Train Turnout & Signal Control Design (Part 1)

 

As I continue to work on the train layout, one thing I am realizing is that I dont have enough turnout and signal control boards from the previous build 10 years ago.  That design had a few issues and was more complicated than it needed to be.  So I did an update, corrected a few errors, made changes for parts that are not available right now and simplified the design.  

One big change was driving the relays in the turnouts and signals.  I need to drive relays in the turnouts/signals for 100ms to 400ms, depending on the type, and only one at a time is ever activated.  

The first issue is providing enough drive to fully turn on the FET, thus lowering Rds and reducing heat.  With 3.3VDC that can be problematic depending on the FET.  I need flexibility in buying so I am wanting to use 5VDC.  The MSP23S8 I/O Expander has to run at 3.3V, because the interface to the PIC runs only at 3.3V.  But the I/O expander has open drain outputs good to 5.5VDC, so it seems attaching a pull-up resistor to 5VDC will improve my drive problem, since a Vgs of 5V will fully turn on most of these FETs.

The next issue is at startup when nothing is defined.  The MSP23S18 I/O pins are inputs on reset, which will float the GATE of the driving FET.  If the BIAS point (see schematic) is connected to 5VDC, then until the MSP23S18 is programmed and all of the outputs are set to zero, all of the FETs will be on.   This will not be good for the relays as the relays in a turnout will be fighting each other.  So I came up with an idea of a BIAS control.  A single FET connected to a PIC I/O pin.  This  will hopefully do the following:

On POR:  RB0 will be an input, Rin will turn the FET on enough to drive the BIAS point to GND.  This should turn off all the relay FETs and everything will be stable. 
Initialization:  Once RB0 is set as an output it will be set high, to keep the BIAS point at GND while the MSP23S18 is initialized for the outputs to be all ZERO.
Finally:  Once the MSP23S18 is initialized, then RB0 can set to ZERO, which will change the BIAS point to 5VDC.  

Below is a reduced schematic of how this will be done.

Year 2022, Where are we headed

 

 

As the New Year dawns, here are the goals for 2022.

Lego Shows to attend

These are the shows we are planning on attending in 2022.  In all cases we will be showing our MOC and a few we will be vending.

Brick Fest Live (San Jose)  March 26 & 27

Brick Days (Omaha)  April 23 & 24

Bricks by the Bay  Jun 23-26

 

Brick Fest Live (San Diego)  Dates TBD

 

Product Development Road Map

Brick Buddy II 

 

 

 

 

 

 

 

 

This really needs to  be done this year and ready for production.  Mostly what is needed to finish is the MP3 section and finalizing the scripting.  This will get added priority this year.

 

Planetary Space Base Expansion

I have some great ideas on how to make this better and bigger. Some of this depends on Brick Buddy II.  I need to continue to build the cliff.  This is largest thing I need to do, but is also the most expensive. 

The two pictures above are renderings of a walker that will roam the cliffs.  I am also working on some construction robots.
 

Train Tools

There are three items here.  These first two are left over from last year.  One I have lots of small displays I acquired years ago.  I want to turn these into billboards for HO train layouts.  They can be loaded with changing displays or a static display.  Also  I have an idea for a battery operated track cleaner.  It would use track power unless the track is too dirty, then it would run on a rechargeable battery. It would also provide real time information back about the track voltage so you could find dead spots via a Bluetooth link and a mobile app.  The final one is to upgrade all of the turnout/signal control units I built 10 years ago and to build a MiWi to Bluetooth interface so I can control the train from a tablet/phone.

 

So we will see if all of this can be done and just how long it will take.

Year 2021 in Review

Another year is done.  Did not get as far as I wanted, but things did get done.

Lego Shows

Bricks By the Bay was fun, even if it was virtual.  Learned a lot that I am now applying to the Planetary Space Base.  Here is hoping that this year will be live and in person.

