Micro LEDs??

Engineer-Joe posted:

Stan, yes they make both PS2 and PS3 versions.

https://mthtrains.com/20-20506-1

O Scale Premier ES44AC Diesel Engine w/Proto-Sound 3.0

Is it possible that the PS3 version uses the PS3/2 board which means it drives the PS2 lights?  I'm still not clear on the "junction board" you guys are talking about for the original PS2 version and if/what kind of buffers are additional electronics are used.  In any event, since you apparently are using the PS3 board for your G-gauge EVO (and NOT the PS3/2 board), it seems you need to ask around as to if MTH uses that same PS3 board for the O-gauge EVO.  In other words I'd duplicate whatever they did except scaling up the physical dimensions on any strip mounting hardware from 1/48 : 1/32.  I don't think you'd need to deal with 0402 LED.  I agree with GRJ's comment that messing with 40 individual LEDs, even if "pre-wired" is a disaster.

As to the LED color, I believe Green is the color most commonly used for with clean-energy, re-cycling, conservation, etc..

It does sound better. I pictured just gluing the LEDs to the plastic bar. Soldering would go pretty quick as the negative terminals of the LEDs on each side of the engine would all tie together. The positives would just run to every fourth light in parallel.

 Now if they had a PCB with the LEDs mounted sideways and covered in plastic like a waterproof LED strip, I would consider it. Having them tied together correctly and in three pieces on one side to match the engine's profile might be a problem. For money reasons, I may as well scratch build the strip as well.

I would have settled for the O scale version though.

 Handling these tiny LEDs is a big pain. I lost one as I exhailed (sighed) too heavy! I broke 2 more now with too stiff a wire connected.

I will learn.

stan2004 posted:

Is it possible that the PS3 version uses the PS3/2 board which means it drives the PS2 lights?  I'm still not clear on the "junction board" you guys are talking about for the original PS2 version and if/what kind of buffers are additional electronics are used. 

I'd rate that has pretty highly unlikely.  First off, the PS32 board doesn't have the required number of outputs, the native PS/3 board has tons more light outputs available.  You have to light all the normal stuff on the EVO plus the flashing lights.  There aren't enough light outputs on the PS32 lashup to do that trick.

Engineer-Joe posted:

Now if they had a PCB with the LEDs mounted sideways and covered in plastic like a waterproof LED strip, I would consider it. Having them tied together correctly and in three pieces on one side to match the engine's profile might be a problem. For money reasons, I may as well scratch build the strip as well.

Like I said, the LED's can face any way you want to, and also be wired any way you want them to be. As far as the covering, I'd probably consider just using clear epoxy died to the correct color to encase the strip after I tested it to make sure all was well.  The good part is all the development tools are free, I use DipTrace.

Exactly how many LED's are on one side of your creation?

Well??

20 was my first thought. If the board will drive them?

The conductor/ brakeman's side of the engine has to be made in three pieces to follow the contour of the engine.

Stan, as I tried to explain. MTH used some type of custom LED panel strip with tiny LEDs. I agree that I could use larger for ease of use. I went tiny as the current draw is less. Maybe I'm overthinking this?

I also thought that if the output voltage was set for white LEDs ( or similar) at 3 volts, I would use that.

Aren't the green 2 volt??

Here's an example with 20 lights, this board is 6" long x .25" wide with 0603 LED's.  There are five pads on the back, I forgot to add one for the common, but you get the idea.

Almost perfect John.

It would have to be very thin so maybe cut down in width some. (actually it's height when stood on it's side.)

I only got four circuits that were active. I saw your post about more but maybe that was a different soundset?

After connecting, I'd still have to mount that to something so that it would be stable under the frame if grabbed. Of course, it would also be nice to cover it's front as well for protection and looks (and maybe color?).

The technical contributors on this thread are simply amazing and a real joy to watch. I may even learn something from time to time. Do you think an aerospace engineer can learn something about electronics.

;-) Vic the Junkman

I bet GE had an easier time at this!

Looks like they could just get those self stick LED weatherproof strips and stick 'em on!

I still think your best way forward is to see exactly how MTH did their PS3 O-gauge EVO.  As you point out, you may need 3 boards on one side of the engine due to the contours.   That is, unlike those LED strips, the boards are relatively stiff so can't bend.  But with some planning and study of the dimensions, it might be you only need 1 board design which is selectively populated with LEDs. 

