Northern Pacific (NP) W-5 Mikado Project

[superturbine]

Really awesome Max.

Here is a thought.  In the one shot you can really see in the cab!!!  Go back and grab the interior cab details from the Mikado and install them.

[mmagliaro]

Really awesome Max.

Here is a thought.  In the one shot you can really see in the cab!!!  Go back and grab the interior cab details from the Mikado and install them.

The Kato backhead casting does not fit.  I tried that when I started out with the build.  It is too chunky.  Too deep, too thick.
The other thing to remember is that I have not put glass into the windows, or an engineer figure in the window, which I
plan to do.  I am also going to put cloth cab curtains down the side, rear, edges.  All of that, and black paint, will
mask that interior quite a bit.

Having said all that... just yesterday as I was preparing it for painting, I did think that I could make my own backhead and get it in there.
Unlike the Kato one,  I can form a thin sheet of styrene and then build up the stoker pipes and basic piping and valve details on it,
and pop it in there.  So I'm going to take a whack at it.  The OMI O Scale brass engine on brasstrains.com has some really good interior
close photos of the backhead, so I can just copy that. (Good luck finding a close-up photo of an actual NP W-5 backhead... if anyone
knows of such a thing...)

[peteski]

Peteski: Yes, I could use SMD resistors.  But I'm doing this project with my eye on two things - my own engine,
and also somewhat of a build tutorial for the GHQ W-5 kit, which Gregg Scott may still release if there is enough
interest.  I'm trying to make things as general purpose and simple as I can.  Not everybody is going to want to solder
SMD components (which includes that tiny LED in the taillight).  They may end up using a larger LED inside the
tender and a piece of fiber optic tubing.  Heck, I even considered that myself.  So yes, SMD stuff is small and neat.
But I've got a lot of room up inside that tender, so I used it to keep this simple.

As for the LED shorting against the housing, I did include a shim of .005" styrene against one side
of the LED so that the magnet wire and the LED pad cannot touch the housing on that side.   I didn't show it in a photo,
but I thought I mentioned it in the captions somewhere.

TANKS for reminding me about the reverse protection diode.  I need to get that in there!
Funny I forgot that.  In the #626, I reverse-wired a Schottky diode across the SMD LED.  Those are nice because they
have such a fast switching time.  But I somehow just forgot about it here.

You're welcome - the last thing I like to do is to replace a burned out LED on some super-detailed model where the LED is permanently installed. 

As far as the SMD resistors go, IMO they are actually much easier to solder to a flat piece of PC board than dealing with a 1/8 W leaded resistor.  But that's me. 

[bbussey]

To clarify — the resistors and reverse-direction diodes are only necessary for non-decoder-equipped equipment, correct?  If a decoder was installed, then the micro LED could be soldered directly to the respective pads on the decoder board?

[peteski]

To clarify — the resistors and reverse-direction diodes are only necessary for non-decoder-equipped equipment, correct?  If a decoder was installed, then the micro LED could be soldered directly to the respective pads on the decoder board?

Well....  Correct that there is no need for reverse-voltage protection diode. The decoder circuitry itself already does that for you.

As far as the resistors go, that depends on the decoder.  Some have built-in resistors, many do not.  Also often (with white LEDs), the built-in resistor has a value which makes the LED appear too bright. Often an additional series-resistor is needed to bring the brightness down to an acceptable level.

[bbussey]

Well....  Correct that there is no need for reverse-voltage protection diode. The decoder circuitry itself already does that for you.

As far as the resistors go, that depends on the decoder.  Some have built-in resistors, many do not.  Also often (with white LEDs), the built-in resistor has a value which makes the LED appear too bright. Often an additional series-resistor is needed to bring the brightness down to an acceptable level.

Understood.

[delamaize]

I run resistors on ALL of my LED installs, DCC or DC, because all it takes is a mistake in the CV's and you'll fry that LED. it is not only piece of mind, but I feel it helps with getting the right brightness and color.

[peteski]

I run resistors on ALL of my LED installs, DCC or DC, because all it takes is a mistake in the CV's and you'll fry that LED. it is not only piece of mind, but I feel it helps with getting the right brightness and color.

How do CV values affect the operation of the LEDs with decoder-built-in or external resistors?  Whether there is a built-in resistors on a decoder or not is not affected by any CV values - it is a hardwired piece of hardware.

