I’m embarking on my first Dcc installation as part of my sw1500 ktibash project. I’ve read lots and lots of posts here and elsewhere about decoder, light, and speaker installations. I’ve got several questions as a result, and I’m hoping I can get them answered before the glue and solder and drilling gets too far along.
The context is: an sw1500 kitbashed from an Atlas mp15dc, with the drive utilizing the gearboxes and motor from an Atlas sw8/9/1200 chassis. It’s a drop-in fit as the truck and motor mounts are the same for both types of Atlas switchers, and the sw1500 and sw8/9 share the same bolster spacing. So I would presume that motor amp draw and performance would be familiar to those here.
I’ll start with some pictures to show how I’ve got things arranged.
Decoder is a Loksound L Select. Speaker is Tang Band 1931 - yup that’s right. Tabs removed, material removed from both sides of the speaker, plus from the engineer’s side of the shell (accounting for the hand brake recess on the left side). I’ll post about this on the Tang Band thread. But it fits, and I didn’t breach the speaker enclosure. Life would be much simpler if I went with the 1925 module here, but no guts no glory as they say. I hope the 1931 sounds awesome.
Intended lighting includes numberboard over the cab, front and rear headlights, and left and right ground lights under the cab. Ditch lights are a remote possibility, but I haven’t nailed down an era yet for this model, so I may or may not need them. The switchers do not appear to have walkway lights at the bottom of the hood ends, and most of the SP units that I’m considering do not appear to have step lights either. I do know that the era I will be modeling will be post removal of gyralights and blanking of class lights, so I don’t need those, and I don’t need cab lights or gauge lighting either. I suppose the full SP light package would be cool, but it doesn’t really do much for me, so I’ll pass on that opportunity.
The decoder and speaker will sit on a styrene shelf. The shelf will have a “beam” running the length of each side, plus blocking, to prevent sag. The beam is .125" x .250" Evergreen tubing, so I can use if as a conduit to route wires through to avoid entanglement with the flywheels or any other moving parts. There will be an additional pair of styrene tubes under the shelf for conduit, as room allows.
I think that should describe the arrangements well enough. On to the questions.
What wire gauges should I use? I have the impression I might use three different sizes for track power and motor leads (24 gauge?) , speaker (30?), and lights (magnet wire?), all stranded. Can I just use something like a Digitrax harness, which I think is all 30 gauge, or do I need to use something different.
Should any of the wires be twisted, is it required anywhere, or is it something that should be avoided.
I see where Bob used what I presume are nylon screws to mount the decoder motherboard. Is this required if mounting to styrene? I presume this is for electrical isolation.
The Loksound motherboard appears to have the solder pads already primed with solder on the bottom side of the board. In a picture in one of the trheads here, it looked to me like Bob had soldered to the pads on the top side of the board instead. Is there a preference? Does it matter which side is used?
At a minimum, I would like to have the headlight leads connected with plugs or screw terminals, located underneath the exhaust manifold hood piece, between the decoder and speaker. And possibly the leads from the trucks as well. However, I don’t have a lot of space left between the decoder and speaker. So I would be interested in the smallest plug or terminal block, that would be reasonable to use. I can gain some space underneath the decoder if I elevate it from the shelf with some spacers, so that’s a possibility. But I can’t move the speaker forward as I need clearance for the radiator fan enclosure, and it would cover the screw positions where the board will be attached to the two existing lugs on the frame. I can’t move the decoder back as it is essentially up against the position of the cab wall now.
Lastly, I could use some suggestions on led and resistor specs for the lighting. I’m planning on reusing the existing Atlas numberboard light tube, in cut down fashion, for the headlights. I will be fabricating or printing a new numberboard housing for over the cab, and I will probably attempt something similar to Bob’s numberboard and ground light installations on his gp9. What I’m not sure about is which led’s to use. I see reference to something like “0603” led’s. Is this a size specification? Is there a color temperature which is best? Do all led’s require a resistor? Should I stick to Cree products?
Any specific information, suggestions, tips, admonishments, or other commentary would be greatly appreciated. As noted, I’ve done a lot of reading already, but often I find content that is based on HO rather than O scale installations. I’ve also spent a lot of time getting lost on the Digikey and Mouser websites. Those can be a bit overwhelming if you’re not sure what you are looking for already .