Working DPU marker lights and more...

ram53 Nov 19, 2012

  1. ram53

    ram53 TrainBoard Member

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    I've been working on this FVM CN GEVO on and off for a few weeks. Notwithstanding it's still not done, I'd like to show some of the modifications I've made. I rebuilt the front and rear ends with 5 step instead of 6 step platforms, rebuilt CN style anticlimbers and repositioned stanchions and ditchlights, requiring all-new materials. The ditch lights are Kaslo Shops resin castings with 0402 LEDs in them. What I think is kind of cool is the DPU marker light set on top of the left ditchlight, as per proto. It is an 0603 LED, tinted red as I didn't have a red one, with a piece of brass from a BLMA antenna stand with a hole in it cut to fit and glued to the LED face after painting. The sides and back of the LED are blacked off with black lacquer to cut stray light. The leads go into the engine along with the ditchlight leads to an SDN144K1E sound decoder. The DPU light is wired to the F0(R) reverse pad, so the red light comes on when the engine is in reverse. That seemed the easiest way to control it.

    Here's the front end, lights off:
    [​IMG]

    Front lights on:
    [​IMG]

    DPU light on (camera doesn't capture the red very well because of the brightness):
    [​IMG]

    For the sound install, the SDN144K1E doesn't "fit" in the GEVO if you use the motor tabs, so I just wired the motor leads to the decoder. I saw a demo on Model Railroad Hobbyist website about speakers, in which it was shown that the best enclosure for a speaker is actually no enclosure per se, but a means to isolate the front and rear of the speaker cone, so the destructive interference that comes without this isolation doesn't get to happen. He showed a bare speaker (really bad sound), a speaker in a sealed enclosure (OK sound), and the same speaker placed in the middle of a small sheet of plastic about 6" square (best sound)! I figured that if I milled out the tank all the way through to the motor, then filled the frame half gaps around the back of the speaker with a "gasket" of styrene, and sealed the down-firing side (speaker firing down to the track) in the milled hole, I could get a better sound than trying to make a sealed enclosure, which in N scale diesels is practically impossible under any circumstances.

    These are the frame halves after milling, with a smaller opening into the motor compartment and a larger opening at the tank bottom, and white styrene gaskets sealing the milled cavity. This way the whole engine cavity truly acts as a large enclosure, and the out of phase sounds produced at the front and back of the speaker are attenuated by the distance they have to travel before they meet, like the example of the great sounding speaker placed in the middle of a sheet of plastic .
    P1080516.JPG

    I'm trying to upload a sound clip of the loco in action, showing the lights and sound. I had an HO Intermountain GEVO with Tsunami sound, and while the HO sound is better, it's not remarkably better, and some of that is the 16bit Tsunami vs the 8bit Digitrax. A half-inch speaker can only do so much after all, but this is the best N diesel sound I've come up with yet. It's actually too loud and has to be turned down-N scale sound has to be scaled down to seem realistic, I believe. Hopefully I can post the video clip in a few minutes.
     
  2. ram53

    ram53 TrainBoard Member

    293
    17
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    This is the decoder and sound install from the inside, the 3-pack of 100 uF Digikey tantalum caps are on the back of the frame. The loco runs very smoothly without stalls/restarts.
    P1080527.JPG

    Here's the video clip, for what it's worth. I'm just flashing the lights at the end to highlight the forward/reverse lighting effects.

    [video]http://s965.photobucket.com/albums/ae131/drinfidel/?action=view&current=P1080521.mp4[/video]
     

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