Green LEDs operate at a slightly lower voltage than the whites...but again I'd use whatever MTH used since it obviously works.   That's an interesting point about using the smaller micro-LEDs because they use less current.  But in your specific situation, you're using manual assembly.  The point is if you have to use slightly larger LEDs that draw a bit more current, you can always add a 2 cent resistor to each of the 4 circuits to limit the current.  I see GRJ used 0603 (.06" x 0.03") resistors in his example.  Even these can be a challenge without steady hands and above average eyesight/magnifiers.  And you're soldering 40 of them! 

Even if you go with the pre-wired approach, I'd see if you can use larger LEDs.  Apparently several have already broken.  Again, it would not be that much of an issue to add 4 resistors (one per channel) to limit the current IF that's even an issue with the larger LEDs.  A 0402 LED scaled up 32x (MTH One-Gauge) is 0.04 x 32 = 1.3" on the long side.  I'm thinking the lenses  on the prototype might be bigger than 1.3"?

Thanks again Stan and John.

I maybe wrong here but I believe the lights on the real engine are inside that slight bulge on the bottom edges of the shell's panels.

They appear to be some type of LED strip? There are also strips of lights running perpendicular underneath the shell. I haven't seen any model manufacturer copy that.

I have not seen the engine in real life.

I had thought the lights were inside the large panels attached to the bottom of the walkways. Now, I'm not sure what that is?

So if I used full sized LEDs I could attach resistors to limit current draw? Hmmm. I had not looked at it correctly.

If they  (LEDs) get dimmer with higher resistor values = than use less current?

I didn't know if the resistor itself posed any current draw?

I don't usually calculate anything this small and did not consider how to handle current draw in MAs.

I figure current draw must be something like it is with power amps and speakers. Connect more speakers (in parallel) and you load the amp down. (that's my lingo)

If you load to much below the amps capability, it'll self destruct while trying.

Seeing I've turned this into a discussion post, I may as well add another.

I figure that the real engine has air line plumbing up one side of the frame and electrical up and down the other side. So running four circuits to power the LEDs on each side could add to the realism.

You can adjust the LED current to any value you like.  If you put a larger resistor in series with the LED, it draws less current.  AAMOF, for this application, given that you have the same number of lights always lit, I think we can do this all with one resistor.  Here's the "final" version, four groups of 5 LED's in each group with a single resistor current limiting, value to be determined by how much current is available and the brightness desired.

This is a board that is .15" tall by 6.0" wide, twenty LED's in four groups of five evenly dispersed.  Connections are on the rear as is the required resistor, though the resistor could really be incorporated in the wiring to the panel and left off the back.

I think an approach like this would probably do the trick.  I put all the material on one side with no traces, it's just dead board.

In order to get OSH Park to fabricate the board, I had to make it at least .25" wide.  However, with careful milling, you can take .1" off the board and get to the desired .15" width.  That's about at thin as it's going to get.  Below .15", I don't have room to run the traces.

stan2004 posted:

Even if you go with the pre-wired approach, I'd see if you can use larger LEDs.  Apparently several have already broken.  Again, it would not be that much of an issue to add 4 resistors (one per channel) to limit the current IF that's even an issue with the larger LEDs.  A 0402 LED scaled up 32x (MTH One-Gauge) is 0.04 x 32 = 1.3" on the long side.  I'm thinking the lenses  on the prototype might be bigger than 1.3"?

Stan, I agree with you, I used 0603 size LED's, I've had good luck soldering those to the PCB.  With my approach, I don't see the need for four resistors, one should do it.  Since only one channel is on at a time, the single resistor in the common will do the trick.  What's the worst that can happen, more will turn on and drop more across the single resistor.

junkman posted:

The technical contributors on this thread are simply amazing and a real joy to watch. I may even learn something from time to time. Do you think an aerospace engineer can learn something about electronics.

;-) Vic the Junkman

I'm an aerospace fuel systems engineer retread, so yes, I think you can learn.

stan2004 posted:

I still think your best way forward is to see exactly how MTH did their PS3 O-gauge EVO.  As you point out, you may need 3 boards on one side of the engine due to the contours.   That is, unlike those LED strips, the boards are relatively stiff so can't bend.

