Multiple LEDs on FX-DO


Joó Ferenc
 

I have a couple of the Titan FX-DO decoders designed for O scale but am using them in two G scale SD45 locos as the 8 Amp peak (4 Amp continuous) is plenty enough to drive them. 

However, that's just it, as I am having trouble configuring the lights, so I am driving without the lights.

The FX-DO has two 8-pin connectors, each of which have 6 function ports, a ground and a 5 Volt + pin.

The Titan is great as has separate step lights and truck light outputs. However, usually you need to add 4 LEDs for both, or in the case of step lights, you have a few along the catwalk around the loco. In my case, I added two more step lights to where there are steps at the cab doors, so I would need 9 LEDs to be driven from the same port.

Sadly, 5 Volts are not even enough to drive two LEDs for say tail lights and Kelly suggested to use an opto isolator and a separate device for power, to drive any consumer that need a higher voltage or power.

I guess it is not wise to connect the LEDs to the track + port as then the function ports will receive track voltage which in my case is 24 Volts, and that will likely damage the decoder.

Now I know that there are some decoder manufacturers who have 5V+, 10V+ and track voltage + on their decoder (like Zimo and I think ESU, too) but I presume this is not the case with the Titan FX-DO. Would anyone have any knowledge on this, please?

Any suggestions on how to connect say 9 step lights to the FX-DO? Obviously I furst need to split them in two circuits as 24 Volts wouldn't be enough for 9 LEDs if they all need like 3 Volts each.

Thanks.

Üdvözlettel,
Best regards,
MfG,

Ferenc Joó
Correspondent for Hungary
TREU - Today's Railways Europe
IRJ - International Railway Journal
GSM:   +36204141621

NOHAB Apartment
8263 Badacsonytördemic
Debreczenyi u. 9. / HUNGARY
"The holiday apartment on Lake Balaton
with its own garden railway!"


kjlovesya
 

Hello Joo,

  Sorry about your name spelling.  I don't know how to type accents on my keyboard.

  I have a new in box Titan FX-DO and just had a quick look.   There is a error on the drawing for the bottom board.  Perhaps Kelly could have a look at this.   Connector P2 is mislabeled "TRUCKS";  when, in fact, only pins 1 and 2 are for the trucks (as are the schematically parallel P1 pins 1 and 2).   Connector P2, pins 3 and 4 are to be connected to the motor (as are the schematically parallel P1, pins 3 and 4).

  That being said, the wires from P1 are labeled correctly.

  If you look at the bottom of the bottom board, you will notice a large black box component with a hole in the middle.   That is a heavy duty, full wave bridge rectifier.   If you understand how a bridge rectifier works you will know that the voltage across the + and - side (output) is track voltage minus 1.4 volts.   In your case you will have 24 V - 1.4 V = 22.6 V total.

  Kelly recommends using an opto-isolator between the lighting and the top board.   This is the safest route as the expensive decoder board is protected.  The input side of an opto- isolator is internally similar to an LED.  You connect one side to plus +5 V and the other is connected to the decoder light port via a current limiting resistor.  The output side of the opto-isolator can then be used as a simple switch.  N.B. the isolated circuit, controlled by the output of the opto-isolator, must have the GND connected to the GND of the controlling circuit (the "-" side of the full wave bridge rectifier - same as the top board P1 - 8 and P2 - 8).

  A note about LEDs in series.   While red LEDs run around 2 volts,  white LED takes about 3 volts to turn on (some actually take 3.1 or 3.2 V to turn on).  Current controls the brightness.   That's why it's absolutely mandatory that a current limiting resistor be included in any LED circuit.   A +5 volt circuit can only drive one (3 Volt) LED.  However, a +22.6 Volt circuit can drive up to seven LEDs; 3 V X 7 = total 21 Volts (which is less than 22.6 Volts leaving room for the current limiting resistor). 

  We must choose our maximum current for the LEDs.    Most electronics engineers recommend a current maximum of 20 mA.  I use varied current depending on the LED function.   Headlights are brighter than ground lights.  For Headlights I might use 15 mA (very bright) while a ground light might only require 2 mA (considerably dimmer).

  Let's do some math.  Please excuse the simplicity, but this is a forum and our audience may not know how to calculate resistance:

e.g.    22.6 V  -  ( X  3 V)  =  1.6 V        We now use Ohm's law to figure out the resistor value for a 2mA circuit.       Volts = Amps X Ohms    or  Ohms = Volts / Amps

    1.6 V = 0.002 Amp X Ohms   or    Ohms = 1.6 V / 0.002      We get 800 Ohms.   If we don't have the exact value resistor we choose a value slightly larger.  We can use 1000 Ohms (1K Ohm, 1/8 Watt) with no problems.   