Nebraska Brick Days was an interesting take on a Lego show.  Different than Bricks By The Bay, but had a lot unique items and a completely different vibe.  First live show I have been to in a while, even though I was just an attendee.  There were a lot more people there than I expected.

Brick Fest (San Diego) was also a lot of fun.  Fairly large crowd, but was just a presentation type show.  Really enjoyed talking with the attendees about what we are doing and how I was inspired to build the Planetary Space base.  I have missed this part of the shows.  That is where the real fun is as a presenter.

Brick Building

Built the NES system, then dropped it on the floor and had to rebuild it.  

 

Continued building on the Planetary Space base.  Started the cliff behind, which is a large undertaking.

 

Train Building

Made good progress on the train layout.  The Grand kids enjoyed watching the limited run on the video chats.  

 

Miscellaneous Building

The Billy Bookcase Hack I did has proved to be very useful. In a small space I have created a maximum  amount of storage space that is easily accessible. And as a plus, it looks good also.  

 

Development Road Map

Brick Buddy 2 is progressing slowly and still needs work.  The bigger issue will be parts availability.  Electronics parts have disappeared from the main stream suppliers and the secondary market can be 10 to 100 times more expensive.  That makes it cost prohibitive to produce right now.

Planetary Space Base made progress enough to continue to show it.

Train Tools did not get anywhere.  I have been working on a new turnout/signal control board.  My original design is rather old at this point and some of the parts are now unavailable.  So with the knowledge of the previous version, I have been working on a design that can be purchased.

On to 2022.

Brick Rebuild NES Set 71374

 I finally have finished all of my hot projects.  It is time to get back to this. This is the NES of set 71374.

This had been sitting on the corner (big mistake!) of my build table.  Then one day, I hit it with an elbow and the above picture is the result.  There was so much going on, that I decided to leave it where it landed.  This went on for many weeks.

After finishing all of my builds and with Space Port still in its carrying cases, the build table was finally clean.  I finally picked up the pieces and this picture above is what I had.  I actually had to do some disassembly to determine where the pieces went, as the picture below shows.  Fortunately the rotating screen did not get damaged other than a few cosmetic pieces.

After about 20 minutes I got to this point in the picture below, with the help of some coffee.  Again it was a combination of disassembling the dislodge "chunks" and then reassembly on to the main piece.

At this point it is mostly assembled into the rotating screen, the case and the front panel. 

Here is the TV assembled.  Missing two pieces, square brown tile and curved gray tile.  Also two extra pieces, 2X2 black brick and a 1X2 nougat tile.

Searching around the room and every corner I found the square brown tile and the curved gray tile.  I looked though the manual and could not find the 1X2 nougat tile.  This may have fallen down from other parts that I bought over the last year.  Every instance of the 2X2 black brick seemed to be installed as I once again went through the manual.  So again, I assume it fell on the floor at a different time.

 I made some changes to better lock the TV to the stand as shown here. The issues is the bottom of the TV and top of the stand are both socket sides, thus there is no inherent connection.

I moved the 3 1X8 Light Gray plates.  The two on the side now fit into the slots in the stand.  The one in the back is up against the stand.  Those three were part of the set.  I added the 2X6 brick as extra alignment.  Thus the TV cannot slide on the stand, but is not connected to the stand.

This picture shows the changes to the stand.  The 2X4 plate and two 1X6 stacked plates meet up with 2X6 brick I added.  Again there is no connection, this just forces a four sided friction fit.

The next two pictures show the connectors I built. First a rendering blow up.

And the one I built.

 This is how they are placed in the corner at the back.

Then a 2X3 plate and a 1X2 plate are placed on top to lock the TV to the stand. 

This is a minimal connection.  You could put these connectors in the front corners also to provide a better connection.  But doing so means they can be seen.  Since I did not have any parts in the stand color, I went with the back only.  

This will keep the TV from sliding of the stand easily.  Doing this before may have given me an opportunity to catch the TV/stand before it fell of the table top.  So this makes the TV and the stand more of a connected unit, but it will slide across a table.  

Happy Holidays!