A quick measurement performed to provide quantitative data to an old discussion. Same track, same engine, same TIU, same PH180 brick.

Passive mode is with and without gunrunnerjohn's 22uH choke to block out the DCS signal from flowing into the power.

No Choke... Active voltage > Passive voltage.

With Choke... both modes pretty-much the same.

(Read the V pk-to-pk values on right, the waveform is too hard to tell)

Good to know!

signals

 

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If those are the 10 amp variety, could you post a link to the ones you use? I will add it to the list of PTCs and TVSs that no one ever looks at. Actually I will look at it and have the choke part for reference too. 

I will put this TIU Active vs Passive Mode DCS Signal Voltage information in my college text book.  I kept this book around just for days like this or for when “HeathKit” has a big comeback.

Basic Electronics

Thanks: Gary

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rtr12 posted:

If those are the 10 amp variety, could you post a link to the ones you use? I will add it to the list of PTCs and TVSs that no one ever looks at. Actually I will look at it and have the choke part for reference too. 

Digikey used to have some thru-hole ones that I've used, but they're no longer stocked.  Here's a suitable replacement, you just have to solder to the mounting pads.

Bourns Inc. SRP1770TA-220M

Okay, how this this revelation on voltage impact affect my power setup?  I'm running passive mode on my two mainlines to get more than 10 amps to the track.  I use a 34A 22uH choke.  Here is my setup:

2PH-PM-TIU-Track

The PSX-AC is set at 15.8 amps because that is all I need for the passenger train I plan to run (about 11-12 amps).  

I did a less technical test of this setup on the affect on the DCS signal only.  Without either the PSX or choke, the signal strength was 8.  With the PSX but without the choke the signal strength dropped to 5.  Adding in the choke with the PSX the signal strength increased to 9.  Used two different engines.

So, the way I read Dr. Tang's scope readouts adding the choke does two things for me: 1) increases voltage to the track, and 2) increases DCS signal.  Is that correct?

NOTE: John and the rest of you anti-more than 10 amps folks, I have no plans to go to power districts

Ron

 

TCA, TTOS, NCT, LCCA, PRRT&HS

 

Volunteers don't get paid, not because they are worthless, but because they are priceless!  Author Sherry Anderson

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CAPPilot posted:

Okay, how this this revelation on voltage impact affect my power setup?  I'm running passive mode on my two mainlines to get more than 10 amps to the track.  I use a 34A 22uH choke.  Here is my setup:

2PH-PM-TIU-Track

The PSX-AC is set at 15.8 amps because that is all I need for the passenger train I plan to run (about 11-12 amps).  

I did a less technical test of this setup on the affect on the DCS signal only.  Without either the PSX or choke, the signal strength was 8.  With the PSX but without the choke the signal strength dropped to 5.  Adding in the choke with the PSX the signal strength increased to 9.  Used two different engines.

So, the way I read Dr. Tang's scope readouts adding the choke does two things for me: 1) increases voltage to the track, and 2) increases DCS signal.  Is that correct?

NOTE: John and the rest of you anti-more than 10 amps folks, I have no plans to go to power districts

Hi there,

You're right the DCS signal should increase with the choke becasue it the PSX won't load the output of the TIU. 

The choke works by frequency selectively providing an impedance to to the TIU output port that allows AC 60 Hz to pass but not the DCS signal.

A 22 uH choke is going to provide an impedance of Zchk=j X (freq) X 2pi X L

L = 22e-6        Freq = 60    pi   = 3.14159...

 

 

At 60 Hz power this is about 0.5 ohms. Which means the power signal can go right through it without much issue as it's basically a short.

The DCS signal is at about 3.7 MHz

the impedance is Zchk=j X (freq) X 2pi X L

L = 22e-6        Freq = 3.7e6    pi   = 3.14159...

At 3.7 MHz the impedance is 30.6K...basically like an open circuit.. so it won't affect the DCS at all.

