Still working on decoders!

I'm still working on those diesel rebuilds, but they're nearly done now. After figuring out that the headlight LEDs could be wired back-to-back, I'm on to the next phase. The LEDs look great; I've got one each for the upper / lower headlights, and only one comes on depending on which direction the loco is facing on the track. I ended up using 1.2k resistors, and the brightness looks about right to me. Track voltage w/ my Keller Onboard system is 14.5v DC. I mounted the LEDs by soldering a pair back-to-back w/ the right spacing (to match the headlights on the shell), filing the end of each LED flat, and super-gluing them to the rear of the headlight lens.

With the headlights done at last, I moved on to connecting the A- and B-units, installing the Keller decoders (called throttles actually) in the B-units, and routing some small stranded wires between the two units. On the F units, I mounted Kadee #47s (I think - short shank, underset, metal) couplers, and was able to run a wire thru each of the ear holes on the Kadee boxes. I used shrink-tubing to attach a second wire to each of these, and thus got four wires routed alongside the coupler boxes, looking almost like MU cables. Two wires carry motor power from the decoder in the B-unit, and two carry track power to the decoder.

What's left? Final details on the shells, and (probably later on ) weathering. Air brushing is another long-dormant skill, so I'll have to get back up to speed there as well. But with 4 new Keller-equipped locos, I'll probably focus next on getting Keller installed on the layout, so I can use these new guys.

I've also finally posted a newer version of the layout trackplan. I had created a design in Empire Express for another friend, and a fringe benefit of that is that I really learned how to dress up the drawing within that software package. What do you think?

Keller OnBoard and headlights

So, here I am, sitting at home and quietly finishing up super-detailing my 7 locomotive shells that I've been working on the past few weeks. Yesterday I finished up the last of the tiny decals I like to add - fuel & water labels, warnings, other little tidbits. I'm been using using diesel decals sets from Rail Graphics, purchased quite a few years ago - the last time I did this work, about 1991 believe it or not.

I also re-numbered one of the Athearn PA units (why must all PA-1 units out there be numbered 6009 !?), and finished up add numbers to the number boards of my Athearn PA and a pair of F7As. Not fun, but I did enjoy learning how to do it.

I suppose I should photograph these models when they're complete so you can see what I've been doing.

Anyway, back to Keller Onboard... I switch my focus to electronics, starting with the Lifelike Proto2000 PA / PB pair, which I thought would be the easiest. I had purchased a number of the 8-pin 2x4 NMRA plugs a while back, and soldered up just the track & motor connections on one of them, and plugged it into the NMRA plug on the PA to test it. The motor ran nicely w/ Keller, but no lights.

Of course - I hadn't jumpered the headlight connections. But, after some more experimenting, I found that the two headlight circuits are both polarity-sensitive (pins 6-7 for the oscillating headlight, and 3-7 for the lower headlight & numberboards). The oscillating headlight varies two circuits, to light two filaments inside one bulb to get the oscillating effect - about +/- 5v going to the bulb, but working on with pin 7 positive and 6 negative (I think - I might have it backwards). The lower headlight is just 1.5v, and again works w/ only one polarity.

With DCC, the decoder would provide the correct voltage and power to control these separately, and with normal DC both work but only when the locomotive's moving forward. The problem for me is that the rails will have a set DC polarity, regardless of which way the locomotive is moving. Thus, if the locomotive is on the rails facing west the headlights would work, but facing east they'd be off, regardless of whether it was moving or not.

I could replace both with my golden-white LEDs from NCE, and probably will I guess. I like the oscillating effect, but it uses the locomotives electronics and needs that certain polarity. I could light that bulb directly from track power (skip the electronics), and use a resistor to get down to 5v or so. No oscillating, but easier wiring. Or, I could replace both bulbs with the LEDs wired back-to-back, so that one LED would work for each direction the loco's facing.

I did finally figure out how to address the reverse-voltage problem... those LEDs don't like reverse voltage, and the Keller Onboard system puts 14.5v on the tracks. Turns out that with the LEDs back-to-back, one will light and the other won't, and the dark LED is protected from the reverse voltage by the current running thru the LED that does light. Assuming a current of 30 mA, I'll use a 3660 ohm resistor on one side of the two wires running to the LEDs. This is what I plan to use w/ the other locos.

What to do w/ the LifeLike unit? Not sure yet... I'm leaning now toward just lighting the two bulbs directly with appropriate resistors, if I can guess what their current draw is.

In a detailing mood...

I've been staying out of the basement lately, and have gotten into a super-detailing mood with some of my diesel locos. It started because I'd reached a point in layout construction where I wanted to install my command-control system (an old Keller OnBoard system). I've started working on that, but got to the point where I needed to install decoders (Keller calls them throttles) in some locos.

Not wanting to tackle the steamers yet, I figured I'd ease back into this by starting with some diesels (remember - my RGS is set in the late 1950s, and the SP has purchased rights or perhaps the entire road, so SP diesels will be showing up sometimes).

