TMCC/Legacy Track Signal Booster (Dale's Legacy Continues)

Here's another success story for Dale and John's buffer.  I run TMCC only on a very large layout with about 2400 feet of track.  I've added earth ground wires wherever needed so the layout typically runs very well.  In order to test the unit, I disconnected an earth ground above a track in a tunnel (where there are 2 overhead tracks).  A diesel with marginal antenna would run through the tunnel with headlight blinking wildly and would sometimes stop in the tunnel.

With the buffer up and running, both blue LED and green LED lit, that same diesel runs through the tunnel smoothly at any speed with an absolutely rock solid headlight.  No flicker at all.

My DC voltage measurements are 2.75 volts at the Base terminal and 3.86 volts at the Boost terminal.

Good stuff!

I'm guessing the boost is being measured connected to the layout.  Sounds like you do have a lot of track, it's actually loading down the buffer some.

Green and red?  Are you sure you're not talking about the blue power LED?

What are you using to drive it, the original TMCC command base, or a Legacy command base?  The older TMCC command base doesn't put enough signal out to get the green signal indication.  If you're using the Legacy command base, it's not putting out a full amplitude signal.

John, I am using a Cab 1l system, I attached a pictures howing both red and green illuminated.

Ray

There's probably some oddity of your base signal, that light is directly monitoring your base signal.  It doesn't affect the buffer operation, if it's working fine, I wouldn't spend too much time on it.

Looks green (mostly) in the photo...

Ok, Thanks John, as I mentioned I did run for a short time and all seemed well. Will run more and see if signal is continually good.

Ray

Photos of LED's are difficult.   Since it's a R/G LED, at different angles, it looks different.

John, you are so right as to the difficulty in photographing the LEDs, I spent a lot of time to get the pic,almost gave up.

Ray

Yes the sensors are not like eyeballs,  but handy for seeing IR.

Ray, that is a good picture, it is exactly what mine first looked like. My advice is if the layout is working, ignore it. I still have some unexplained signal issues on my 2 rail layout but fortunately found a temporary fix that by all logic should not have any effect. My current thought is one of the AS-AR-AC boards is "defective." I am not sure if you have any of these on your layout. My illogical temporary fix is to keep track power on the Turntable pit rails which are fed through one of the AS-AR-AC boards. If I do this one thing the layout works perfectly, otherwise I have signal issues even with a solid green light on the Buffer.

Ray, if you will be at S Fest we could meet up.

Tom, As far as I know, I don't have any of those boards on the layout. I ran the locomotives that had problems for a longer period today, the problem surfaced when running as a consist. The two areas that were troublesum showed no problems now. S Fest, at this time I am not sure if I can make it but will keep this in mind.

Ray

I received my legacy control base back from Lionel today. It now has a bright green light 2.001 volts to buffer and 6.37 volts to track. everything works great. The only problem is my engine roster is gone  and the base is unnamed. I can view the list on my cell phone WiFi when not linked to base is there any way to restore roster to base?

Jprails posted:

I received my legacy control base back from Lionel today. It now has a bright green light 2.001 volts to buffer and 6.37 volts to track. everything works great. The only problem is my engine roster is gone  and the base is unnamed. I can view the list on my cell phone WiFi when not linked to base is there any way to restore roster to base?

Yes, but only if you had backed it up first.  I do this via the Windows Legacy System Utility.  If you're not familiar with this, I think you may have to enter things again from scratch.

But...if you go ahead and install and use Lionel Legacy System Utility, it's easier to install the names, numbers and options for all your engines with a real keyboard.

Not only that Chuck, but you can just use the list on the WiFi to get all of the stuff in, easier to transcribe if you have the data to look at.  Of course, if you have sensor equipped locomotives, you just drive them over the sensor track.

DM TMCC Buffer kits are now available.  I've attached the kit instructions and the buffer user's manual to this post so you can evaluate your need and your ability to construct the kit.  Each kit contains all the materials you'll need to build one buffer.  Thru-hole construction was used to make the assembly easier.  Also, the cases were prepped with the holes and slots as without the drilling fixture, that would have been more time consuming.

DM TMCC Buffer Kit Documentation.pdf

DM TMCC Buffer Documentation.pdf

Contact me via my profile address if you want one of these kits.

