Atlas Signal System Question (Continued From Previous Post Jan. 2010)

[nscsxcrrailfan]

A few months ago I asked a question on here about connecting the NCE BD20 with the Atlas Signal System. A couple of the members on here said that the NCE BD20 uses an open collector output, which allows two (or more) block detectors to talk to one signal. Now, before I really get started on my signal system, I have a couple other questions. First, each block detector (NCE BD20) has to receive power in order to work. Each has a two wire power connection that comes from the Atlas signal board. The Signal board is powered from AC power directly from the Power Supply (I believe DC can also be used). Can I hook up two block detectors to the same Signal board's power connection? Basically, Can two block detectors receive power from one Signal board? What kind of issues will I run into doing this (not enough power for each, etc....)? Second Question, I know I can use two or more block detectors to communicate to one signal board, but can I use one block detector to communicate to 2 or more signal boards?

[CSX Robert]

nscsxcrrailfan

First, each block detector (NCE BD20) has to receive power in order to work. Each has a two wire power connection that comes from the Atlas signal board. The Signal board is powered from AC power directly from the Power Supply (I believe DC can also be used).

To wire it that way, I think you HAVE to use DC. The manual for the Atlas SCB(Signal Control Board) is not very clear on this, and I don't have one to test it with, but it appears the two COM connections are simply common to each other and likewise the two PWR conncetions are common to each other. This means the SCB is not actually powering anything but just passing through what is connected to it, so if you power the SCB with AC it will pass that AC along to the BD20, which I believe is designed for DC power only.

nscsxcrrailfan

Basically, Can two block detectors receive power from one Signal board?

If I am correct and the SCB is just passing the power through, then yes that will work.

nscsxcrrailfan

can I use one block detector to communicate to 2 or more signal boards?

Yes.

[nscsxcrrailfan]

O.k., I think I know what I have been doing wrong. I've been using AC power instead of DC. I tested the system out today and hooked up one block detector to two signal boards. It worked, but I noticed that a block detector nearby acted very weird every time I moved it. It's red led light would flicker uncontrollably, and the red led light on the signal board would go off and on. It even had an effect on the signal board next to it. I completely disconnected that block detector from the signal board, and it and the nearby signal board still acted strange. So, I need to stop using AC power with the NCE BD20. I could use my Power Pack's DC throttle, but I'd be afraid of accidentally pushing the throttle up too high causing a voltage overload. I have an Enercell 300ma 9V DC power supply. Could I use it to power the signal system? Would it have enough power (300ma)? Also, the main concern I had was possibly overloading the signal control board's power connector by having two or more block detectors fed from it. Is there a limit to the number of block detectors that can be powered through a single signal control board? Can I attach one wire to each screw-down connection on the signal board and then split each wire to go to each block detector's power input?