circuit board and wiring locations?

[gregc]

i'm curious about opinions on locating circuit boards to minimize wiring and maximize maintainability and convenience access.

I'm building circuit cards for block detection and servo control of semaphores.   A circuit card typically has one or more power (PWR) connections, interfaces (I/F) to electrical devices located on the layout (e.g. servo, LEDs, photo transistors, track) and possibly control (CTL) signals from a control panel.

there appear to be 3 possible locations for circuit cards:

1. directly under the device they interface to on the layout, minimizing I/F wiring but requiring that PWR and CTL be wired throughout the layout.  They may also be inconvenient to access.
2. directly in front of the device, mounted near the fascia for convenient access.   This requires longer I/F connections, but PWR and CTL can run as a group of wires behind the fascia as Lion suggested in the March '14 MR.
3. all circuit cards are mounted at one location, minizing PWR and CTL but requiring longer I/F connections. Certainly convenient to access, but requires labeling to avoid a confusion if many devices.

thanks

[peahrens]

May depend on your layout size.

I have a smallish layout, 5x10 or so, and have all my electronics on an L-shaped shelf that I connected between the legs on one end.  It is two 1x8s, and provides a shelf for a power strip, DCC main parts, etc and the backboard is nice for putting circuit boards and fuse holders, etc where it is easy to add and wire them. 

[BroadwayLion]

LION went with putting the stuff in a central location...

There is one relay pair for every block [station edge]. Since there must be four conductors between adjacent blocks for my analog system to work, I found my self using about the same amount of wires as if I put the relays locally at each station. Indeed, that is how I started bulding the system, but as mistakes appeared, and trouble shooting became difficult, I moved everything to this centrail location. There are 210 conductors from this board to the layout, five for each block/platform edge. If you buy 25 pair cat-3 cabling, you could call it five or six runs from here to there. (Add one conductor for each Tortoise machine, the switch machine manages signal logic locally for the interlockings.)

Of course da LION controls the entire railroad from this interlocking plant...

And so him has no remote switch locations around the layout.

But the LION cheated, him put four or more signals in each block, so a signal does not drop to red until the train clears the entire block. Him wishes that him could have built it with more selective controls, but that would require hundreds more detectors and relays. Still, there is no reason why I could not in the future install local relays for a more realistic operation in places where the issue is obvious.

Perhaps you could call this board my netwrok interface card...

And here are the local device control points. This is of course just after the cables were installed, and before the local devices were connected to them.

The pin-out for each platform edge (The Prospect Park station above has four platform edges, as does the 34th Street station on the other side of this table although the controls for that station are located here) is this:

1) Track Detector Circuit. Detects a train ariving at this location.

2) RED signal for previous block

3) YELLOW signal for previous block

4) GREEN signal for previous block

5) Timer Relay to release the train to the next block. This will not pull if the next block is red, so the train will hold until the block clears. Without the stations it would just enforce the red signal beyond it.

It was a lot of work, and while all of the control wiring is in place, I still have about 70 signals to build and place.

ROAR

[rrinker]

 It all depends on how it's controlled. With my Digitrrax system and Loconet, it's easy to distribute modules near the devices they control because the control bus is nothing more than a 6 conductor phone cable running from device to device. A single power bus, and careful chocie of devices, is the only other thing. Say a 15V AC power bus, with rectifiers and DC/DC converter modules (cheap) to get DC and/or reduced voltages for devices that need less.

 Likewise, my fascia controls will also be Loconet devices - so that they can directly control the accessory decoders for turnouts when operating alone, or be fed via JMRI panels for when a dispatcher is on duty. There may be a coupel of dozen buttons on a large panel, yet it will plug intot he layout via one 6 pin phone cord plus 2 wires to the power bus.  I am determined to NOT have a maze of wires under my layout, except perhaps locally where a signal detector and controller board is with wires from each detector and to each signal. Between OS sections - nothing but the track power bus, accessory power bus, and a Loconet cable. And no long track power bus runs - boosters will be distributed, so that no bus run will need to exceed 30 feet or so from a booster.

                 --Randy

[BroadwayLion]

You lost me when you said "Loconet". With over 200 signals on the layout, buying controllers of any sort for them is a non-starter. LION will build what he can with what he has, and let the rest go.

LION watches no TV, and so does not know how to use a remote. Him is not using a remote to run a railroad. Him *like* the big paw-sized levers of him. And you *know* what each one is going to do without twiddling a lot of knobs or buttons.

No knobs, buttons or switches on the layout of LION. No Throttles, no reversing swithches. Turn it on, the trains run. LION can operate the interlocking plant at 242nd Street, other than that it is all up to rhe LPPs.

ROAR

 

ROAR