Been having problems with the two sensor tracks on my layout. Tried resetting them checking all the plugs. Everything seems OK. The only thing I changed was adding the booster. Disconnect the booster sensor tracks work. Checked the hookup wiring on the booster and they are in the right spots. Hook the booster back up and the sensor tracks stopped working.  The booster is about 16 inches from the Legacy base. Have a powermaster bridge nearby but I tried taking that out and it didn't make any difference.

Well, I'd try moving it farther away, but 16" should be sufficient.

As an experiment, we could try cutting down the boost, here's a simple voltage divider to reduce the amplitude of the signal while still keeping the low impedance drive.  See if this changes the situation.

I cut the trace between R5 and C6, easy to do, and soldered a couple #24 wires to the edge of the chips. And then the other ends to a 1K potentiometer. I was looking in the junk for a 2K but the 1K, 1/8 inch mounting,  is adequate for a variable gain and takes up minimal space. Instead of 3.3 gain, it now varies from 3.3 down to 1.65 which is where I leave it. Modest layout, but I like having the booster and seeing the green LED since I am familiar with the broken Legacy base with the greatly reduced output.

Be cautious tack soldering the pre-tinned wires on to the edges of the chips, because too much heat will cause the chips to slide off their pads.

I moved the booster about 10' away and no change. Don't have any resistors but I have some diodes.  The number on them is RL207. Under that it says mic. Would those be OK to try. Don't really know much about his stuff.

Diodes won't get it done.

OK so I need some resistors . Which ones and from where. Thinking maybe picking up a 1 K potentiometer also.

Well, depending on how much you want to reduce the amplitude, you need a varied selection.  You can get them from Digikey, just look for 1/4 watt thru-hole resistors, 5% ones are plenty accurate.  It's handy to have some of these around if you're doing anything with electronics.  My starting suggestion is a 1000 ohm and a 2000 ohm resistor.

OK thank you.

cjack posted:

I cut the trace between R5 and C6, easy to do, and soldered a couple #24 wires to the edge of the chips. And then the other ends to a 1K potentiometer. I was looking in the junk for a 2K but the 1K, 1/8 inch mounting,  is adequate for a variable gain and takes up minimal space. Instead of 3.3 gain, it now varies from 3.3 down to 1.65 which is where I leave it. Modest layout, but I like having the booster and seeing the green LED since I am familiar with the broken Legacy base with the greatly reduced output.

Be cautious tack soldering the pre-tinned wires on to the edges of the chips, because too much heat will cause the chips to slide off their pads.

I like the idea of having the gain adjustment. Just a little paranoid about cutting the trace and soldering onto the chips. My hands not so steady when doing stuff like that. Think gonna try the resistors first.

Gweedo posted:

Been having problems with the two sensor tracks on my layout. Tried resetting them checking all the plugs. Everything seems OK. The only thing I changed was adding the booster. Disconnect the booster sensor tracks work. Checked the hookup wiring on the booster and they are in the right spots. Hook the booster back up and the sensor tracks stopped working.  The booster is about 16 inches from the Legacy base. Have a powermaster bridge nearby but I tried taking that out and it didn't make any difference.

The sensor track is sensitive to the TMCC signal if the signal has harmonics or high amplitude.  The TMCC signal can be too high, so keep that in mind.  If your sensor tracks stop working, your TMCC signal is definately too high!!

I guess I should look into a gain modification mod for the buffer.  I'm thinking something with a pot on the top of the case connected into the circuit to allow a x1 to x3 gain adjustment.  I'll look at Digikey and pick a small pot I can attach to the top of the case...

That's what I did John. The 1K, 1/4 inch mounting pot that I had on the top of the case. I think I posted 1/8 inch before here but that was the shaft diameter

The funny thing is I did not have a 1/8 inch shaft knob, so I went on ebay and found a brand new old stock one for $1.50 BUT the shipping was $3. I should have ordered more than one knob now that I think of it.

I see Digikey has pots for 79 cents, I think I'll get a few and try out a mod.  My idea is to just replace R5 with a 2K pot and a 1K series resistor.  That allows me to vary the gain from about 1:1 to 3:1.  This also preserves the input signal monitoring indicators.  What would be really cool is a graduated dial with the gain figures on it, but I think that's gilding the lily.

