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Sunday, January 31, 2010

Birney Project ~ Installing the Decoder

"You've got too many damn lights in that thing!" George Huckaby.

I may have blown out all my lights, but the Southern California Traction Club has blown out entire decoders trying to get these things to work properly in trolleys running under live overhead! As a grateful benefactor of the trials and tribulations that the SCTC went through, I drew the following schematic based on the findings of the club (clicky to make biggy) :

This schematic illustrates how the TCS M1 decoder is to be wired in my model of SDERy Birney #301. The model has 10 (yes 10!) incandescent light bulbs in it, five of which would be lit at any one time (If I had to do it again, I would rather use LEDs in conjunction with fiber optics). The schematic also includes the necessary resistor that was so agonizingly missed the first time. I have the choice of having one 1 watt 100 ohm resistor* on the white wire and another on the yellow wire. Or one big 2 watt 100 ohm resistor* on the blue wire. Considering how big the resistors are (they are bigger than the decoder!) and how hot they get (and they get hot!), I decided to go with the one big resistor. BUT! That means not all the lights can be lit at the same time! Or else "poof"! Out go the lights yet again! That's a disaster waiting to happen, I'm going to have to be damn careful. Yes sir, Damn careful.
* Note: The value of the resistors were determined by some of the club members using wizardry and gadgetry that I'm not familiar with.
Bonus! Check out the March 2010 issue of Model Railroader for a resistor selector device on page 26.

First, the decoder is mounted to a piece of 3M 4011 Double-sided Mounting Tape, which in turn is mounted to the ceiling of the model.


Then comes the surgery. Two wires from 10 bulbs = 20 wires, plus 7 from the decoder, plus two from the motor, and two from the connector. Let's see, that's... 31 wires that all have to make specific connections with each other and the resistor, all in an itty bitty living space!


In this photo, we're looking through the cutout in the floor to the cutout in the subroof. I'm trying to keep the decoder (which also gets hot) as far away from the hot resistor as possible. So the decoder(right) is mounted to the roof through the subroof cutout. On the left side of the cutout I mounted a weight (simply for better running). The resistor (left) is glued half on the subroof and half on the weight. Hopefully this will help dissipate all that heat. There is officially no more room for anything else in this model!

Everything tucked up into the ceiling pretty nicely, preserving the seethroughableness of the car, even at this low angle. Good enough for me. Next stop will be the programing track to program the decoder. Then I'll officially take my place among the ranks of DCC-ers. Yes sir! I'm getting with the program!

Dandy