Feb 11, 2008

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.

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