# How big are you blocks?



## detz (Dec 19, 2014)

What's a good rule of thumb if there is one?


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## feldon30 (Dec 30, 2012)

We can only assume you have a DCC layout with 18 gauge bus wire to terminal blocks and 22 gauge drops from the terminal strips/blocks, with drops soldered to your rails every 3 feet. Might also help to know how big your booster is. On our layout, we are using two Digitrax PM42 circuit breakers which each have four outputs.

PM42 #1:

Mainline West
Yard #1
Yard #2
Switchits (power/controller for all West-side Tortoises)

PM42 #2:

Mainline East
Yard #3
Yard #4
Switchits (power/controller for all East-side Tortoises)

PM42 #3 (soon!):

Mainline Upper
Helix
(future expansion)
(future expansion)

Our turnouts (Peco Electrofrogs) have insulating rail joiners on both ends, with all rails of the turnout powered from the yard power and the frog powered from the associated Tortoise.

With this arrangement, a short in a yard does not take down the whole layout, and a short will never prevent us from being able to throw a mainline turnout from the panel or JMRI. We did have to increase the minimum breaker time on our Digitrax booster to be longer than the minimum breaker time on the PM42, otherwise every short tripped the entire layout.


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## DonR (Oct 18, 2012)

Feldon has provide a good example of how it can be done.

How big is your layout detz. Do you feel that it is large
enough that you need to break up the electric feed
system?

I have a room size DCC HO layout and do not have
a need for blocks at this point.

Don


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## feldon30 (Dec 30, 2012)

Size absolutely matters. If you are on a 4x8 or even 4x12 layout you probably don't even need blocks. My above post is applicable to a 21 x 23 layout that will be double-decker for 2/3 of the room.


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## D&J Railroad (Oct 4, 2013)

I'm using three power districts with a PM42 a DCS100 in one and DB200s in the other two. The DCS100 is used in the mountainous area of the layout where there will be less industry or accumulation of motive power. I'm using the Digitrax PS2012 power supply to feed the entire layout. My empire is 6.5 scale miles of double track mainline with industrial sidings popping up all over it as I develop it. My principle is to provide more power than I think I will need.


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## wvgca (Jan 21, 2013)

i have around a 16X16 single deck and origionally set it up with eight power districts, but have never gotten around to cutting gaps to make the sections individually active, but i normally run by myself, more track [ i have appx 300 ft total, about 5 scale miles]or more operators may require block sections to keep a short for halting other users , plus it would make it easier to find a short when it does happen...required...no, recommended, yes...when i get a short all my power indicator lights flicker, but most times it's a metal tool i accidentally left in the wrong place ...i updated the power supply on my mrc prodigy express, but 2.5amp doesn't cause any damage when it does short..


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## detz (Dec 19, 2014)

I was more thinking about signal control vs power or anything. My layout isn't built everyone is on paper thus the question but it's going to be a dogbone type 11'x5' on the ends and 3' in the middle. I'm thinking I can have two main tracks and one for the corners with turnouts but I was thinking for block detection I might want to split it up to make the signals "cooler".


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## DonR (Oct 18, 2012)

Block occupancy detection for controlling track side signals or panel lights
can get pretty complex and costly in HO.

There are commercially available electronics to do this and
you can see some in action in videos from some of
the larger layouts.

If this is what you have in mind there are a few members of
the Forum who have had experience with it and could guy
you.

Don


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## feldon30 (Dec 30, 2012)

detz said:


> I was more thinking about signal control vs power or anything. My layout isn't built everyone is on paper thus the question but it's going to be a dogbone type 11'x5' on the ends and 3' in the middle. I'm thinking I can have two main tracks and one for the corners with turnouts but I was thinking for block detection I might want to split it up to make the signals "cooler".


If you just want crossing signals with gates, those can be done with infrared detectors.

If you want true block occupancy detection, then you're going to increase the complexity of your layout significantly. As far as I know there are really only two reliable solutions to BOD:

Adding a small *resistor *to the trucks on every piece of rolling stock in your collection.
Adding an *RFID tag* to one truck on every piece of rolling stock in your collection.
The cost of each is pennies per car, but the labor!

