link to comment Share on other sites More sharing options...
John K Posted January 19, 2019 Share Posted January 19, 2019 (edited) What you are asking about are Bus Snubbers or Bus Terminators It gets discussed here fairly often and people argue interminably about their usefulness, with many quoting theoretical electronics and others quoting empirical experience. I am agnostic on the subject. http://www.rmweb.co.uk/community/index.php?/topic/56688-dcc-bus-terminators/ John K Edited January 19, 2019 by John K 1 Link to comment Share on other sites More sharing options...
Steampowered Posted January 19, 2019 Author Share Posted January 19, 2019 What you are asking about are Bus Snubbers or Bus Terminators It gets discussed here fairly often and people argue interminably about their usefulness, with many quoting theoretical electronics and others quoting empirical experience. I am agnostic on the subject. http://www.rmweb.co.uk/community/index.php?/topic/56688-dcc-bus-terminators/ John K Thanks John. Link to comment Share on other sites More sharing options...
Crewlisle Posted January 19, 2019 Share Posted January 19, 2019 What you are asking about are Bus Snubbers or Bus Terminators It gets discussed here fairly often and people argue interminably about their usefulness, with many quoting theoretical electronics and others quoting empirical experience. I am agnostic on the subject. http://www.rmweb.co.uk/community/index.php?/topic/56688-dcc-bus-terminators/ John K Why does everyone want to over complicate DCC & frighten off potential users? I converted my 45 year old layout Crewlisle to DCC 10 years ago, useing Lenz & the only things on my bus wire are the 4mm banana plugs which connect the bus wire across the baseboard joints. Over the last 10 years I have never had problems with any of my DCC hardware. Peter 2 Link to comment Share on other sites More sharing options...
Pete the Elaner Posted January 20, 2019 Share Posted January 20, 2019 Why does everyone want to over complicate DCC & frighten off potential users? I converted my 45 year old layout Crewlisle to DCC 10 years ago, useing Lenz & the only things on my bus wire are the 4mm banana plugs which connect the bus wire across the baseboard joints. What you can get away with is not always a good recommendation. Without discussions like this we don't learn from each other. Feel free to not implement them but please don't complain about them being discussed. 3 Link to comment Share on other sites More sharing options...
Alan Kettlewell Posted January 20, 2019 Share Posted January 20, 2019 Why does everyone want to over complicate DCC & frighten off potential users? I converted my 45 year old layout Crewlisle to DCC 10 years ago, useing Lenz & the only things on my bus wire are the 4mm banana plugs which connect the bus wire across the baseboard joints. Over the last 10 years I have never had problems with any of my DCC hardware. Peter I've experienced occasional problems with a loco chip not responding in one of my power districts. Fitting a snubber to the end of that bus spur resolved the problem. Cheers ... Alan 1 Link to comment Share on other sites More sharing options...
JST Posted January 20, 2019 Share Posted January 20, 2019 I've experienced occasional problems with a loco chip not responding in one of my power districts. Fitting a snubber to the end of that bus spur resolved the problem. Cheers ... Alan Yes..me too! 1 Link to comment Share on other sites More sharing options...
Phil S Posted January 20, 2019 Share Posted January 20, 2019 (edited) Discussions about adding 'snubbers' or 'filters' as a benefit or otherwise are meaningless without also specifying the other technical factors affecting the layout - such as the makeand model of controller, and the gauge, physical length and connection patter of any distribution busses, and what other devices are fitted to the layout. EG with my Zero-1 installation as I addesd the last few of 30 accessory decoders, I found I had to remove the capacitorseach had accross their inputs, and shorten my overall wiring length, to maintain the waveform shape ! I have posted in another thread, examples of the waveforms from 3 different, current, DCC controllers (2 makes) - showing very differing 'quality' outputs - and also how simply adding some loco decoders affected the output. The 'theory' behind adding terminators and snubbers is important in many circumstances - and across many cabled systems - from Disc Drive (SCSI) chains to coax - 50 or 75 ohm terminated control systems .... using the wrong terminator at the end of a branch causes reflections back along the cable which can create nulls where no useable signal is available ( I may even have this on one of my TV distribution paths at home ! - not helped my differing tranmission strengths and standards (Crystal Palace) - so that 'signal strength' is not an adequate measure on its own ... its too easy to clip the supposedly digital muti-level DVB signals !! - but DCC is only binary in level, thankfully (except when using assymetric braking/signalling/control. it is much the same as people discussing wiring - what works acceptably for a 1-2A controller becomes inadequate for a 3-5, or higher output. These details MUST be specified for the statement to be of relevence! The dcc signal is relatively immune to problems of reflection, and is desinged to work on long lengths. However, it can be affected by what else is attached - and where. And unlike a simple 'transmission line modelling' calculation for the national grid - the situation with a model railway is VARYING CONTINUALLY when any train is moving. Different makes of decoder also respond in differing ways. Edited January 20, 2019 by Phil S 1 Link to comment Share on other sites More sharing options...
Crewlisle Posted January 20, 2019 Share Posted January 20, 2019 You may have problems with sections that use current detection if you use an RC snubber in those sections,otherwise no. If you have twisted the cable pairs of your bus at least 4 turns to the foot your are unlikely to need them at all though, even with a bus beyond 30ft.However for a bus over 30 ft, voltage drop maybe an issue, dependent on starting voltage, number and type of joins and the guage of the wire used. Further to my Comment No. 4, I have just read the above comment by Kal on 'DCC Bus Terminators' on 1/6/12. Both my 5 amp bus wires & all my droppers are twisted together as originally recommended to me. Could that be one reason I have been 'lucky' with no hardware failures? Peter 1 Link to comment Share on other sites More sharing options...
Pete the Elaner Posted January 20, 2019 Share Posted January 20, 2019 Further to my Comment No. 4, I have just read the above comment by Kal on 'DCC Bus Terminators' on 1/6/12. Both my 5 amp bus wires & all my droppers are twisted together as originally recommended to me. Could that be one reason I have been 'lucky' with no hardware failures? No. Twisting wires together reduces crosstalk. Snubbers ease spikes due to short circuits. I have not suffered either, although my bus is sheathed mains cable, so that may well be twisted & with reference to the above post about different recommendations for different systems, maybe both you & I have command stations which effectively have integrated snubbers? If I do get strange issues, I will know some things to try. Link to comment Share on other sites More sharing options...
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