1. w4dccqa@groups.io
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Re: BD20

RONALD ST.LAURENT
 

Richard,

Have you checked all the track in the block to make sure it is isolated?  Sometimes cut track can rejoin.  A small piece of plastic placed in the joint and trimmed properly can be unobtrusive and keep the gap.

Ron

On Thursday, March 21, 2019, 8:17:32 AM EDT, Richard_vanRaay via Groups.Io <richard_vanraay@...> wrote:


Hi, thanks. I have 18 BD-20's connected to AIU's.
They have been working for about two months. Now one is showing occupancy all the time. The LED on the AIU is always on.
I have changed the bd20 but it still lights on the AIU.
There is only one wire going through the bd20.
When I disconnect the bd20 the led turns off.
I have cleaned the track but am at a loss as to what to try next.
Thanks,
Richard from Tasmania
Re: BD20

Don Vollrath
 

On Thu, Mar 21, 2019 at 07:17 AM, Richard_vanRaay wrote:
I have changed the bd20 but it still lights on the AIU.
When I disconnect the bd20 the led turns off.
Try a different input channel on the AIU. If that doesn't work... The only thing left is current leakage as seen by the BD20 on/from the track. Verify that the rail gaps are open. Look for debris on the track. Look for current leakage between the rails due to moisture in the ballast. Uninsulated wiring?
DonV
Re: BD20

Richard_vanRaay
 

Thanks Ron. I have checked that following your suggestion. That is not the cause.
Cheers.
Re: BD20

RONALD ST.LAURENT
 

Hi Richard,

Another thing to check would be continuity with a VOM at each gap.  You should see no continuity, if you do, there's the area of the problem.

Ron

On Thursday, March 21, 2019, 3:58:10 PM EDT, Richard_vanRaay via Groups.Io <richard_vanraay@...> wrote:


Thanks Ron. I have checked that following your suggestion. That is not the cause.
Cheers.

Re: BD20

Marcus Ammann
 

Hi Richard

 

If you cannot find any issues with what others have suggested, then desensitized the BD20 as per the Manual at:

 

https://ncedcc.zendesk.com/hc/en-us/article_attachments/200585095/Bd20a.pdf

 

Regards

Marcus

Layout Video https://youtu.be/biFOG0e6IHo

Web Site http://www.members.optusnet.com.au/nswmn/

 

 

From: w4dccqa@groups.io [mailto:w4dccqa@groups.io] On Behalf Of Richard_vanRaay via Groups.Io
Sent: Friday, 22 March 2019 6:54 AM
To: w4dccqa@groups.io
Subject: Re: [w4dccqa] BD20

 

Thanks Ron. I have checked that following your suggestion. That is not the cause.
Cheers.

 

Virus-free. www.avg.com

 
Re: BD20

Richard_vanRaay
 

Thanks everybody for your help. I feel really simple but have to admit it was a very simple problem. I had changed some wiring onto a turnout and that bypassed the BD20. 
Thank you all again.
🤗
Re: BD20

Don Vollrath
 

Thanks for the feedback Richard. Glad you found the problem. and glad to have helped.
DonV
Re: BD20

Jerry Michels
 

Don,

In you rpost you mention current leakage.  I think we see this on our layout when I check certain blocks with a LED tester we use to ensure correct phasing between blocks.  In some locations, If I check for proper phasing between blocks, when I connect opposite rails (e. g. block 1 rail A and block 2 rail B) I get the proper bright LED indication, but if I connect the same rails (rail A to rail B) I get a very faint glow. I take it that this is an indication of current leakage?  We are in a very dry environment, so moist ballast is not a concern, so perhaps debris working it way into gaps may be the problem, or gaps closing with temperature.  Interesting research project.