If this is fabricated on 1/32" board, it'll flex a little. Also, if you want to spend more money, you can get a flex circuit PCB that will really flex.

gunrunnerjohn posted:

You can adjust the LED current to any value you like.  If you put a larger resistor in series with the LED, it draws less current.  AAMOF, for this application, given that you have the same number of lights always lit, I think we can do this all with one resistor.  Here's the "final" version, four groups of 5 LED's in each group with a single resistor current limiting, value to be determined by how much current is available and the brightness desired.

This is a board that is .15" tall by 6.0" wide, twenty LED's in four groups of five evenly dispersed.  Connections are on the rear as is the required resistor, though the resistor could really be incorporated in the wiring to the panel and left off the back.

I think an approach like this would probably do the trick.  I put all the material on one side with no traces, it's just dead board.

In order to get OSH Park to fabricate the board, I had to make it at least .25" wide.  However, with careful milling, you can take .1" off the board and get to the desired .15" width.  That's about at thin as it's going to get.  Below .15", I don't have room to run the traces.

Oh Boy. Is this actually a done ready to order product? Wow. but maybe a problem.

Well, the engine's frame area is about 24" long total. 9" of that goes under the cab and actually runs in the reverse sequence as the long rear hood section (under the walkways). So the 20 LEDs need to be spread out over a 24" length (can be shorter to make numbers even). So maybe 8 LEDs in front section over 8" and 16 for the rear spread out for 16"? Doesn't seem like I have enough LEDs now.

 It appears that you have 20 LEDs spread out over 6"??

I will buy them off you for your effort if that's an order you can make?

You can create the boards in whatever length you want and with the number of LED's you want on each section.  I was just posting this to show what can be done.  I'd keep the LED spacing consistent for all the LED's, whatever you end up with. 

You can also add more LED's.  If you have a total of 24 inches, each LED could be on 1" centers if you go for 24, or slightly wider spacing for 20 of them.  If they're two different boards, you'd have to have two of each style for a complete locomotive.

What you really need to know is exactly how long each section needs to be and how many LED's it will have.  Obviously, you also have to plan how they'll be wired to achieve the desired effect.  I'd probably try to see an O-gauge model and pattern it after the lights they have as far as relative spacing and light count.  As I recall, the lights reverse their operation when you go in reverse...

If out-of-pocket cost is an issue, note that a 24" long board (1/4" wide) from OSH Park would run about $10 each or $20 for both sides.  To deal with contouring, you may need multiple board designs - adding more PCB design time and overhead costs (I believe you have to order 3 boards minimum).  And you still must supply the LEDs and engage in tedious one-at-a-time soldering of tiny surface-mount LEDs.

Recall that the starting point was for you to individually mount pre-wired micro-LEDs.  Let's say you are willing to go with LEDs spaced 1" apart.  As I understand it, your G-gauge shell/chassis is not molded with chase light lenses so you can position them however you want.  Likewise, as you point out, the prototype may even use green LED strips!  If you squint just the right way at this photo from your earlier video, you can convince yourself that there are discrete points of light on the strip of light which may be individual LEDs.

Point being the model manufacturers have already taken liberties.  So how about:

You can buy LED strips where the section-of-3 LEDs are spaced 1" apart.  On eBay, search for "600 LED strip" as these are typically sold in 5 Meter strips with 600 LEDs.  Most strips seem to be 300 LEDs for 5 Meters which is 2" between sections.  You can buy green, white, whatever.  1-2 cents per LED.

Anyway.  De-solder or disable 2 of the 3 LEDs in each section.  Now you have 1 LED per inch.  The key is that the ground or "-" runs along the entire strip and the remaining LEDs should be connected - this is half of the wiring mess.  The tedious part is now to daisy-chain every 4th LED (or is it every 3rd?).  There is some work to do to map the PS3 lighting outputs to the LEDs.  As you know, the LEDs chase outwards or inwards from what appears to be the center of the chassis.  To be clear, this still involves some tedious soldering of fine gauge (e.g., #30) wire...but no soldering of the surface-mount LEDs themselves. 

Boy, that's still a LOT of tedious wiring Stan.  However, as you say, you're not actually soldering the LED's onto the PCB, so it's somewhat of a toss-up.  The PCB makes a much cleaner installation when you're done however with no wiring jungle inside.

Stan, I thought I had found a better idea so I already ordered it. I like the "green" idea. So....

http://www.mpja.com/50-Micro-L...roductinfo/31988+OP/

So I've ordered 0402 warm white, 0603 that came cool white, #26 wire in eight colors that is too big, magnet wire that I saw in a utube video, green batt op LED string......

and now maybe 600 LED strips. 