After looking long and hard at both choices, we are probably going to go with RFID. Roughly the same cost/difficulty to implement as resists, but then *we'll know exactly WHICH cars are in which yards, spurs, industries*, etc. and be able to *fully automate the printing of Car Cards*. After talking to other guys who have to sit in MS Word for 3-4 hours on a Sunday afternoon, wrestling with making cards, we'll be able to walk around our layout with an RFID scanner, sweep each yard, and then press a button on the computer and it will print out the car cards for us. Then all we have to do is cut the printouts on a paper cutter.


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## detz (Dec 19, 2014)

feldon30 said:


> If you just want crossing signals with gates, those can be done with infrared detectors.
> 
> If you want true block occupancy detection, then you're going to increase the complexity of your layout significantly. As far as I know there are really only two reliable solutions to BOD:
> 
> ...


How would the rfid work without a reader at ever block?


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## Shdwdrgn (Dec 23, 2014)

@feldon30 - Can you tell me where you found cheap RFID tags? I was trying to look into them for the same reason - to know where each car was located - but the systems I found were prohibitively expensive. Also are there any RFID readers available cheaply (< $10) so I could afford to put one in each yard and various spots along the mainline?


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## detz (Dec 19, 2014)

Shdwdrgn said:


> @feldon30 - Can you tell me where you found cheap RFID tags? I was trying to look into them for the same reason - to know where each car was located - but the systems I found were prohibitively expensive. Also are there any RFID readers available cheaply (< $10) so I could afford to put one in each yard and various spots along the mainline?


The rdm630 chip works but you only get a read distance of about 3/4" so you'd have to put it right below the track and have the tag on the bottom of the stock with something like this: https://www.sparkfun.com/products/9417

Still adds up fast but I guess no more then current sensors.


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## JerryH (Nov 18, 2012)

My HO layout is 11x6 double track and I use about 30 blocks. The original atlas plan used about 8. The average block is 3 - 4 feet. The reason I used so many extra blocks was to provide room for running a very congested train schedule on too small of layout for automation. I put a 10K 1/8th watt resistor on one axel of each car that normally draws no power for detection. You need to decide how many blocks will meet your operational needs. You may find some interesting info that may help you in the following thread.

http://www.modeltrainforum.com/showthread.php?t=14852


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## fcwilt (Sep 27, 2013)

detz said:


> Still adds up fast but I guess no more then current sensors.


You likely will still want current sensors.

Reed switches, Hall Effect devices, IR sensors and RFID sensors are "point" or "location" sensors. 

They tell you when a detectable piece of rolling stock has reached a certain location.

Current sensors are "occupancy" sensors. 

They tell you when a detectable piece of rolling stock is anywhere in the stretch of track served by the current sensor.


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## Shdwdrgn (Dec 23, 2014)

A quick update regarding RFID... thanks for the keyword "tag", as I wasn't having good luck searching to "RFID chip". They can definitely be found for less than $1 each, and I have even found RFID stickers.

However my searching has also led me to the discovery of NFC devices, which seems to be a close cousin of RFID, with a difference. These devices have a block of memory, which you custom-write with the information you want to store. Range is 1-4 inches, good for embedding the readers right under the track. Again, the tags can be purchased as stickers, 25mm round dots (I've seen hints of some as small as 10mm but haven't found them yet). I am finding the stickers for as little as 46 cents each with 144 bytes of memory. I located some readers (model MFRC522) with an SPI interface for under $4 which are 40x60mm and nearly flat. It is capable of reading multiple tags at once. The programmers are about $20, but you'd only need one of them.

NFC is apparently also being built into some smartphones like the Galaxy series, so you might not even need to buy a programmer.

[EDIT] Apparently, I use too many, commas. Sorry about that.


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## feldon30 (Dec 30, 2012)

There is an RFID for RR group on Yahoo:
https://groups.yahoo.com/neo/groups/RFID4MRR/conversations/messages

The two main guys (Seth and Chris) have written extensive articles on all the parts needed, the limitations, the installation process, etc. One of their big articles was even in Model Railroader this year and explains pretty much everything about it. Here's their presentation from NMRA 2013:
http://bayrails.com/layouts/neumann/RFID in Model Railroading 20130629.pdf

Yes, with RFID you don't technically have block occupancy so much as awareness of placement. When you turn on your layout, you'd walk around the entire layout with your handheld RFID scanner and wave it over staging, each yard, each industry, and then the computer knows where everything is. Then you have short distance readers installed under the rails before and after each Yard or anywhere else there's a crossing. You end up with a constantly updated database of which cars are where. A side benefit is, we'll be able to automate the printing of car cards and I'm hoping to be able to "audition" or "test run" an op session, with the computer determining which cars will be picked up and dropped off after each train goes through, and then see which yards will be overflowing with cars. Then we can make adjustments or leave a few cars off so there's room on the train to pick up extra eastbound or westbound cars.