Thanks,

Jerry Michels
Amarillo Railroad Museum
Re: BD20

whmvd
 

Great news, even if I won't claim to understand why it would have shown 'occupied' in that situation. But never mind - enjoy!
Wouter


On Fri, 22 Mar 2019 at 12:30, Richard_vanRaay via Groups.Io <richard_vanraay=yahoo.com@groups.io> wrote:
Thanks everybody for your help. I feel really simple but have to admit it was a very simple problem. I had changed some wiring onto a turnout and that bypassed the BD20. 
Thank you all again.
🤗

Re: BD20

Don Vollrath
 

Jerry,
LEDs can be very sensitive and so are your eyes. remember that the DCC signal/power voltage is actually flipping in +/- polarity several thousand times per second and that every wire and electrified rail has a small amount of capacitance to other objects. Charging and discharging that capacitance from that rail or wire to other objects, even if they are supposedly not electrified, will let current flow through a test LED to temporarily electrify the 'other side' with a repetitive amount of current to flow... a few hundred micro-amps perhaps, which can be great enough to dimly light up a sensitive LED so that your eyes can see it. The BD20 on the other hand supposedly requires maybe 8-10 milli-amps of current for track occupancy detection. Long leads of twisted pair wiring and/or the track itself can form enough 'leakage capacitance' and DCC leakage current flow to fool a current sensitive occupancy detector like the BD20. This why it is best to place a BD20 out by the track section to be measured and not use twisted pair wiring placed after the sensor.

Just for giggles notice in some situations just holding the other LED test lead in your hand forms enough of a high frequency antenna and power absorption to light up a sensitive LED.

DonV

DonV. 
Re: Forgive my ignorance! Am I creating several reverse loops on my proposed layout?

Tom G.
 

Update - fun part coming. I’m sure I’ll need some of your expertise folks! Hopefully you can see these images. 





Thanks.
Tom

On Mar 13, 2019, at 9:56 PM, Don Vollrath <donevol43@...> wrote:

As updated there are no reversing loops except for the turntable itself.
DonV 

Re: Forgive my ignorance! Am I creating several reverse loops on my proposed layout?

David McBrayer
 

Tom,
The images were cut off by what seems to be a policy of Groups.io. Don’t feel bad about this, you’re not the first to be bitten. And, don’t forget we all started at zero at sometime.

Dave McBrayer
Castro Valley, CA
Wiring For DCC Update Announcement

wirefordcc
 

Don Vollrath's advice for a simple test light for DCC can now be found on my website at:

http://www.wiringfordcc.com/track.htm#a29

Allan Gartner
Wiring For DCC
Re: Wiring For DCC Update Announcement

Jerry Michels
 

Hooray!  Just the information I needed.  Jerry Michels
Buss wire

PennsyNut
 

I am new to this group. Just have a simple question. If a buss wire "should" be AWG14. Would two AWG 20's twisted/soldered together be sufficient. All the stuff I see is so complicated and overwhelming to me that I don't understand wires. I note that two AWG 20 gauge wires are the same size as AWG 14. And when I test with a meter, see no voltage drop with the "double twisted soldered" wires. In fact, the DC voltage and amperage is the same when tested with loco on track. I hope I'm clear, and just want clarification on wire size.
Morgan Bilbo, new to DCC
Re: Wiring For DCC Update Announcement

Richard Gagnon <richg_1998@...>
 

Some will not believe it but my four Harbor Freight multimeters mesure 13.6 vac for my NCE power cab which is good enough for me.
I measured with my Scope and did the math. Very close.
Same at the club some years ago which had the five amp power pro. 
I found a circuit online that uses the 20ma current scale and a couple three terminal chips and a couple other things to make it an accurate five amp DCC amp meter for under ten dollars. I made two.

Rich





On Monday, March 25, 2019, 5:37 PM, wirefordcc <bigboy@...> wrote:

Don Vollrath's advice for a simple test light for DCC can now be found on my website at:

http://www.wiringfordcc.com/track.htm#a29

Allan Gartner
Wiring For DCC

Re: Buss wire

David McBrayer
 

Morgan, 
re doubling up wire. 
If you parallel two no. 20 AWG conductors, the resulting combined cross-sectional area would be approximately the same as a no. 17 AWG conductor.  
To get the approximate equivalent of a no. 14 AWG conductor you would need to parallel four no. 20 AWG conductors.  Paralleling conductors is fraught with long term reliability issues.  The issues can be managed but they are not the least expensive way to go.  