I'll go look at them.

every time I try and select the 600 LED 3 color option on Ebay, something goes wrong. They list as 300/600 but they don't allow the correct choices?

I clicked on six or more links. I guess I could either pick 300 colored RGB or all green and disable the actual strip?

I know what you mean - you have to almost get lucky to find a listing with pulldown options that works.  I don't know if this is the best price but it took me less than 30 seconds to find this one that "worked" - cut and paste this listing # into the eBay search: 132065821845

I do NOT recommend a RGB LED strip for your application.  First, they are probably more expensive per-LED since each LED has full R, G, and B capability and you only need the G.  Second, RGB LEDs are physically bigger than a typical Green-only LED...and I figure size matters in your application. 

Remember that we're just thinking out loud here.  There's still the unresolved issue of whether or not the PS3 electronics can directly drive 10 LEDs per channel with sufficient current (brightness).  As GRJ observed in your other thread, when he loaded the EVO soundset and ran it on his PS3 test board, he observed how different LEDs turned "off" when the chase direction reversed.  I still think some homework is required to map the PS3 outputs to the LEDs to create the inward and outward chase sequences.

What size magnet wire did you get?  If you are handy with a soldering iron, magnet wire might be just what's needed for daisy-chaining LEDs on a LED strip.  I figure what you are doing is a one-off.  No one else has stepped forward saying they are interested in a G-gauge EVO.  Hence, it comes down to whatever YOU want to do - however much effort YOU want to put into it.  I agree with GRJ that the LED strip method is still a lot of tedious soldering...but if you aren't familiar with DipTrace or equivalent PCB program, the learning curve to make a seemingly simple strip of LEDs should not be under-estimated.

I really appreciate all the help from you both. I have to weigh my capabilities, vs price, vs time, etc.

I ordered #30 magnet wire as a guess.

I will look at these lights now.

Wow. That was easy! I ordered the all green and it came to 4.99!

My reference to 4 LED is based on the wiring of the PS-3 Diesel kit.  I believe the number boards where all driven off one output.  So 4 LEDs on a circuit.

How many they can take is unknown, but I will tell you I have run across PS-3 boards with a blown LED circuit.  HL as example.  If the buffer resistor it may be able to be repaired.  If the micro chip no such luck.  G

Thanks again G!

Well? after waiting a week my supplies are arriving. I noticed that if I put the batteries in the green micro LED lights they don't work? If I don't put the last battery all the way in, they do work!

and the shrink wrap was supposed to be 1mm. I believe this maybe more like 1"? I could put my.... thumb inside maybe?

Looks like you ordered the 1" instead of the 1mm heatshrink.  Either that or they are VERY confused.

Well I really don't know what direction I will go in the end. Here's a test of 10 green micro SMD LEDs in parallel with a 300 ohm resistor on a channel.

I had to start somewhere, so I guessed! How would I figure out just how many I could drive per channel? Add until it pops??  or would they just get dim?

I may use a 12volt strip? stay with these? or make my own???

( I swear the board took longer to fire up? I'm not sure if it didn't like the extra load, reconfigured itself for it, or I was just nervous?)

As I see it, there are two related but separate questions.

Q1. How much current can the PS3 outputs safely deliver when configured in the soundset for the chasing mode.

Q2. How to configure and mount 40 LEDs - loose LEDs, pre-wired LEDs, LED strip, LED rope, fiber-optics, fill-in-the-blank, etc.

1. As the MTH service techs have not volunteered a spec from a service bulletin or whatever MTH supplies them, I don't think this info is forthcoming.  The most useful info to date is anecdotal in that one engine was observed to parallel 4 LEDs.  As mentioned, I think the best approach is to find a PS3 EVO and see how they did it - specifically if there is additional electronics to buffer the LEDs.  But if that's not in the cards I would not try the destructive, add-load-till-it-fails test.  As GGG points out, the PS3 LED outputs are different in that a PS2 transistor that drives a lamp output is repair-able/replace-able whilst the PS3 microchip that drives a LED output is not.  If one had suitable measurement tools, the output capabilities of the four chasing outputs could be estimated.  The idea is to watch how the voltage/current at the output change as you vary the load.  But the procedure is somewhat tedious and is complicated by the pulsing of output. 

