Author Topic: Detectors  (Read 1220 times)

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PaulP

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Detectors
« on: January 05, 2014, 02:21:25 AM »
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So I am working on my signal system. I am using Se8C's  and BD4's from Digitrax. My question is using BD4's you have to have all 4 sections in the same power district. I was wondering if I use 4 of the NCE BD20 single detectors in place of the BD4's could those 4 sections come from different power districts? Also as I read it says you have to use an entire BD4 just to detect one reverse section, seem like a waste. Again wonder if one BD20 single could be used for the reverse loop and then use 2 BD4's for the other 7 detector sections on the SE8C? Any experience with this?

Paul

John

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Re: Detectors
« Reply #1 on: January 05, 2014, 06:19:31 AM »
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the NCE detectors are completely independent and are current sense .. were the BD4s are not .. It's true you need to use the BD4s in one power district .. but that shouldn't be an issue if you wire it correctly ... a signaled passing siding will need 4 sensors ..

The NCE detectors should be able to be used in the reverse loop ..

trainforfun

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Re: Detectors
« Reply #2 on: January 05, 2014, 11:08:34 AM »
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I am thinking of adding signals in the future , is there a book or other printed "how to" that you know of ?
It's ok to detect a train in a siding but is there a system that will also detect on which side is thrown the turnouts ?
What about the logic of all this , the siding is occupied but if the turnout is thrown there should be an indication on the lower light of the mast . Upper light in red and lower light in green , or reverse if the other track is occupied see what I mean .
Thanks ,
Louis



John

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Re: Detectors
« Reply #3 on: January 05, 2014, 01:16:55 PM »
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I am thinking of adding signals in the future , is there a book or other printed "how to" that you know of ?
It's ok to detect a train in a siding but is there a system that will also detect on which side is thrown the turnouts ?
What about the logic of all this , the siding is occupied but if the turnout is thrown there should be an indication on the lower light of the mast . Upper light in red and lower light in green , or reverse if the other track is occupied see what I mean .

JMRI .. that is the way I went ..   I'm having a bunch of shoulder pain right now, and it hurts to type .. I will add more later

www.jmri.org

trainforfun

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Re: Detectors
« Reply #4 on: January 05, 2014, 02:59:33 PM »
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Wow ! I already use it to program speed tables and all . Will go thru the site you sent .
Thanks !
Thanks ,
Louis



bdennis

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Re: Detectors
« Reply #5 on: January 06, 2014, 04:04:33 AM »
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So I am working on my signal system. I am using Se8C's  and BD4's from Digitrax. My question is using BD4's you have to have all 4 sections in the same power district. I was wondering if I use 4 of the NCE BD20 single detectors in place of the BD4's could those 4 sections come from different power districts? Also as I read it says you have to use an entire BD4 just to detect one reverse section, seem like a waste. Again wonder if one BD20 single could be used for the reverse loop and then use 2 BD4's for the other 7 detector sections on the SE8C? Any experience with this?
Paul

Paul,
Just be careful with the BD20 and the SE8C. The detection input on the SE8C is expecting the 5V rail to be high to provide a detection input, where are the BD20 is the opposite.  I looked into using these, and while it can be done there is extra build your own electronics needed to make them work together.
I would not recommend the BD4's from Digitrax as they will cause false detection when used with current day decoders as they have not been updated. (Silly Digitrax!)

Also remember that the SE8C will not set any signals based on the Detection input. It requires a Computer with an application such as JMRI to detect the block and then take an action to change a signal.

If you want an automated system then can I suggest the Teamdigital SIC24AD. It has built in logic that can drive signals based on detector inputs with out a computer. They also have block detectors such as the BlockD8.

As I have a Digitrax system my weapon of choice is a BDL168 block detector or a TC64 from RR-Cirkits in conjunction with JMRI.
Brendan Dennis
N scale - Delaware & Hudson Champlain Division

John

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Re: Detectors
« Reply #6 on: January 06, 2014, 04:59:28 PM »
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As I have a Digitrax system my weapon of choice is a BDL168 block detector or a TC64 from RR-Cirkits in conjunction with JMRI.

+1 on the RR-Circuits stuff .. also, they have a real nice set of block detectors as well ..  and good folks to do business with

PaulP

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Re: Detectors
« Reply #7 on: January 06, 2014, 10:42:41 PM »
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Thanks Guys

 I am using JMRI for the logic. I am using one old ds54, 2 SE8C's, 3 BD4's and a BDL168 on  a Super Chief system. My original question was pertaining to my reverse loop. I either have to use a quad section of my BDL168 or use a BD4 with the SE8C which seems like a waste of detectors. I was thinking I might be able to use three of the sections of a BD4 for detection sections and one NCE BD20 for my reversing loop in the fourth spot. Since the BD20 does not electrically connect to the track power I assumed it turned on the transistor and let current flow between the output wires. Which in turn would conduct between the common and the sensor terminal on the SE8C. Is that not what a BD4 does makes current flow from common to sensor terminal on the SE8C. I didn't know either kind of detector produces any kind of polarity or voltage. I also figured a single detector could handle the phasing change on the reverse loop. Maybe one sensor is a PNP and one a NPN. Will have to research more.

Louis
 Yes JMRI will take into account turnout position and blocks occupancy to control your signals. I feel like signaling has a learning curve like DCC was at the start but the more I work with it the easier it is to understand.

Brenden
  Guess I have been lucky for my BD4's have been working great. I will keep an eye on them though.

Paul

trainforfun

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Re: Detectors
« Reply #8 on: January 07, 2014, 04:37:55 PM »
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One day I will take a plunge !!!
Thanks ,
Louis



bdennis

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Re: Detectors
« Reply #9 on: January 07, 2014, 06:42:05 PM »
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Paul,
Thanks for the update.
All is now much clearer...

In terms of the SE8C inputs, they require 5V to be supplied to the input to make it detect. There as the BD20's have a output that pulls to ground.
I think what is needed to make them work together is a PNP transistor that enables the Active Low on the BD20 to be converted into a Active high and providing a switch to turn on and off the 5v needed on the SE8C..

I looked at doing it but gave up and opted for BDL168's.
Of note, I also used the 16 outputs on the BDL168's that are used to show occupancy and decoupled them from the blocks and then use them to drive signals via optocouplers.
Brendan Dennis
N scale - Delaware & Hudson Champlain Division

John

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Re: Detectors
« Reply #10 on: January 07, 2014, 06:47:04 PM »
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no matter what detector you use, pick one and try to stick with it .. in my case, I have a mixture, and its tough sometime to remember how i wired it all up