I suggest you do a web search for “wire table” to see the bigger picture of how AWG wire sizes are related.  AWG numbers have no direct relationship to cross-sectional area, which does relate to current carrying rating.  See also “metric wire table” to see how they relate.  

Yes, you can do it but be sure to notice how much hair you have (or don’t have 😉) when start troubleshooting some day down the road. 

Dave McBrayer 
Castro Valley, CA 


On Mar 26, 2019, at 12:24, PennsyNut <pennsynut@...> wrote:

I am new to this group. Just have a simple question. If a buss wire "should" be AWG14. Would two AWG 20's twisted/soldered together be sufficient. All the stuff I see is so complicated and overwhelming to me that I don't understand wires. I note that two AWG 20 gauge wires are the same size as AWG 14. And when I test with a meter, see no voltage drop with the "double twisted soldered" wires. In fact, the DC voltage and amperage is the same when tested with loco on track. I hope I'm clear, and just want clarification on wire size.
Morgan Bilbo, new to DCC

Re: Buss wire

Carl
 

Hello Gang:

I wouldn't say parallel conductors is "fraught with long term reliability issues". It is done in industrial wiring when they don't want to buy or string OOO wire.  There are rules though:

1) don't put all the same conductor in one metal conduit ( induced currents )

2) each conductor needs its own circuit protection ( fuse or breaker )

3) clearly mark each conductor ( we should be doing this anyway )

The main reason for the heavy wire is for fault protection. I use heavy industrial wire, Oilflex and similar, 2mm dia.

Carl.

On 3/26/2019 5:16 PM, David McBrayer wrote:
Morgan, 
re doubling up wire. 
If you parallel two no. 20 AWG conductors, the resulting combined cross-sectional area would be approximately the same as a no. 17 AWG conductor.  
To get the approximate equivalent of a no. 14 AWG conductor you would need to parallel four no. 20 AWG conductors.  Paralleling conductors is fraught with long term reliability issues.  The issues can be managed but they are not the least expensive way to go.  

I suggest you do a web search for “wire table” to see the bigger picture of how AWG wire sizes are related.  AWG numbers have no direct relationship to cross-sectional area, which does relate to current carrying rating.  See also “metric wire table” to see how they relate.  

Yes, you can do it but be sure to notice how much hair you have (or don’t have 😉) when start troubleshooting some day down the road. 

Dave McBrayer 
Castro Valley, CA 


On Mar 26, 2019, at 12:24, PennsyNut <pennsynut@...> wrote:

I am new to this group. Just have a simple question. If a buss wire "should" be AWG14. Would two AWG 20's twisted/soldered together be sufficient. All the stuff I see is so complicated and overwhelming to me that I don't understand wires. I note that two AWG 20 gauge wires are the same size as AWG 14. And when I test with a meter, see no voltage drop with the "double twisted soldered" wires. In fact, the DC voltage and amperage is the same when tested with loco on track. I hope I'm clear, and just want clarification on wire size.
Morgan Bilbo, new to DCC

Virus-free. www.avast.com

Re: Buss wire

David McBrayer
 

Carl, 
I take your point.  However, this is about a low voltage tabletop model railroad not the Northeast Corridor. 

Dave McBrayer


On Mar 26, 2019, at 20:18, Carl <carl.blum@...> wrote:

Hello Gang:

I wouldn't say parallel conductors is "fraught with long term reliability issues". It is done in industrial wiring when they don't want to buy or string OOO wire.  There are rules though:

1) don't put all the same conductor in one metal conduit ( induced currents )

2) each conductor needs its own circuit protection ( fuse or breaker )

3) clearly mark each conductor ( we should be doing this anyway )

The main reason for the heavy wire is for fault protection. I use heavy industrial wire, Oilflex and similar, 2mm dia.

Carl.

On 3/26/2019 5:16 PM, David McBrayer wrote:
Morgan, 
re doubling up wire. 
If you parallel two no. 20 AWG conductors, the resulting combined cross-sectional area would be approximately the same as a no. 17 AWG conductor.  
To get the approximate equivalent of a no. 14 AWG conductor you would need to parallel four no. 20 AWG conductors.  Paralleling conductors is fraught with long term reliability issues.  The issues can be managed but they are not the least expensive way to go.  

