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Welcome to My HO Model Railroad Blog

February 15, 2017 Another Project Mod

If you follow my blog you know I'm never really finished with any of my projects.  Ten minutes after I "finish" a project I see where it could be improved or done a different way, maybe more efficient or something I missed.

This post is about mods needed to make my Arduino micro controllers compatible and adapt them to my last project, my Arduino 8 slot card shelf.  The Arduinos need a rear connector to adapt them to the card shelf, a right angle connector will make it easy to connect to the cards.

The Random Lighting Controllers will be the easiest to convert only needing a single row 20 pin 90° right angle male connector.   The UNO 20 pin female connector consists of two connectors, a 16 pin for the structure lighting and a separate 4 pin for Arduino power.  Pins 1 to 14 will be the high current outputs or in this case negative/ground switching, pins 15 & 16 will be for power to the structures.  The remaining pins will be for Arduino power.  Because I operate my 12 volt incandescent structure lighting at 8½ volts, one pin will be used for the isolated high current input a second pin for high current common or ground.  My Random Light Arduino controllers will operate from the 5 volt DC to DC converters connected to the board at the USB 5 volt board connection.  The 5 volts will also power the TTL circuits in the seven channel driver chips.

I simplified the wiring by using two separate female connectors to mate up to the male 20 pin angle connector.  One with 16 pins that will connect directly to the structure and a 4 pin for input power in to the Arduino.  That will eliminate the need for a secondary terminal block.  

The Arduino MEGA mods will be a slightly harder task to adapt to the card shelf.  At this time my Arduino MEGA is using dual expansion shields (boards) and each board will need a 40 pin dual row 90° right angle male connector.  My Arduino signal controller uses 68 pins to control 16 signal blocks plus power,  That will require a rebuild of both expansion boards.  This mod will also allow for any DC voltage up to 50 volts @ 500ma to be switched by the controller by using separate pins for power.  The Arduino MEGA power will be the same as the UNOs operating from the 5 volt source.

After a lot of thought and planning I decided to mount the DC to DC convertors to the top of the card shelf.  I need easy access to adjust the current and voltage adjustments and as I was planning to use a small fan to remove heat from the compartment, this arrangement will work out much better. 

Now I will have easy access to the Arduinos and the DC to DC converters.


The DC to DC  converters will be used to convert 12 volts to 1.4 volts for the 1½ volt micro bulbs used in my vehicles, 5 volts for the Arduinos and other miscellaneous electronic devices and 8½ volts for structure and street lighting.  The DC to DC converters will easily handle 8 amps each, with the help of forced air cooling they can supply up to 12 amps each.  My 12 volt power is a 30 amp switching power supply, very efficient and small, almost no heat from switching power supplies. 

A secondary venture in this mod will be to remove the on-board LED indicators, once the Arduino is up and working, the indicators are not needed and can't be seen when the Arduino in in the card shelf.  An external test plug with LEDs can be plugged into the test connector for testing if needed. 

 These are the components for my Random Lighting Controller.  The Arduino connectors come in 40 pin Breakable strips.  The 40 pin male connector needs to be cut with wire cutters to fit the Arduino UNO female connectors.


The Arduino Expansion Shield circuit board comes without connectors so I stock single row 40 pin Male and Female as well as a 90° angle Male connectors.  I also stock the dual row 2x40 pin (80 pins).

Because my structures were built many years ago using 12 volt Grain of Wheat incandescent bulbs my controller will need high current outputs.  The Arduino outputs are limited to 20 ma.  I use TD62304AP seven channel driver chips with 500 ma outputs per channel.  The driver chips have 16 pins so my expansion board will have two 16 pin IC sockets to accommodate the drivers.

I use a male 20 pin 90° angle connector on the rear of the board for power in to the board as well as the outputs to the structure lighting.

The driver chips have switched low outputs with 50 volt capacity.  The 20 pin female connector actually be two connectors, a 4 pin for power in and a 16 pin for the structure power.

The 4 pin connector will use two pins for Arduino power and two pins for structure lighting power. 

The 16 pin connector will use two pins for structure power out, the remaining 14 pins will be used for switched low outputs to the 12 volt bulbs.   

I have installed the Arduino shelf and the DC to DC converters in my control panel frame.


The far left converter is set to 1.45 volts to power the micro bulb headlights in my 80 plus vehicles.

The center converter supplies 5 volts for powering Arduinos and other solid state controllers.  The far right converter is set to 8.5 volts and it will power building/structure lighting and street lights.  The converter are powered by a 12 volt 30 amp switching power supply.

The two Arduino UNOs are programmed as Random Light Controllers, the UNO on the left powers Susie's Mansion and the one on the right powers Doug's "Psycho House".

I've been working on a camera car to be either pushed or pulled by one of my locomotives.  It will be integrated into my control panel in the Arduino portion.  I will be using an Arduino Uno as a wireless Blue Tooth remote servo controller.  The MD91S Camcorder will be mounted on a depressed center flatcar.  The servo will rotate the camera 180° via Blue Tooth.

This is my proposed Arduino panel layout.



I'm planning on using a 7" Tablet as a viewfinder with WiFi between the Tablet and the MD91S Camcorder.  The MD81S will function as a WiFI camera as well as a camcorder with a capacity of 60 minutes of AVI recording.



Drawing Updated April 1, 2017

The drawing above shows my camera car plan.  The camcorder is self contained with a 32Gb Micro SD memory chip and Lithium battery.  I will use track power for the Arduino Nano, Blue Tooth and servo power.  The flatcar has all wheel power pickup.

My new Arduino card shelf is in and working as planned. 
 

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