I have been installing decoders in a bunch of old P2K cab units I have. FAs, Erie Builts, C Liners. So I have a Digitrax DH123 decoder, pretty basic but cheap and I'm using FOF for the headlight but I'd like to have an LED that's always on regardless of direction. So if the blue wire is 12v+ I wonder where I can find a non-function minus.
I've tried using FOR but I can't assign that function to be always on. The DH123 is pretty limited for lighting functions.
My other option would be a rectifier across the track pickup and feed constant DC to the LED I just wondered if there was an easier way to have always on numberboards?
Thanks... ED
You can connect both the white and yellow wire to the cathode of same led. That will allow the light to be on in either direction as long as F0 is on. You might also be able to do it with programming but connecting both wires has always been simpler for me when doing A units.
You can actually have as many of the function wires as you want wired together. That's how to have a single light capable of doing different things depending on individual function programming. Remember that the colored function wires all lead to negative so they can all be connected together without damaging teh decoder. Just don't connect the positive blue wire directly to them.
Martin Myers
Thanks Martin,
That would be an option but I'd also like to maintain headlight control so if the unit is trailing or parked I can extinguish the headlight but keep the numberboards lit.
Digitrax insists that this decoder has a Mars light, ditch lights, flickering, strobe and all... well I sure can't find them. And when I try to program FOR to "non-directional always on when function on" using decoder pro it makes no change in the headlight operation at all!
http://www.digitrax.com/products/mobile-decoders/dh123d/
As a last resort I would wire white and yellow together as you suggest.
Thanks for your help...
You can also just add track power to LED's and power them from that. Use a 1k resistor and hook one lead of the LED to one rail ( right rail) of power and the other lead of the LED to the other rail ( lest rail) power. The LED will be on whenever there is power to the track. Just don't forget to use the resistor on one of the leads.
Hi Woodone,
I think I may have done that sometime years ago in a decoder install but I forgot which engine. I'm always under the impression that there's AC on the rails so I'd need a diode bridge to power an LED. I will give that a shot in a few minutes and get back to you... If that's the case it's exactly what I'm looking for!
Thanks much! Ed
woodoneYou can also just add track power to LED's and power them from that.
Well, I'll eat my hat! That's the answer I was looking for. It's been a while since I've done any "basic" decoder installs and I know I've done something like this in the past but just couldn't quite jog the old memory banks.
I just took an LED and a 1k and, sure enough, it lights no matter which rail you contact
I have always been a big fan of Digitrax but their documentation is very frustrating to say the least!
Thanks for your help!
Ed
gmpullmanDigitrax insists that this decoder has a Mars light, ditch lights, flickering, strobe and all... well I sure can't find them.
Looking at the link you provided, if you scroll down to the bottom where the specifications are there is something called "FX3 read more" in red. If you click on that it expands the page to include some information on a bunch of lighting functions that appear to be what you want.
gmpullman Hi Woodone, I think I may have done that sometime years ago in a decoder install but I forgot which engine. I'm always under the impression that there's AC on the rails so I'd need a diode bridge to power an LED. I will give that a shot in a few minutes and get back to you... If that's the case it's exactly what I'm looking for! Thanks much! Ed
The LED connected to the rails with a resistor is the way to go. NCE does that with the Power Cab DCC controller. I checked mine and that is how the LED on the power panel is connected.
Some users assumed the LED is connected to the power pack but I traced out the circuit and saw the LED and resistor are connected directly to the DCC signal that goes to the rails.
Rich
If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.
maxmanLooking at the link you provided, if you scroll down to the bottom where the specifications are there is something called "FX3 read more" in red.
Well, that would be nice IF the DH123 supported the FX3 that Digitrax is talking about. Open the pdf on the decoder specification sheet and it says:
FX
49
F0F, forward light effect white
00
See FX
3 section
50
F0R, reverse light effect yellow
51
F1, Function 1 green
52
F2, Function 2 violet
113
F3, Function 3 brown
Not Available
114
F4, function 4 white/yellow
115
F5, Function F5 white/green
116
F6, Function F6 white/blue
See where it says F1 green; F2 Violet; see FX3 section. BUT if you look at the DH123 instruction sheet pdf it clearly states:
NOTE:The Violet and Green leads of the harness
are not used by this decoder.
The crazy Digitrax documentation is full of contradictions, enigmas, heresay and even poppycock!
You would think that after all these years Digitrax could at least proofread their own documentation and maybe clarify a few things. Perhaps Digitrax could have a local high school voc-ed class update that cryptic "Run Your Trains, Not Your Track" diagram. Clearly, this DH 123 has headlights, front and rear, and THATS ALL.
Thanks for pointing out the FX3 section but that actually applies to the DH 163. I appreciate all the help.
gmpullman See where it says F1 green; F2 Violet; see FX3 section. BUT if you look at the DH123 instruction sheet pdf it clearly states: NOTE:The Violet and Green leads of the harness are not used by this decoder.
