01/09/05  

Voltage Regulation of lights:

Aristocraft puts 14v lights in their Heavyweights and run them directly off track power.  (A pretty standard setup)  The problem with this is if you want to run a Digital Controlled engine like the MTH Challenger which needs to operate at 18-24v, the lights would burn out quick and be way too bright at those voltages.  Since it was important to run the cars with the lights on with the Challenger, I had to figure out a way to fix this.  I could have:

 

 

*Update*  Some after the fact thoughts:  I have found that once I committed to running my engines under digital control, I found that I never run my engines now on variable track power so the benefits of voltage regulators such as what I made here are greatly minimized.  I think 99% of the people out there should just replace their bulbs with a 24v or 28v version and be done.  Much easier and cheaper.

 

 

 

How I built and installed the regulators:

 

Going with the 12v regulator had issues to overcome.  First, was the heat.  It would need a heat-sink to keep from overheating.  No problem, just slap on a small heat sink right?  WRONG.  With 24v input voltage, the regulator was dissipating so much heat the heat-sink would burn you to the touch.  More was needed to cool it.  I went with ever bigger heat-sinks to the point where the size became impractical.  I then decided to try a fan on top of a heat-sink.  Bingo.  After a bit of searching the net, I finally found a fan small enough to fit in the available spaces in the cars.  In addition, I found an item I could use to make miniature heat-sinks to go under the fans.  Combined with a 1 amp 12v voltage regulator and bridge rectifier, I was able to make what I was looking for. 

To make the little "package" above, I used a Dremel with a cutting-disk to cut-out the exact sized heat-sink I needed out of a larger heat-sink case.  Next I Drilled holes for bolts and bolted the fan and voltage regulator to the heat-sink with #2 stainless steel bolts and nuts (from Lowes).

Next I soldered wires to connect the bridge rectifier to the voltage regulator and extra wires to connect to the Heavyweight's internal wiring. 

I chose to tap the wires that run up to the lights on one side of the car as the place to install the regulation package.  See the steps below to disassemble the end of the car.  (Note: When sliding the end of the car up, use both hands and be careful.)

Once you have end off, you will see the two wires that supply the overhead lights power.  Cut the wires at the half-way point and strip the ends to expose the wires.  Then either solder or use solderless joiners (as is pictured below) to connect the regulation package to the car.  The wires from the floor need to go to the inputs of the bridge rectifier.  The leads from the roof, need to be connected to the positive and negative outputs of the regulator.  To attach the package to the floor, use some sort of double-sided adhesive.  (I used super-strength outdoor mounting tape by 3M which can be found at Wal-Mart.)

And when you're done, your lights will be regulated...

The Diner car was different from the rest as it has LED lights on the little tables inside that only light up at the higher voltages (16-24v). So, in order to get the LEDs to light up, they need to run off direct track power.  To do this, the roof needs to be taken off first.  Take the end of the car off as noted above.  Then unscrew the four screws holding the roof on.  These can be found in the area you just gained access to by removing the car end.  (These two screws can also be accessed with the end of the car on by using a long screw driver through the holes in the bottom of the car.)  Next you will likely need to pry the tab (that is connected to the roof and is inside the car) holding the center of the roof on with some sort of long screw driver.  (I wrapped a jeweler's screwdriver onto the end of a long screwdriver with electrical tape.)  While bending the tab back, carefully pry the roof off. (This is very difficult and tricky.)  Once off, de-solder the single power lead along the roof top that goes to the table lights and curl it back.  Then solder another long wire lead to the connector and run the new wire along the roof top to the other end.  This wire lead will be used to tap into the track power connection and bypass the voltage regulator altogether.  Put the roof back on.

Here are pictures testing the table lights by jumping the connectors.

Repeat the process noted above to install the voltage regulation package with the exception of the extra lead wire that needs to be connected to the track power connector.  Viola!  Regulated lights AND table LEDs that are brightly lit.  Looks sharp!

The Observation car required some extra effort in order for the "package" to not be visible.  Same install process, just stuck it against the top of the car and insulated the wires to protect against an accidental short.  Also, instead of solderless connectors along the sides, I soldered the wires and used heat-shrink tubing to cover the connections. 

 

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