I guess this explains why my 3 sensor tracks all stopped working. I only have two engines that work with them since I am in S gauge so it is not a big deal.

I'm working on a mod to vary the output gain, that retains the low impedance drive and lets you vary the amplitude of the signal to address issues like this.  Of course, you'll have to either apply it yourself or send the buffer back to me for the fix.

These are kind of nice and colorful knobs included.

f:0" target="_blank">https://www.ebay.com/itm/6x-2K...802!US!-1:rk:23f:0

They're a few bucks cheaper than I was going to spend for five from Digikey, so I ordered a set.

SantaFeFan posted:

Gweedo posted:

Been having problems with the two sensor tracks on my layout. Tried resetting them checking all the plugs. Everything seems OK. The only thing I changed was adding the booster. Disconnect the booster sensor tracks work. Checked the hookup wiring on the booster and they are in the right spots. Hook the booster back up and the sensor tracks stopped working.  The booster is about 16 inches from the Legacy base. Have a powermaster bridge nearby but I tried taking that out and it didn't make any difference.

The sensor track is sensitive to the TMCC signal if the signal has harmonics or high amplitude.  The TMCC signal can be too high, so keep that in mind.  If your sensor tracks stop working, your TMCC signal is definately too high!!

OK thank you for info.

When my pots come in, I'm going to test a gain control mod to the buffer.  Shame we didn't think of it before they were all built!   It will be a knob on the top that will vary the gain from 1x to 3x.  Once I assure myself that nothing bad happens when I fit it, I'll offer it as a retrofit mod, you can either do it yourself or send it back and I'll add the mod.

If I could only find someone to silkscreen a nice dial with the gain calibration marked...

Sounds good. Much better than me fumbling around trying to find a cure. Just disconnected the buffer for now.

gunrunnerjohn posted:

DM TMCC Buffer kits are now available.  I've attached the kit instructions and the buffer user's manual to this post so you can evaluate your need and your ability to construct the kit.  Each kit contains all the materials you'll need to build one buffer.  Thru-hole construction was used to make the assembly easier.  Also, the cases were prepped with the holes and slots as without the drilling fixture, that would have been more time consuming.

DM TMCC Buffer Kit Documentation.pdf

DM TMCC Buffer Documentation.pdf

Contact me via my profile address if you want one of these kits.

Nice kit. Good pictures and choice of components. Easy to build. 1 hour or so.
Thanks,

gunrunnerjohn posted:

DM TMCC Buffer kits are now available.  I've attached the kit instructions and the buffer user's manual to this post so you can evaluate your need and your ability to construct the kit.  Each kit contains all the materials you'll need to build one buffer.  Thru-hole construction was used to make the assembly easier.  Also, the cases were prepped with the holes and slots as without the drilling fixture, that would have been more time consuming.

DM TMCC Buffer Kit Documentation.pdf

DM TMCC Buffer Documentation.pdf

Contact me via my profile address if you want one of these kits.

John,

Just checking, but these are now listed as "TMCC buffer" kits - I assume these are the same as the original "TMCC/Legacy booster"  items - just in kit form ?

Probably missed the post, but are these compatible with Legacy being run through a DCS TIU/WiFi/SER 2 system ? 

Cost ?

Thanks

These are identical in function to the first run of assembled units, I didn't think I'd be able to assemble enough orders to do another SMT production run, so I just changed over to thru-hole components to make the kit version.  The circuit and function is identical to the assembled version (at least after you assemble it).

These have nothing to do with the serial data from the Legacy, and they don't affect it either.

Just finished testing the signal amplitude mode, so far, so good.  It varies the output amplitude from around 1.1:1 to 3:1 from stop to stop.   Most folks won't need this, however if you're running LCS Sensor Tracks, or you have experienced DCS issues after adding the TMCC Buffer, this mod may be the ticket to the two systems coexisting.

The installation is fairly simple, see pictures and description below.

 Remove R5 and solder pot and resistor combination across the R5 connection

Close-up detail of pot and resistor assembly

Drill hole(s) for amplitude adjustment pot

Mount pot and reassemble case

That's the installation process, so it's fairly simple to upgrade the box.