  If you decide to add more LEDs, you may add a second series circuit in parallel with the above series circuit.   Use the same formulas adjusting for quantity of LEDs in the series circuits.


  I hope this helps.   Let us know if you have any questions (or corrections).


Best regards,
KJ


Joó Ferenc
 

Hello KJ,

Thanks. Is your FX-DO for sale?

Now down to the point. I understand all what you said and will look for a solution to operate more than one LEDs on one port, under the condition that I can actually get the decoder ports working!

My problem is that the ports are all messed up by default, as it seems, and I can't get them to work the way I want.

There is, of course, no manual for the FX-DO and it's impossible to figure out what function is assigned to what port.

Now this probably wouldn't normally be a problem but my Quantum Programmer also developed a fault recently and I can't get it to work. Thus I tried manual programming of CVs.

I reset the decoder, I set all the values of all the CVs shown in the Feature to Port Mapping table of Quantum CV Manager to zero, so in theory no lights should be operating. And still I have some lights that are on. Then I try to assign features to a certain port but they are not in the sequence as the pins on the decoder. This is what I could identify so far:

pin2 = port 4
pin3 = port 3
pin5 = port 1
pin6 = port 8
-------------------
pin9 = port 5,

where the first two pins on each 6-pin connector are GND and 5V+, thus I call pins 3-8 of the first connector as pins 1-6 and pins 3-8 of the second connector as pins 7-12.

So I am trying to figure out for example what port is assigned to pin 4. I have no feature assigned to anywhere and try to set, say, step lights to pin 4. I try all the values from 1 to 12 on CV 115.113.0 and the single light attached to that pin will not be on for any of those values.

This just drives me crazy, I thought I could at least manually figure out what pin corresponds to what port but no such luck...

KJ, do you think you could perhaps see what function output pin on your FX-DO corresponds to what port?

Thank you.

Üdvözlettel,
Best regards,
MfG,

Ferenc Joó
Correspondent for Hungary
TREU - Today's Railways Europe
IRJ - International Railway Journal
GSM:   +36204141621

NOHAB Apartment
8263 Badacsonytördemic
Debreczenyi u. 9. / HUNGARY
"The holiday apartment on Lake Balaton
with its own garden railway!"


kjlovesya via groups.io <kjlovesya=yahoo.ca@groups.io> ezt írta (időpont: 2021. febr. 14., V, 19:48):

Hello Joo,

  Sorry about your name spelling.  I don't know how to type accents on my keyboard.

  I have a new in box Titan FX-DO and just had a quick look.   There is a error on the drawing for the bottom board.  Perhaps Kelly could have a look at this.   Connector P2 is mislabeled "TRUCKS";  when, in fact, only pins 1 and 2 are for the trucks (as are the schematically parallel P1 pins 1 and 2).   Connector P2, pins 3 and 4 are to be connected to the motor (as are the schematically parallel P1, pins 3 and 4).

  That being said, the wires from P1 are labeled correctly.

  If you look at the bottom of the bottom board, you will notice a large black box component with a hole in the middle.   That is a heavy duty, full wave bridge rectifier.   If you understand how a bridge rectifier works you will know that the voltage across the + and - side (output) is track voltage minus 1.4 volts.   In your case you will have 24 V - 1.4 V = 22.6 V total.

  Kelly recommends using an opto-isolator between the lighting and the top board.   This is the safest route as the expensive decoder board is protected.  The input side of an opto- isolator is internally similar to an LED.  You connect one side to plus +5 V and the other is connected to the decoder light port via a current limiting resistor.  The output side of the opto-isolator can then be used as a simple switch.  N.B. the isolated circuit, controlled by the output of the opto-isolator, must have the GND connected to the GND of the controlling circuit (the "-" side of the full wave bridge rectifier - same as the top board P1 - 8 and P2 - 8).

  A note about LEDs in series.   While red LEDs run around 2 volts,  white LED takes about 3 volts to turn on (some actually take 3.1 or 3.2 V to turn on).  Current controls the brightness.   That's why it's absolutely mandatory that a current limiting resistor be included in any LED circuit.   A +5 volt circuit can only drive one (3 Volt) LED.  However, a +22.6 Volt circuit can drive up to seven LEDs; 3 V X 7 = total 21 Volts (which is less than 22.6 Volts leaving room for the current limiting resistor). 