So what to do.  Well, are 10 LEDs in parallel plus a 300 ohm resistor in series bright enough?

There is some simple back-of-envelope calculation that suggests you can lower the 300 ohms to safely boost overall brightness.  Consider that a typical LED driven under nominal test conditions looks like a 150 ohm resistor.  That is you put 3V across it, and it draws 20 mA.  V=I x R.  So R = V/I = 3V / 0.02A = 150 ohms.  So we know that the PS3 output can drive a 150 ohm resistor.  By installing a 300 ohm resistor, you are guaranteeing the PS3 output will see a lighter load than even a single LED.  The takeaway of course is, in lieu of finding the exact MTH PS3 EVO hookup, adding a spot for the series resistor is the thing to do.

2. Since even the manufacturers are not accurately modeling the prototype lighting, it seems up to you as to mounting method.  Just my opinion but the idea is to simply show-off the chasing lights and changing sequence for charging vs. discharging.  To that end, whatever gets the job done.  If the spacing is not exact to the prototype, or not mounted at the right angle as to the prototype, etc.. then oh well.  I still believe that you want to employ some method that does not require tediously routing/mounting 40 pairs of loose wires - in other words some kind of strip, bar, whatever that pre-positions many LEDs and can be soldered/assembled/tested on the bench before installation to the chassis.

Stan, thank you for the help and concern. I didn't have any other way to do it. So I took a stab at it. It worked with ten so I added more! I know that's not the best, but I really feel like it was the only way. I waited for what felt like months for someone to get me info or the correct parts. I only have the PS2 version to look at. I didn't even open it up as I felt that wouldn't help me here.

 Here is a rough idea of what it will look like. I haven't verified which circuit is first, for sure.

stan2004 posted:

 

There is some simple back-of-envelope calculation that suggests you can lower the 300 ohms to safely boost overall brightness.  Consider that a typical LED driven under nominal test conditions looks like a 150 ohm resistor.  That is you put 3V across it, and it draws 20 mA.  V=I x R.  So R = V/I = 3V / 0.02A = 150 ohms.  So we know that the PS3 output can drive a 150 ohm resistor.  

Hmmm. Well we said it may handle 4 LEDs. So wouldn't that be 4 x that? V=IxR or R = 3V/ .08a = 37.5 ohms

So I don't know the model # of these LEDs. They say 1mmx 4mm online. I think they measure somewhere near 1.1mm x 3.5mm. I looked up what was close on the Digikey site. I believe they maybe 1206's? 

Ah sugar! I just found out that 2 sets of wires were in the wrong groups. 2 groups had a double wire set from the same channels. 2 other groups were correct.

Yes, probably 1206 and your online source rounded 3.5mm to 4mm.  But don't bother with the dimension of the package.  As you posted in an earlier table, the package size essentially governs how much power (Watts) can be handled and with the 300 ohm resistor there you are no where near pushing any limits of power/heat dissipation.

The 4 LED "math" is unfortunately a bit more subtle.  This goes to my comment about measuring how the PS3 output responds over a range of load conditions. While you may be able to hook up and illuminate more than 1 LED, we do not know how the incremental burdening affects the output.  That is what measuring/characterizing the PS3 output would do - but this is somewhat tedious to perform especially when the output is pulsing on and off.  If you are a glutton for punishment, this exercise is known as finding the Thevenin equivalent (google it) of the PS3 output.  In the absence of schematics or specifications, this is a method to determine what you have available.

What it would show is that there is internal resistance on each output that you can't bypass.  This means you can't just multiply or divide loads by 4 to extrapolate behavior. 

But if you have 300 ohm in series with the output, you can go ahead and load it with as many LEDs as you want and it will be a lighter load than a single LED with no resistor.  That is, you could be an infinite number of LEDs in parallel or even short-circuit the output to ground - the 300 ohm series resistor would limit the PS3 output to less than what a single LED would draw so you're safe.

Thank you for that explanation. This is really out of my league. It did work though! I'm glad it was posted to add that resistor! I put one on each of the four channel's returns. I believe they are split between 2 pins on the board, but I didn't check that for sure.

http://hyperphysics.phy-astr.g...ectric/thevenin.html

I see it, I don't understand it fully. Good thing I got help.

Ah boy. Now these showed up and I'm waffling back and forth deciding to use them or not.

Thanks Greg for your help, as usual you the go to for Modern tech info...