[delamaize]

How do CV values affect the operation of the LEDs with decoder-built-in or external resistors?  Whether there is a built-in resistors on a decoder or not is not affected by any CV values - it is a hardwired piece of hardware.

I'm 90% sure their is a CV value in the decoders I use that dictates how many volts the lighting gets. I know I have accidentally reset a decoder before, and had them fry LEDs as soon as I put them back on the track. I could be wrong and it could have been a defective decoder. Regardless, I still use resistors with LEDs, Insurance.

[peteski]

I'm 90% sure their is a CV value in the decoders I use that dictates how many volts the lighting gets. I know I have accidentally reset a decoder before, and had them fry LEDs as soon as I put them back on the track. I could be wrong and it could have been a defective decoder. Regardless, I still use resistors with LEDs, Insurance.

Do you have any specific examples or model numbers of the decoders?  I never heard of such a thing.  The closest I can think of is when some (usually H0) decoders from certain manufacturers can provide either full 12V or a 1.5V voltage on the positive blue wire of the decoders.  That is done so that the small 1.5V micro light bulbs some modelers still use can be hooked up directly to the decoder (without using a series resistor). But 1.5V would not even light up an LED.

[victor miranda]

we are straying a ways from a loco build here.

Peteski,
I believe you can find Digitraxx decoder manuals on-line.

I recall reading the 'voltage' comment in one of their manuals.
More important to me is that I doubted it was a voltage control.
my guess is variable duty square and that I was not going to trust it to keep the setting.

I decided 'voltage' was used as a easy word to skip
the more complicated and more accurate description.

victor

[peteski]

we are straying a ways from a loco build here.

Oh well.  It happens here in TRW.  You should see how far from the original build topic we strayed in Ron's Milwaukee Electric build.    How about designing TrueType fonts and making decals on Alps printers? 

Peteski,
I believe you can find Digitraxx decoder manuals on-line.

RTFM, eh? Very helpful hint Victor - thanks! 

I recall reading the 'voltage' comment in one of their manuals.
More important to me is that I doubted it was a voltage control.
my guess is variable duty square and that I was not going to trust it to keep the setting.

I decided 'voltage' was used as a easy word to skip
the more complicated and more accurate description.

victor

From how I understand that this info is for the Digitrax FX lighting (strobes, beacons, etc.) - not for powering low-voltage headlights.  Nowhere in the manual they imply that low voltage bulbs or LEDs can be utilized directly.  That is why I'm curious as to what decoder has a low-voltage function feature.

[victor miranda]

Hi Peteski,
believe me I only mentioned the on-line manuals because I thought it easier.
I have a handful of decoder manuals (a folded stapled photocopy thing?)
for various decoders....
how can I easily share them with you?

For what ever I read, the manual would have been from a number of years ago.

I would not be surprised if that specification changed for the reasons
we have been kicking around.

victor

 

[peteski]

Thanks Victor.
I have no problem reading online manuals. It is just that I have been playing with Digitrax decoders from the old DN93 (in the mid 90s) to the current versions of DZ126 and I have never encountered any CV setting mentioned in the Digitrax Mobile Decoder Manual which would allow for adjusting the function outputs for direct wired LEDs or low-voltage bulbs.

If you do have a hard-copy manual which mentions such functionality, I would like to see it.  Maybe you can scan it or take a digital photo of the page?

[reinhardtjh]

Thanks Victor.
I have no problem reading online manuals. It is just that I have been playing with Digitrax decoders from the old DN93 (in the mid 90s) to the current versions of DZ126 and I have never encountered any CV setting mentioned in the Digitrax Mobile Decoder Manual which would allow for adjusting the function outputs for direct wired LEDs or low-voltage bulbs.

If you do have a hard-copy manual which mentions such functionality, I would like to see it.  Maybe you can scan it or take a digital photo of the page?

It's in the "new" Decoder Manual V2 from Jan 2014 - page 51  So it's only available on the new Series 6 decoders.

8.7.3 CV61 Values: Transponding & Lighting Algorithm
You can set up whether transponding is enabled or disabled and which lighting algorithm you use in CV61 as shown in the following table. The factory default is 00, transponding off and LED algorithm selected.

CV 61 Value	Transponding	LED or Lamp
00	Off	LED
01	Off	Lamp
02	On	LED
03	On	Lamp