  We must choose our maximum current for the LEDs.    Most electronics engineers recommend a current maximum of 20 mA.  I use varied current depending on the LED function.   Headlights are brighter than ground lights.  For Headlights I might use 15 mA (very bright) while a ground light might only require 2 mA (considerably dimmer).

  Let's do some math.  Please excuse the simplicity, but this is a forum and our audience may not know how to calculate resistance:

e.g.    22.6 V  -  ( X  3 V)  =  1.6 V        We now use Ohm's law to figure out the resistor value for a 2mA circuit.       Volts = Amps X Ohms    or  Ohms = Volts / Amps

    1.6 V = 0.002 Amp X Ohms   or    Ohms = 1.6 V / 0.002      We get 800 Ohms.   If we don't have the exact value resistor we choose a value slightly larger.  We can use 1000 Ohms (1K Ohm, 1/8 Watt) with no problems.   


  If you decide to add more LEDs, you may add a second series circuit in parallel with the above series circuit.   Use the same formulas adjusting for quantity of LEDs in the series circuits.


  I hope this helps.   Let us know if you have any questions (or corrections).


Best regards,
KJ


kjlovesya
 

Hi Joo,

  Sorry, the decoder is not for sale.  I have a locomotive in which I want to install the decoder.  

  I'm not sure that we have the same decoder.  I just checked, mine is the Titan FX-O.  # 670-0200.    My top board has two banks of 8 pin connectors, labeled P1 and P2,  totaling 16 wires =  12 functions, 2 X +5 V and 2 X GND wires.  

  Did you do a query on what version you have?  You can use CV 64 to query CV 7 .    POM --> CV 64 = 7    The decoder should speak the version number.

  Also, you can check build information.   See the big 483 page manual on page 393.

  Pages 410 and 411 show light port to feature mapping CVs.

  Try a reset, cycle the power, then do a query of each light feature.   Then assign the correct light to each port.   If you have a computer attached to an NCE system you can use the CV Manager to do the same.

  I'll have a look tomorrow and see if I can wire the decoder to some kind of test fixture.  It's not yet installed in a locomotive.  It may take a while.

Best regards,
KJ


peteski7
 

Hello Joó,
While I can't help with the decoder specific question, I have commend on the LEDs.

Instead of hooking up the LEDs in series, requiring rather high voltage., why not hook them up in parallel (with each LED having its own current limiting resistor)?  Yes, the wiring is slightly more complex, but not impossible.  Resistor (a small SMD 0603 or 0805 size) could be installed directly at the LED's lead, so you woudl just need 2 wires for the string of LEDs.
While the typical operating current for larger size white LEDs is often specified 20mA, most smaller SMD LEDs (0402, 0603, 0805 size) have operating current of 5mA.  Either way, even 5mA is often too bright for applications other than headlights. Often 2mA (or even less current) produces realistic brightness.  With that in mind, you could easily run a string of parallel-connected LEDs using standard function output, and the decoder's common positive power (either 5 or 12V).

As far as creating an external source of positive voltage (the blue wire), you can build a very simple circuit that will do that.


Instead of using 2 discrete diodes, there are pairs of common-cathode diodes in a 3-pin packages available to simplify the construction.
Peteski


Joó Ferenc
 

Thanks KJ and Peteski,

I will try to have the decoder read out loud the CVs although even at reset it didn't say reset.

For the diodes from the track pick-up, that should not be needed if I connect to the bridge rectifier, if I am correct.

Thanks for your input. Maybe I should get a new Programmer... Anybody has one for sale?

Üdvözlettel,
Best regards,
MfG,

Ferenc Joó
Correspondent for Hungary
TREU - Today's Railways Europe
IRJ - International Railway Journal
GSM:   +36204141621

NOHAB Apartment
8263 Badacsonytördemic
Debreczenyi u. 9. / HUNGARY
"The holiday apartment on Lake Balaton
with its own garden railway!"


peteski7 via groups.io <peteski7=yahoo.com@groups.io> ezt írta (időpont: 2021. febr. 15., H, 4:23):

Hello Joó,
While I can't help with the decoder specific question, I have commend on the LEDs.

Instead of hooking up the LEDs in series, requiring rather high voltage., why not hook them up in parallel (with each LED having its own current limiting resistor)?  Yes, the wiring is slightly more complex, but not impossible.  Resistor (a small SMD 0603 or 0805 size) could be installed directly at the LED's lead, so you woudl just need 2 wires for the string of LEDs.
While the typical operating current for larger size white LEDs is often specified 20mA, most smaller SMD LEDs (0402, 0603, 0805 size) have operating current of 5mA.  Either way, even 5mA is often too bright for applications other than headlights. Often 2mA (or even less current) produces realistic brightness.  With that in mind, you could easily run a string of parallel-connected LEDs using standard function output, and the decoder's common positive power (either 5 or 12V).

