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I've finally gotten back to considering the build of the TMCC buffer.  I originally started with a thru-hole design, as I expected to build a handful of them.  The list has mushroomed to 82 potential customers.  Even if some drop out, that's a LOT of hand assembly!  That being the case, I'm converting it to a mostly surface mount design so I can get them factory assembled and only have to stuff a handful of parts on the board before I assemble and test them.  Although the turn-around is a few weeks, I suspect that it'll be faster than if I had to do all the work to assemble them!

Here's what the new board looks like.  The schematic for it is identical to the existing thru-hole design, the layout generally follows the same pattern, but some parts have moved.  I expect the actual performance will be exactly the same as the old prototypes.

Sample boards are on order to hand build one of the SMT design to test it before I commit to a larger build.

I also build some simple drilling jigs so that I could prep the enclosures and get the holes in the right place.  After sending pieces of a couple of the little plastic boxes flying, I perfected the process.

Stay tuned, things are moving along.


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I thought it might be nice to post the preliminary documentation for the TMCC buffer since I'm getting closer to turning it loose.  This will give you a good idea of what you'd be getting as well as the complexity (or lack of complexity) to connect and use the buffer.

DM TMCC Buffer Documentation.pdf

Obviously, any questions or comments are welcome.


Dale Manquen did all the heavy lifting on this one, he designed it and built a couple of prototypes.  I was working with him and my end was to be creating a product that we could duplicate in some quantity.  Sadly, he was gone before we could get it into production, but I decided to forge ahead anyway and complete what we started.  What you see is Dale's smarts and my limited skills at laying out boards and cutting holes in plastic cases.

Jan posted:

Is there any criteria or rules-of-thumb that say one should add a signal booster tp a layout?  For example, layout overall dimensions, total track footage, length of longest loop, star wiring, number of power supplies, etc.

The only "rule of thumb" is if you're having signal issues and have tried the conventional fixes of adding ground wires, etc.

MartyE posted:

Does this affect both the track and earth ground portions of the signal?

Well, by definition it would affect both sides of the signal as the signal is simply the voltage differential between the earth ground and track signal.  If you check the DM TMCC Buffer Documentation.pdf document I posted previously, you will find a schematic of the buffer circuitry.  You can see that the boosted signal comes directly off the output buffer, and earth ground is tied to a ground reference point internally.  It may not be obvious regarding the ground as it's connected to a virtual ground point that is centered on the 24VDC input power.

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