 

 

Since the 60Hz behavior is basically a short, its unlikely the choke can increase the track voltage... only the DCS signal. Also I don't know how we all arrived at 22uH... any high value.. like 10-500uH will work as long as it can handle the current. Don't go too high though or the series resistance will become a problem...

 

 

On this issue of Active voltage • Passive voltage. As an end user I am more interested in track voltage.  The MTH Premium APP shows track voltage.  What should be the high's and low's of track voltage?

This is a screenshot from my iPhone, with one engines on this line, with eight lighted passenger cars.

Track Voltage

Thanks: Gary

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trainroomgary posted:

On this issue of Active voltage • Passive voltage. As an end user I am more interested in track voltage.  The MTH Premium APP shows track voltage.  What should be the high's and low's of track voltage?

Track voltage has nothing to do with the strength of the DCS signal, which is what we've been discussing.  Track voltage is a product of the transformer voltage, how good your power wiring is, and how clean the track and your wheels and pickups are.

gunrunnerjohn posted:
trainroomgary posted:

On this issue of Active voltage • Passive voltage. As an end user I am more interested in track voltage.  The MTH Premium APP shows track voltage.  What should be the high's and low's of track voltage?

Track voltage has nothing to do with the strength of the DCS signal, which is what we've been discussing.  Track voltage is a product of the transformer voltage, how good your power wiring is, and how clean the track and your wheels and pickups are.

Thanks John: Got it......

but can you help me to understand what is a safe range for track voltage?

Gary

There really isn't a truly "unsafe" voltage.  Generally, I like to keep the track voltage somewhere close to 18 volts as I run Legacy/TMCC and DCS.  However, DCS runs pretty good down to 12-13 volts on the track as long as there's sufficient current available.  The other constraint is TMCC/Legacy doesn't want to see more than 19 volts on the track, DCS around 22 volts.

Hi John: Thanks for the information.

I have 4 main lines with one Lionel Brick for each main lines.  Just checked the Lionel Track & Power Catalog. They say it puts out 10 AMPS / 180 Watts. but does not give the high end for the voltage.

Do you know what is the starting point on these Lionel Bricks are for the voltage?

Thanks: Gary

With 125V on mine, I get 18.7 volts.  At 120 volts they should put out about 18 volts open circuit.  Since they're 180W output bricks, 18 volts at 10 amps is... 180 watts!

Adrian! posted:
gunrunnerjohn posted:

With 125V on mine, I get 18.7 volts.  At 120 volts they should put out about 18 volts open circuit.  Since they're 180W output bricks, 18 volts at 10 amps is... 180 watts!

I can hear some EE lecturer somewhere saying "if the load is resistive only"

I don't listen to such lectures, we're playing with toys here, just a close approximation is good!

I like not putting the high current through the TIU, and I really don't miss the emergency stop, which is the major feature you loose by running in passive mode.

George,

What’s the down side of running my TIU in active mode?

There are two reasons not to operate in passive TIU mode. The first, as John mentioned, is that the E-Stop function is lost. Some, myself included, believe that it's a worthwhile function.

The second is that the variable channels may only be operated in fixed mode.


DCS Book CoverThis and a whole lot more about DCS is all in MTH’s “The DCS Companion 3rd Edition!"

This book is available from many fine OGR advertisers and forum sponsors, or as an eBook or a printed book at MTH's web store!

DCS Book Cover

This and a whole lot more about DCS WiFi is all in MTH’s “The DCS WiFi Companion 2nd Edition!"

This book is available from many fine OGR advertisers and forum sponsors, or as an eBook or a printed book at MTH's web store!

Barry

 

DCS Ambassador & author of The DCS Companion series of books

Train-Ca-Teers - All For O and O For All!

 

Barry Broskowitz posted:

George,

What’s the down side of running my TIU in active mode?

There are two reasons not to operate in passive TIU mode. The first, as John mentioned, is that the E-Stop function is lost. Some, myself included, believe that it's a worthwhile function.

The second is that the variable channels may only be operated in fixed mode.


DCS Book CoverThis and a whole lot more about DCS is all in MTH’s “The DCS Companion 3rd Edition!"