As far as creating an external source of positive voltage (the blue wire), you can build a very simple circuit that will do that.


Instead of using 2 discrete diodes, there are pairs of common-cathode diodes in a 3-pin packages available to simplify the construction.
Peteski


kjlovesya
 

Hi Joo,

  Thus far you have suggested you'd like to purchase 1/ a QSI Titan FX-DO and 2/ a QSI programmer.  

  All of these items are new in stock at QSI.  Why don't you simply ask QSI?   Kelly is from QSI and provides great customer service.  Here's Kelly's email address: qsindustries224@....

KJ


Joó Ferenc
 

Hi KJ,

I e-mailed Kelly several times but no response for several months.

He did say he has these in stock a year ago but he doesn't respond lately. I heard his life is not simple these days.

Üdvözlettel / Best regards / MfG,

Joó Ferenc / Ferenc Joó
NOHAB Apartman
Badacsonytördemic, Hungary
http://nohabapartman.hu
GSM: +36 20 4141 621

Sent from Samsung Galaxy A3 (2017) phone

kjlovesya via groups.io <kjlovesya=yahoo.ca@groups.io> ezt írta (időpont: 2021. febr. 15., Hét 18:46):

Hi Joo,

  Thus far you have suggested you'd like to purchase 1/ a QSI Titan FX-DO and 2/ a QSI programmer.  

  All of these items are new in stock at QSI.  Why don't you simply ask QSI?   Kelly is from QSI and provides great customer service.  Here's Kelly's email address: qsindustries224@....

KJ


kelly dorf
 

Sorry gentlemen.  I do have them in stock. I am trying to get caught up.

On Mon, Feb 15, 2021 at 9:50 AM Joó Ferenc <ferencj@...> wrote:
Hi KJ,

I e-mailed Kelly several times but no response for several months.

He did say he has these in stock a year ago but he doesn't respond lately. I heard his life is not simple these days.

Üdvözlettel / Best regards / MfG,

Joó Ferenc / Ferenc Joó
NOHAB Apartman
Badacsonytördemic, Hungary
http://nohabapartman.hu
GSM: +36 20 4141 621

Sent from Samsung Galaxy A3 (2017) phone

kjlovesya via groups.io <kjlovesya=yahoo.ca@groups.io> ezt írta (időpont: 2021. febr. 15., Hét 18:46):
Hi Joo,

  Thus far you have suggested you'd like to purchase 1/ a QSI Titan FX-DO and 2/ a QSI programmer.  

  All of these items are new in stock at QSI.  Why don't you simply ask QSI?   Kelly is from QSI and provides great customer service.  Here's Kelly's email address: qsindustries224@....

KJ


kjlovesya
 

I just did a little more inquiry.    The top page of my decoder paperwork is labeled  FX-O-TOP .    That's what I reported above.   However, when I ran the QSI software it reported:  FX-DO 7021 hardware.   Kelly if you want to contact me off list I can spell out the errors I've found.

Joo, according to the paperwork, there are 12 light ports on this decoder L1 - L12.   L1 - L6 correspond with pins 1-6 on the top board - P1 connector and L7 - L12 correspond with pins 1 - 6 of the P2 connector.     I would suggest you do another full decoder (all CVs) reset.


Best regards,
KJ


kelly dorf
 

If you have a Quantum Programmer and the CV manager software, you can totally re-map and re-configure your light ports to your liking.

Kelly


peteski7
 

Joó,
That dual-diode circuit I attached is simply the positive half of a bridge rectifier. Since you only need positive voltage for as the common for function to work (negative is provided through the decoder), the negative half of the bridge rectifier is not needed. 

I model in N scale, so I need to find smallest possible solutions.  A dual diode is smaller than a bridge rectifier.  Actually this dual-diode common-positive circuit is used by many manufacturers for headlight power on factory installed light boards that include a 6-pin decoder plug (since 6-pins do not include the "blue" common positive output).
Peteski

On Mon, Feb 15, 2021 at 02:25 AM, Joó Ferenc wrote:
Thanks KJ and Peteski,
For the diodes from the track pick-up, that should not be needed if I connect to the bridge rectifier, if I am correct.
Üdvözlettel,
Best regards,
MfG,