Design of a $10-20 DCS-TIU Port Tester Tool?

Adrian! posted:

gunrunnerjohn posted:

Poorly.  The signal strength in the locomotives simply measures how many good packets vs bad packets it gets for a test stream.  Depending on the circumstances, it could be getting all good with low voltage from the TIU.  Also, as we all know, a good TIU with bad wiring/track layout will yield bad results.

This is a tool to test the TIU independently.

Actually, since we’ve been talking about lengths.... the MTH signal test also uses a very short test packet like the length of a speed command (about 500us), so it’s skewed to be very optimistic and doesn’t inform the situation for longer commands like adding engines or app reads

https://ogrforum.ogaugerr.com/...-signal-stregth-test

I think I knew this before I asked?

Again, thank you for the time to explain things.

GRJ, I think I am beginning to see what 'Feature Creep' really means. 

Adrian, Thank you for the earlier reply and formula.

rtr12 posted:

GRJ, I think I am beginning to see what 'Feature Creep' really means. 

Fighting feature creep is very hard for us designers!

True John, but it sure sells cars!  Remember when, if checking for a used car, you looked for "R&H: on the windshield.

For that matter, why have we gone from conventional to DCS?????

I'm beginning to understand that now! Was also thinking about some of GRJ's projects with Stan's help! 

Some great ideas do come from that, just have to know when to quit I guess? The really difficult part!

Well Adrian, as if you are bored with nothing better to do, could you look at the signal packet for a large consist of engines and determine just how much longer the packets are for them vs. a single engine?

 There were times I could get great response from running a single engine around the track. Then it would seem like "all hell broke loose" when I built a big train. MTH posted that running a big consist took more info to communicate with the consist. I believe they said each engine has to respond back correctly to satisfy the command?

Don't quote me exactly on this stuff as my memory is not working fully right now...

Seems it was a bit more parts than I imagined to do the multiple level indicator.   I did put them all on one side, the board is 1.1" x 2".  Maybe this was too much "feature creep".

Maybe using smaller LEDs would help, possibly 3mm? 

Gee, you already have it redesigned, drawn up and ready to go with PCB designed. While I have only loaded Diptrace and found the parts section...and that was using Adrian's schematic (no redesign) and it's not yet entered into Diptrace. But, at least it's a start! 

Yogi Berra out driving with a friend with a specific destination in mind... The friend said I think we are lost, Yogi replied, yea, but we're making good time! (That would be me and Diptrace)

The board is already small at 1.1 x 2, and I happened to have a 5mm LED footprint handy...

Diptrace is great, but as for any such tool, there is a learning curve.  You're going to find out the hardest part is finding parts you don't have in the library and creating new ones.   I've used it for perhaps a couple dozen boards so far, so I've built a library of many of my commonly used parts.  To get the 3D views, you also have to hack the 3D representations of parts, sometimes I grab a totally different part 3D view to "build" the part I need.

Thanks for the encouragement! I hit a snag already, with the CD74HC123. They didn't have one. I did find the part search though. Next step is, as you say, trying to figure out the library stuff to modify the existing generic 16 dip I found to match what I want. Might as well start learning now I guess. I can see this will be taking me a while. Parts in Diptrace are harder to find than searching through Digikey! 

I was kidding about the LEDs, but I will keep the size you had in mind. One goof I did already was to order a 9v battery holder...sounded good at the time of order. maybe now not so much. Diptrace doesn't seem to have those either... 

If you want to whip one out for everyone else, please feel free. I will probably be testing everyone's patience while learning to create mine. I am only doing the simple one that Adrian first posted. I'm still way too green for any feature creep! I do have what I think is a valid parts list from Digikey which anyone that wants it is welcome to. I can post if anyone is interested.

You didn't look hard enough in the DIPTRACE libraries.  If you search for 74123, you'll find the part.  The SN74123N is the one to pick.  The HC parts are a just high speed CMOS, but they have the same pinouts as the TTL parts.

Part of the magic of parts is knowing that the different technologies are all the same pinouts as a rule.  When you're looking for something like the 74XXnnn part, for instance, search on the 74nnn part instead and you're more likely to find it.  Sometimes, especially for surface mount, the proper footprint isn't available.  Then you can simply find a part with the proper footprint and graft the two together to create the necessary part.  I don't usually have to create a footprint, but for certain parts I have had to do that.  Once you do a few, it gets pretty easy.

Thanks, that is a very good tip on the 74xxx parts. I knew there were different ones, but didn't know about forgetting the letter designations and just using the numbers. Wasn't sure they were all the same either? That really helps a lot! All I found was a bare DIP 16 socket, didn't have any of the designations on it like Adrian's drawing.

I watched the Diptrace tutorials last night, but I was tired and. Probably need a mulligan on the tutorials. They went through things pretty fast too.  

I am off to hunt the SN74123N! 

gunrunnerjohn posted:

Seems it was a bit more parts than I imagined to do the multiple level indicator.   I did put them all on one side, the board is 1.1" x 2".  Maybe this was too much "feature creep".

Hi John: What software did you use to draw the electrical schematic and what software did you use for the 3-D Drawing?

Thanks: Gary

Gary, I use DipTrace for the PCB work, and it includes the 3D feature.

rtr12 posted:

Thanks, that is a very good tip on the 74xxx parts. I knew there were different ones, but didn't know about forgetting the letter designations and just using the numbers. Wasn't sure they were all the same either? That really helps a lot! All I found was a bare DIP 16 socket, didn't have any of the designations on it like Adrian's drawing.

I watched the Diptrace tutorials last night, but I was tired and. Probably need a mulligan on the tutorials. They went through things pretty fast too.  

I am off to hunt the SN74123N! 

Another clue is sometimes it helps to leave off everything but a few numbers from the part, that may find parts you didn't find other ways.  Sometimes it also returns tons of other stuff, that's part of the fun.   Try 123N for instance, it returns twelve 123 single shot parts of various logic families.

Don't you mean part of the struggle?   Actually, it is kind of fun, but I have a lot left to learn. Thanks for another great tip here! I will fiddle with both and see what happens. I did find the parts search box thing or whatever that is...

P.S. - Don't go anywhere! 

Thanks John:

Is this it....... ?    •    YouTube has several tutorials.

Gary

That's it Gary.  I tried several packages, and IMO this one had the nicest interface, much more intuitive than the others.

RTR12, Face it we can’t concentrate on anything after supper!  Only electric sages like John and young supermen like Adrien can stand up to the challenge!!  I think I’ll take a nap now.    zzzzzzzz

Just for you Mark.