Yes, I see that now. It's a shame that one has to go through 3 different documents looking for an answer, and still not getting one. However, I don't wish to comment on that, because someone on this same forum made a similar complaint regarding this manufacturers instructions and got blasted for it.
I am curious, however. It appears that the instructions you reference do indicate that the decoder supports two FX functions. Is it your interpretation that this means only F0F and F0R (CV 49 and 51)? The table you showed also lists F1 and F2 (CVs 51 and 52). Although the instructions state that the green and purple wires are not used, did you happen to try them anyway?
If those wires are actually not supported by the decoder, then I think you would have a legitimate beef with the manufacturer. Especially if they are selling a product that does not support what the package advertising says it does. If it were me, I'd be calling them and asking them what gives, and how they propose to correct the problem.
I don;t understnd what is crazy or misleading about that documentation, considering if you read it fromt he BEGINNING it gives the namine convention for the decoders, which would clearly indicate that a DH1<2>3 decoder only has 2 functions.
2 functions means F0F and F0R, white and yellow wires. Does for everyone else's too, except the TCS T1 which actually has 2 functions, not 1.
The 9 pin harness is a standard, it has 9 wires, even if only 7 are used. Again, everyone else's is the exact same way.
The product page for the DH123P ALSO clearly states 2-125ma functions. The instruction sheet that comes witht he decoder ALSO clearly states right at the top, 2 FX3 functions.
There may be issues with some digitrax documentation, but I fail to see one here. No where does it say the DH123 had 4 functions, the name itself syas it only has 2, as is clearly stated int he Digitrax Decoder Manual. The sheet that comes with the decoder, AND the web site entry for the item ALL state that it has only 2 functions. I don;t understand the lapse in comprehension that makes you think it has more.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
rrinkerThe sheet that comes with the decoder, AND the web site entry for the item ALL state that it has only 2 functions. I don;t understand the lapse in comprehension that makes you think it has more.
Not to be argumentative, but what are we to make of the chart that comes with the decoder "specifications" as was posted above? Do specifications suddenly have a different meaning? If the chart is incorrect, it should be corrected. And the manufacturer will not make a correction unless it is pointed out to them.
The link is the product page for the decoder - it says TWO functions, that are FX3. The next link oif for the document on FX3 functions. There are decoders with 2, 4, and 6 FX3 functions - I don;t see the misinterpretation when the decoder page clearly says it has 2 - well if it only has 2 then OBVIOUSLY the extra functions are not included.
The FX3 document litst the CVs for ALL decoders, for up to 6 functions. But the decoder in question only has 2 of them. If it was a DN143 then it would have 4 of them. If it was a DH163, it would have all 6. The chart is not incorrect, it's the exact same chart linked from every decoder's product page. FX3 is a feature specification, not a quantity specification. The quantity field in the chart is one row above the FX3 link.
(D)igitrax (H)O 1 (series) 2 (no. of functions) 3-well I forget what the last number stands for. NOT FX3. The letter after it such as 'P' or 'D' refers to the wiring. I can think of three. One comes with no wires and is ready to just plug in, another comes with a wiring harness that plugs to the decoder on one end and wires. and yet another is like a PC board type. It is ready to install-and-go but doesn't use wires or a plug.
The DH123 is VERY basic and is therefore why it is very cheap, but still a pretty good little decoder. I have...3 or 4 locos (I can't remember) that have them, although at least one I plan to upgrade (more lighting functions and sound). The decoder DOES NOT support FX3, although I think it can be programmed for Rule 17 (dimming or headlights) lighting.
The two functions are in fact FOF (Function Output Front), and FOR (Function Output Rear) for front and rear headlights, respectively.
Honestly wiring in a decoder isn't to hard. The soldering can be a little tricky, but the more you do it the better you get. The most difficult part I find is often routing the wires so they are not in the way of anything, which usually means you have to cut them a little longer or a little shorter than you want.
The wires for motor control and power pick up can be cut short, but obviously wires leading to lights mounted to the body need to be longer to allow for removal of the body.
On second thought maybe it was that last little 3 that represented series. It does get confusing. Just because a decoder has say N in it (DN143 ex.) it can be used in a different scale. I have a TCS Z scale decoder in a Bachmann HO scale 44 ton switcher. It was the smallest decoder the hobby store sold, and the 44 tonner is very little. I did ask the DCC guy there and was assured even though the TCS decoder is meant for Z scale, it has a high enough amp rating to handle the little 44.
So, story is just because a DCC decoder is for HO scale or N scale or even Z scale, you MAY be able to use it in a different scale. It all comes down to how much amperage the locomotive motor pulls, which is easy enough to measure.
Okay, can we all agree that http://www.digitrax.com/static/apps/products/mobile-decoders/dh123d/documents/DH123D.pdf is the instruction/description of the DH123D decoder?
If we agree on that, it says that:
FX 3
Function outputs for prototypical lighting effects and on/off control:
Constant Brightness Lighting with directional or independent control.
Realistic Effects like Ditch lights, Mars lights, strobes, and many more.
This is either correct or incorrect. If anyone were a potential purchaser should he not expect that the product in the package would have the features advertised?