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John,

I set aside a couple of hours yesterday and finally built the signal buffer kit. Haven't had time to test it over the entire layout but in preliminary  testing 3 locomotives responded well on different segments of the layout. I plan to add the pot and resistor modification and noticed the component layout is different on the kit PCB than the production unit PCB shown in the online picture of the modification. Is R5 the correct resistor to replace in the kit version PCB? Thanks for your help and all of your contribution to the Forum and to the hobby. 

All the component designations stayed the same between the SMT version and the thru-hole version, that was by design.  So, R5 is the correct resistor to remove on either version, the amplitude adjustment mod works exactly the same way for either.

All I did to do the kit version was take the SMT version and convert all the surface mount components to thru-hole.  For various reasons, the components aren't in the same locations on the PCB, but that doesn't affect what you're trying to do.

gunrunnerjohn posted:

This is intended to be a continuation of the original thread for the TMCC signal booster to avoid confusion. I was working with Dale to create the "production" version of the buffer.  That involved creating the PCB and building some units.  Sadly, Dale passed away before we really got started, so without his input and documentation, the project languished for some time until recently.  I enlisted the aid of another forum regular, PLCProf, to assist in recreating the schematic and getting to the point of confidence that we had a working design again.

Here's a recap of where I started after Dale's passing.

As some of you may know, I was working with Dale on this project, my end was to be creating the PCB and packaging once the design was proven.  Due to Dale's untimely passing, the project was stalled.  Since I never got to actually receive the final schematic, I did manage to round up the prototype.  I enlisted some aid in reverse engineering and testing the prototype and the project is moving forward.  We have reverse engineered the prototype and are making some tweaks.  I'm hoping to maybe have a prototype PCB at York next month, however timing may be tight, so that's only about 50/50 right now.  However, rest assured that it's coming soon.

I have what I believe is a completed schematic and I've done a board layout that should work with the enclosure I've selected.  I haven't received the boxes yet, so there could be changes, one of the delays I mentioned.  The "production" unit will have an off-the-shelf 24V power brick that is detachable.  The terminal strip you see on the side will be the "Euro" style, but my 3D library didn't have those.  Those terminals are where all the connections to the buffer are made.  The board projection with the TO-220 package will have a heatsink mounted to the two large holes and also be outside the box, this is to allow air circulation for cooling the buffer chip.  The white line on the board is where the enclosure wall will be, a slot allows the board projections. There is a power LED that projects through the top of the case, and also some signal level LED's that indicate a poor or missing base signal and also a "good" base signal.  Connections are also provided that output a DC level corresponding to the signal strength of the input base signal and the output buffered signal.

Discussions should continue in this thread.

Thank you John for your note.  Through another referall I am on your list.

The last of my parts are in, and I have commitments for a number of them.  I still have about about ten more parts sets for the buffer.  I am offering them assembled for the original price, or I also am offering a kit of parts as well.  Please contact me using my profile email address for more information.  Assembled versions will be BTO (Built To Order) as the mass produced ones are gone, and I'll be hand assembling and testing the few that are ordered.  Obviously, that will also take a bit more time as I'll be doing them on demand.

Dale will be missed. I started all of this with the first  signal booster that was built with vacuum tubes. Solved all of my signal problems. I immediately published all of the data for that device on this forum.   A few more were built by others with totally unusable TMCC railroads to solve their problems. Many people requested a solid state device instead of the vacuum tube model I was using. Converting it to solid state to make it smaller and less expensive was not something I was willing to undertake. Dale stepped in and took that task on. Thank you Dale.  I have seen the diagrams of his units and heard good things about its performance. Both I, and I am sure Dale would agree, that what we have done to solve the perplexing problem on troublesome TMCC railroads is a contribution to the hobby that we all enjoy so much and we and those carrying on the effort to make thing run smoother and better are good for all. 

Jim, you are certainly to be commended for your first version.  I know the NJ-HR used that for years until they cooked it trying to get just a little more "boost" out of it.   I am very sad that Dale wasn't around to see the logical conclusion to his efforts, he was gone way before his time!  One of the brightest guys I ever met, he had a knack for building practical solutions to vexing problems.

As users of the tube and solid-state buffers, the NJ hi-Railers are very thankful to all the contributors of these devices. With our 30' X 185' (~7,500' of track) layout, these buffers have made a tremendous improvement in the performance of TMCC!

Thanks again to all the contributors, 

Bob D 

NJ Hi-Railers

Electrical Team

 

If the power light doesn't come on, that's pretty basic!  Since you have a red light, you're getting power, I'd say the power LED is in backwards.

Top suspect is the output amplifier having shorts between the pins.  They are VERY close, and it's very easy to short them without knowing it happened.  Use an ohmmeter to check between adjacent pins and make sure none are shorted.

As far as the signal, lots of stuff could have affected the signal.  Do you have anything like a 'scope to look at what's happening in the circuit?

That probably didn't do it any good!   Send me an email with your address and I'll send you a replacement.  In looking at the circuit, I wouldn't expect that to cook anything else, but I could be wrong.  Actually, with the usage of that particular cap, I'm surprised it cooked, it actually has very little voltage across it in normal operation.  I'd actually expect the buffer to probably work, at least for some time, with that one in backwards.  I'd look around for any other component issues, for sure check C1 and C2 for proper orientation, they will greatly affect operation!

Specifically, note that the stripe on both of these faces the power jack.

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Folks, I've had several kits come back to me with issues to solve, and usually it ends up that they were soldered with what appears to be acid core solder.  THAT'S A GIANT NO-NO FOR ELECTRONICS!  You must use a noncorrosive flux, the standard is rosin core solder.  I use the 63/37 Kester Rosin Core solder for my electronic work.  Save the other stuff for plumbing!

I have a couple of the final sets that I've assembled and tested on the shelf if anyone is still looking for one of these.

That would have been a good idea, but I'm winding this down now, I have a handful of parts left for a few more units and I'm done.  When I get some spare time, I assemble one or two and put them on the shelf. 

I still have to come up with a nice package of documentation so going forward after my parts run out someone could duplicate the buffer, don't want the process to get lost.

I built a lot of Heathkit devices over the years. Everything from a color TV to stereo components to test equipment. I always remember the warning that Heathkit had on the 1 st page of the assembly manual. Kits returned for repair or troubleshooting that have been assembled with acid core solder or fluxes will be returned without repair and warranties are void. Use only rosin core electronic solder.  Heathkit even went as far as including a coil of solder they wanted you to use with the kits. 

John, the gerber files and components list would be great!! 

One item we have started doing is to use a socket for the eprom for easy swap, we have 3 of the kits left, and have secreted the unit under the layout so it can not be unplugged. The units we lost to electrical overload from the ac/dc plugs being swapped lead to this change.

sandysimon posted:

I am just reading this forum for the first time - my loss at being late to the party.  Is it still possible to get one of these?  Thanks!

I still have a few sets of parts, so I can still supply them.

Ron_S posted:

One item we have started doing is to use a socket for the eprom for easy swap, we have 3 of the kits left, and have secreted the unit under the layout so it can not be unplugged. The units we lost to electrical overload from the ac/dc plugs being swapped lead to this change.

Ron, what EPROM?  There are no programmable parts in the TMCC buffer.

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