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Non-terminal snubbers
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I am building a layout with 4 Power Districts. Three PDs have the power supply located at their midpoint and have two track bus that are each less than 30 feet long. It would be helpful to have the fourth district have the power supply offset, producing a 20 foot bus and a 38 foot bus. All of the track bus will have terminal snubbers and twisted (3/foot) wires. Would it help to put a snubber midway on the 38 foot bus?
Thanks, Michael
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Michael, no it’s not needed.
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The purpose of the snubber is to reduce the reflected signal at the end of an unterminated buss; not needed in the center of a buss. Paul O
On Mar 12, 2020, at 9:17 AM, Michael Boyle <boyle10017@comcast.net> wrote:
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Carl
Hi Gang: How do
you know if you need snubbers? What do you see? Is there a
test? Carl.
On 3/12/2020 12:50 PM, Paul O wrote:
Michael, no it’s not needed. The purpose of the snubber is to reduce the reflected signal at the end of an unterminated buss; not needed in the center of a buss. Paul OOn Mar 12, 2020, at 9:17 AM, Michael Boyle <boyle10017@...> wrote: <snip> Would it help to put a snubber midway on the 38 foot bus?
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Robert J Miller CFA
Check the current flow near the end of each buss. I found a spike near the end of a roughly 45’ buss using my RRamp Meter. I installed an NCE snubber and it disappeared.
From: w4dccqa@groups.io <w4dccqa@groups.io> On Behalf Of
Carl
Sent: Thursday, March 12, 2020 2:39 PM To: w4dccqa@groups.io Subject: Re: [w4dccqa] Non-terminal snubbers
Hi Gang: How do you know if you need snubbers? What do you see? Is there a test? Carl. On 3/12/2020 12:50 PM, Paul O wrote: Michael, no it’s not needed.The purpose of the snubber is to reduce the reflected signal at the end of an unterminated buss; not needed in the center of a buss.Paul OOn Mar 12, 2020, at 9:17 AM, Michael Boyle <boyle10017@...> wrote:<snip>
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Carl, the symptoms you’ll see is erratic behavior of a loco (stopping, not responding to the throttle, etc.) on a certain part of the track, usually not far from the end of your bus wire. This one is kinda like the “if it ain’t broke, don’t fix it“ situation. Much more info here: Paul O
On Mar 12, 2020, at 2:38 PM, Carl <carl.blum@...> wrote:
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Rich Randall
You are really going to love it if you need snubbers and don't have them.
From my experience: locomotives jerking, stalling, ignoring commands, and loss of brains, and occasionally, burned out decoder.
The info on the web is plain: Buss runs of greater than 30 feet from the booster, with non-twisted wire.
https://sites.google.com/site/markgurries/home/dcc-general-best-practices/wiring-planing/snubbers-rc-filter
Rich Randall
Gettysburg, PA Modeling The Milwaukee Road at Avery, ID, in O Scale The BSME is now on facebook:
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