This book is available from many fine OGR advertisers and forum sponsors, or as an eBook or a printed book at MTH's web store!

DCS Book Cover

This and a whole lot more about DCS WiFi is all in MTH’s “The DCS WiFi Companion 2nd Edition!"

This book is available from many fine OGR advertisers and forum sponsors, or as an eBook or a printed book at MTH's web store!

Thanks Barry. The E-stop can be useful when a collision is imminent. I do have both editions!

I have a issue that I could use help on, I have a large layout and use 135w bricks with tpc 400 legacy and DCS with Wifi I have several connections on the layout, Since we are talking signal strength I have to move the locomotive do different spots on the layout to get them to find and load into the system, My wifi keeps timing out, I am not sure why it keeps doing that is that a signal issue or what?

Barry Broskowitz posted:

The second is that the variable channels may only be operated in fixed mode.


 

 


  

I have my TIUs set up in passive mode due to their 10 amp limitation.  I run conventional engines on my layout through the PowerMasters using the Legacy system.

I believe you can use the MTH handheld E-Stop to shut down the Powermasters if you have the TIU-Legacy Command Base cable.  I'm pretty sure I had it working before I added WiFi; need to check this again.

 

Ron

 

TCA, TTOS, NCT, LCCA, PRRT&HS

 

Volunteers don't get paid, not because they are worthless, but because they are priceless!  Author Sherry Anderson

fl9turbo2 posted:

I have a issue that I could use help on, I have a large layout and use 135w bricks with tpc 400 legacy and DCS with Wifi I have several connections on the layout, Since we are talking signal strength I have to move the locomotive do different spots on the layout to get them to find and load into the system, My wifi keeps timing out, I am not sure why it keeps doing that is that a signal issue or what?

I am not using MTH’s WI-FI device but I  am guessing that it only communicates with the control device ( phone or tablet) and the TIU. If the Wi-Fi is timing out, something may be interfering with the signal. Do you regain the signal when you move closer to the Wi-Fi box?

 

George Mason posted:
fl9turbo2 posted:

I have a issue that I could use help on, I have a large layout and use 135w bricks with tpc 400 legacy and DCS with Wifi I have several connections on the layout, Since we are talking signal strength I have to move the locomotive do different spots on the layout to get them to find and load into the system, My wifi keeps timing out, I am not sure why it keeps doing that is that a signal issue or what?

I am not using MTH’s WI-FI device but I  am guessing that it only communicates with the control device ( phone or tablet) and the TIU. If the Wi-Fi is timing out, something may be interfering with the signal. Do you regain the signal when you move closer to the Wi-Fi box?

 

yes, I have to find a spot closer to the TIU and it can take several attempts before it will program. Now I can run any ware on the layout but it seems to be only when I program my  Locomotives 

Is the Wi-Fi unit out where you can see it? Or is it hidddn away? Without adding Wi-Fi to my setup, I’ve about helped you all that I can. Are you getting a Wi-Fi related error or is it indicating that it can’t communicate with the engine? Any chance that the dcs signal strength, in the rails, isn’t strong enough at different locations on your layout? You should be able to display the signal strength, real-time from an engine as it travels the layout. 

George Mason posted:

Is the Wi-Fi unit out where you can see it? Or is it hidddn away? Without adding Wi-Fi to my setup, I’ve about helped you all that I can. Are you getting a Wi-Fi related error or is it indicating that it can’t communicate with the engine? Any chance that the dcs signal strength, in the rails, isn’t strong enough at different locations on your layout? You should be able to display the signal strength, real-time from an engine as it travels the layout. 

the wifi unit is under the table I only get he unit timed out when I go to add a locomotive to my app

It apparently can operate in a stand alone manner. If that’s the case, it may be relying on a downloaded engine database. If connected to your home network it may have access to a larger number of engines that you can add. If can reach Barry Broskowitz in this forum, he can probably help you. He has written “The DCS WI-FI Companion” book which is available on Amazon. Ok, now I’m out of ideas.

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