Keller likes low-amperage motors, and needs really great pickup in order to work smoothly. On my old layout, I'd converted a pair of GP35s and a pair of SW1200s, remotoring with Sagami can motors (I like the 2032 best), and wiring the units together in pairs, using all 4 trucks for pickups. I also replaced all the old Athearn wheels with NWSL wheels, again, for better pickup (the NWSL wheels are nickel-silver, and much better than the old style Athearn sintered iron or steel wheels).

Those engines will run great, and I next remotored my first Athearn loco, an F7 I received in the late 1970s I suppose. Then, I started on converting a pair of Athearn SP Daylight PA-1s. That project was put on hold about 14 years ago when kids came along, and have sat (in pieces) since then.

Fast-forward to today. I pulled out the ancient F7, and (for practice mostly) got that running again, It also has a Sagami 2032 can motor, hard wiring to both sides of the trucks, new wheels, etc. It needed a drive shaft repaired, and now runs like a top. With a little confidence now, I finished remotoring both PA-1s and two more F7-As, and installed new wheels and trucks on a pair of F7-Bs as well.

So now I'm ready to install the Keller throttles, right? Well, I also have a Proto2k PA-1 that's gorgeous, and really those Athearn shells could use some details. I'm going to use LEDs for the headlights, which means the shells will be hard-wired to the frames, which means any shell detailing is best done now.

Off I went to the hobby shop, and returned with MV lens, handrails, etc. I can't tell you how much fun it was to sit at the workbench installing lift rings, grab irons, and what not. It's been YEARS since I'd done anything like that, and it was very fun to return to. Plus, the basement is still cold and the workbench is upstairs in the comfy warm study. I'm sick of winter, and the warm study is inviting.

I'm still finishing up the super-detailing, and even added a backup light and cab room grabs to the Proto2k unit. I've got the LEDs ready, and will someday get the Keller throttles installed. That's gotta be last, because as soon as they're ready, I'll probably jump back down to the basement so I can get the Keller system installed, and then I might never return to the workbench and finish the detailing work!

Photos are here, and an update

I haven't posted many photos of late, but all the existing layout photos are still online - they're here in the blog. Just scroll down, and go to the older posts when you reach the end.

In other news, I've been monkeying around with the Keller OnBoard system, deciding exactly how to implement it. I have found that Keller produced a number of different versions of the throttles (decoders to you DCC folk), and mixers (power boosters). Here's some details of what I've discovered, in case anyone is interested:

The most recent mixer seems to have one huge heat sink, uses a red circuit board, and has options for digital components. Keller was one of a couple proposals for creating a digital command-control system (which eventually became DCC), but his design wasn't accepted. However, he did do a bunch of work creating a digital version of the OnBoard system, one that would work with both the analog and digital throttles at the same time. I'm not sure if he ever got that working, but looking at the extra space and layouts on the mixer, it was certainly in the planning stages.

Early mixers used blue circuit boards, the earliest having one heat sink, then versions with two heat sinks (still blue).

As to throttles (decoders), the T1 was eventually shrunken down to 0.7" long. The most recent version of it has an IC in a socket (as opposed to direct-solder), so between the size and the IC, I think I can now identify the most recent versions of the T1s. All of the smaller T1 versions also seemed to have better protection against overloads and overheating, and some type of H-bridge power output section. I have a number of T1s labeled both A and H, so I've been trying to figure out what the H meant; I think it referred to this newer output stage.

And finally, all of the newer T1s have a double row of solder points in the middle, so you could cut the unit in two (for tight fits), and run jumper wires between the 5 sets of solder points.

There was also a smaller T 1/2 throttle, but once Keller was able to shrink the T1, he discontinued the T 1/2 design.


Keller used 1/4" stereo jacks for his keypad plug-ins. I don't like those much, as they are kinda hard to remove and the strain is tough on the fascia and on the jack itself. I replaced all mine (on an older layout) with all-metal jacks, but the pulling is still not that great. Also, they short briefly when being inserted or removed, causing a warning beep from the mixer. I thought about using RJ45 connectors, as some DCC systems use, but those are kinda fragile.

I've settled on using 3-pin XLR jacks on this layout, the same as used for microphones (I do a bunch of theatre and concert lighting on the side, and we use a lot of XLRs). I haven't installed these yet, the jacks themselves are metal, they have a locking pin, and in genenral seem very robust. For the keypad, I'm using female black jacks, and for the layout / fascia I'm using male jacks.

I'll let you know how it works out.

1156 done at last

This weekend I finally finished installing the last of the 1156 lamps, covering all the blocks and other track sections on the layout. It's always a bit fussy soldering these lamps in place, so I'm glad to move on to something else now.

I've been running the layout's mainline a lot, now that it's complete. I've had the test train running forwards and backwards around the entire layout, at speed, and so far all looks good. I even reversed the loco / caboose so the engine was pushing the train from the other end, then ran that both forwards and backwards... still running ok.

Probably the next step is to begin working on the 'real' control system - my old Keller OnBoard. I've decided that I really need two 'mixers' (like DCC boosters), so I'll have to modify the main power bus a little to split it, and then build transition track sections (some gaps and a couple more 1156 lamps), as using multiple Keller mixers is a little different than using multiple DCC boosters.