The RFID tags these guys have found cost $2 for 100 and the stationary readers you install under the tracks including the small circuit board and other hardware cost about $100 per reader. They're working to get the price down on the readers.

If that sounds way too technical or expensive, then resistors is the way to go as it will tell you "is the mainline between yard 1 and yard 2 clear?" or "is the mainline switch on the east end of yard 1 clear?"


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## DonR (Oct 18, 2012)

Jerry


Do all those cars with a resistor 'load' on each add much
in the way of current drain on the track? In the past, I've looked at
using a 'resistance' paint that does the same thing. Have
you tried that.

Don


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## feldon30 (Dec 30, 2012)

DonR said:


> Jerry
> 
> 
> Do all those cars with a resistor 'load' on each add much
> ...


I took a class on resistance wheelsets and installing them and all that and when the subject came up, we were told that even dozens of cars add a barely noticeable load.

One thing we found:

*Kadee *wheelsets are a pain because you have to rub off the weathering. Also they use a plastic axle so you have to paint a line of conductive paint all the way from one end of the axle to the other, on top of the resistor. We tried just using resistance paint and it was tricky to get it to work consistently. The resistors come in spools of a thousand, so again it's just the labor of installing these things which are 1/3 the size of a grain of rice at a 45 degree angle!

*Intermountain *are far easier as they have a metal axle, have no weathering you have to clean off, and you just have to glue the resistor so it bridges across the thin black plastic band that isolates the left from the right. If I were doing resistance wheelsets, I would build a jig to hold the wheelset at a 45 degree angle so I can install the resistor more easily. You have to have plastic trucks though.


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## JerryH (Nov 18, 2012)

I am sure they increase the load some, but it is not apparent on the ammeter on the power supply. Probably very little in the overall scheme. Never tried the paint as it seems trickier to get a uniform resistance with it.


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## DonR (Oct 18, 2012)

Do you add wipers? How are the resistors
attached to the trucks to make contact to
the wheels?

I use some Kadee wheels with wipers against
the back of the wheel. They apparently are
making electrical contact.

Don


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## Shdwdrgn (Dec 23, 2014)

What size of resistors are you using? I did a calculation once, and found that a 10k resistor at 12V only adds about 1mA of current draw.


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## JerryH (Nov 18, 2012)

I drilled tiny holes in the wheels just above the axle and ran the resistor leads through them. I then clipped them and bent them over. This is easy, cheap, and works for me.


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## feldon30 (Dec 30, 2012)

If you happen to have the really small resistors, then here are the rough drawings I made of the installation on either plastic or metal wheelsets:



















Just how small are these resistors?


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## fcwilt (Sep 27, 2013)

Wipers that touch the wheels are only needed if you want to get the power into the car, say, for lighting.

The resistor only needs to have conductivity to each wheel.

One poster said that to use Intermountain wheel sets you need to use plastic trucks - I have no idea why they think that.

I started with Intermountain because they are a good wheel set BUT I was also using electro-magnetic uncouplers. The Intermountain wheel sets, being magnetic, prevented reliable uncoupling as the electro-magnetic uncoupler was strong enough to pull the cars out of position.

I purchased a quantity of Kadee wheel sets because they are non-magnetic. They were also somewhat easier to modify as the resistor could be glued directly to the center of the plastic axle. Then I used conductive paint to connect the resistor to the wheels. Yes I did first use my Dremel tool with a wire brush to remove any coating from the back of the wheel, the flange and the "tread".

So far so good and the uncoupling now is reliable - now to see if the wheel sets hold up.


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## Shdwdrgn (Dec 23, 2014)

In case you're curious or need to know the right terminology when ordering parts, the 'really small' resistors are surface-mount components. The ones shown in Jerry's post are through-hole components (looks like 1/8 watt).


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## JerryH (Nov 18, 2012)

Yep, 1/8 watt from Radio Shack near my house.


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