I suggest you do a web search for “wire table” to see the bigger picture of how AWG wire sizes are related.  AWG numbers have no direct relationship to cross-sectional area, which does relate to current carrying rating.  See also “metric wire table” to see how they relate.  

Yes, you can do it but be sure to notice how much hair you have (or don’t have 😉) when start troubleshooting some day down the road. 

Dave McBrayer 
Castro Valley, CA 


On Mar 26, 2019, at 12:24, PennsyNut <pennsynut@...> wrote:

I am new to this group. Just have a simple question. If a buss wire "should" be AWG14. Would two AWG 20's twisted/soldered together be sufficient. All the stuff I see is so complicated and overwhelming to me that I don't understand wires. I note that two AWG 20 gauge wires are the same size as AWG 14. And when I test with a meter, see no voltage drop with the "double twisted soldered" wires. In fact, the DC voltage and amperage is the same when tested with loco on track. I hope I'm clear, and just want clarification on wire size.
Morgan Bilbo, new to DCC

Virus-free. www.avast.com

Re: Buss wire

Mark Gurries
 

Yes using a large enough gauge wire will satisfy fault protection.  Doing a coin short circuit test will verify if a given section of track is wire sufficiently to allow fault protection.   But the very next reason above fault protection  is to make sure trains maintain a given speed consistently when you run long wires..

A 1.2V drop at 120V represents a 1% voltage drop.  No problem.  But the same 1.2V drop at 12V, is a 10% drop.  That will translate in a 10% drop in train speed.

On Mar 26, 2019, at 9:21 PM, David McBrayer <d_mcbrayer@...> wrote:

Carl, 
I take your point.  However, this is about a low voltage tabletop model railroad not the Northeast Corridor. 

Dave McBrayer


On Mar 26, 2019, at 20:18, Carl <carl.blum@...> wrote:

Hello Gang:

I wouldn't say parallel conductors is "fraught with long term reliability issues". It is done in industrial wiring when they don't want to buy or string OOO wire.  There are rules though:

1) don't put all the same conductor in one metal conduit ( induced currents )

2) each conductor needs its own circuit protection ( fuse or breaker )

3) clearly mark each conductor ( we should be doing this anyway )

The main reason for the heavy wire is for fault protection. I use heavy industrial wire, Oilflex and similar, 2mm dia.

Carl.

On 3/26/2019 5:16 PM, David McBrayer wrote:
Morgan, 
re doubling up wire. 
If you parallel two no. 20 AWG conductors, the resulting combined cross-sectional area would be approximately the same as a no. 17 AWG conductor.  
To get the approximate equivalent of a no. 14 AWG conductor you would need to parallel four no. 20 AWG conductors.  Paralleling conductors is fraught with long term reliability issues.  The issues can be managed but they are not the least expensive way to go.  

I suggest you do a web search for “wire table” to see the bigger picture of how AWG wire sizes are related.  AWG numbers have no direct relationship to cross-sectional area, which does relate to current carrying rating.  See also “metric wire table” to see how they relate.  

Yes, you can do it but be sure to notice how much hair you have (or don’t have 😉) when start troubleshooting some day down the road. 

Dave McBrayer 
Castro Valley, CA 


On Mar 26, 2019, at 12:24, PennsyNut <pennsynut@...> wrote:

I am new to this group. Just have a simple question. If a buss wire "should" be AWG14. Would two AWG 20's twisted/soldered together be sufficient. All the stuff I see is so complicated and overwhelming to me that I don't understand wires. I note that two AWG 20 gauge wires are the same size as AWG 14. And when I test with a meter, see no voltage drop with the "double twisted soldered" wires. In fact, the DC voltage and amperage is the same when tested with loco on track. I hope I'm clear, and just want clarification on wire size.
Morgan Bilbo, new to DCC

Virus-free. www.avast.com

Best Regards,

Mark Gurries
Electrical Engineer
DCC Website & NMRA DCC Clinics: www.markgurries.com