1:450 Scale Crossing Flasher and other projects

[Jesse6669]

I'm hoping to jump into some small scale (1:450) lighting projects, but have not touched a soldering iron for years or really done much electronic work.  I'm pretty good with small/detailed work but just haven't practiced soldering in a long time.  I figured doing a crossbuck flasher would be a good project to hone skills, so here are my questions, and any advice is greatly appreciated.
1.  I'm thinking the easiest soldering iron solution given the size of the work is a small battery powered soldering iron like the Weller or Hakko, with rechargeable batteries.
2.  I seem to recall one should use silver solder/non resin core with some flux...but I think this was for trackwork.  Is this the way to go with wiring? Any recommendations here?   Remember mainly soldering very small wires but maybe track in the future.
3.  Lighting.. is the 0402 the smallest LED?  I can find them in assorted colors online easily enough (who are recommended suppliers though?).  I'd really like a smaller LED, like .3mm diameter.. 
    3a. Is fiber optic a decent alternative (can it be bent 90 degrees?)
4.  T scale runs on 4.5-5 volts DC.. (the main motor are 3mm DC motors designed for (among other things..) cell phone vibraton.   I see the "micro litz" are 2v.. so resistor is needed I take it?  Will a flasher circuit run on just a couple AA i.e. 1.5v in parallel (see  below).
5.  What recommendation for a flasher circuit?  Off the shelf preferably, but if a kit I can solder that's ok too.
Here's the crossbuck I'd like to illuminate. 

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I'm sure there will be some experimentation needed but that's to be expected.  Thanks!
Jesse

[DKS]

OK, so here are my answers, having done just what you're doing many moons ago (a decade, to be precise). Here's what I built:



I also made an overhead gantry style flasher, but I have no photos of it owing to a computer crash (I also lost the videos I took of the flashers working). Construction was much the same, though. I made them from separate brass parts, as opposed to a photo-etching. The targets are tiny brass washers, and the hoods are made from thin-wall brass micro-tubing drilled out to be even thinner. The crossbucks were printed on self-adhesive label stock with a laser printer. Incidentally, the flasher shown here has four heads, instead of just two, as per real flashers.

1. Soldering iron: I use a thermostatted iron with a fine pencil tip. Brand is not important, but thermostatting is, so you can keep from overheating tiny joints. I used to use a battery-powered job, but I found it didn't provide enough control over temperature, and the tips were too blunt.

2. I never bothered with silver solder; I simply use rosin-core electronics solder, which is very fine, good for control. I use flux on everything--electronic wiring as well as parts assembly. I use tiny amounts of a water-based acid flux (Sta-Cleen, IIRC), and I always clean joints thoroughly afterward with 70% alcohol.

3. 0402 SMDs are not the smallest; there are 0201s, but they're insanely small to work with. 0402s are fine for this project--it's what I used. I just glued them to the backs of the targets, and painted the exposed surfaces with silver paint, followed by flat black. You can get 0402s pre-wired on eBay for decent prices. However, if you solder one terminal of each LED to the brass assembly, you only need to run two wires instead of four. Be mindful of polarity--it's very easy to lose track since the markings are so tiny.

4. Resistors are always needed for LEDs. The values depend on the current rating of the LED given the voltage of the driver circuit. That said, modern LEDs are ofen too bright when run at their rated current; I use a testing circuit I built to determine the best resistor to use: http://davidksmith.com/modeling/project-3.htm

5. I use flasher circuits from NGineering: https://www.ngineering.com/. They have a wide variety of effects circuits, plus they'll custom-program circuits for you--I did this with my flashers so they would ramp the LEDs on and off, rather than have them flash instantaneously (it's surprisingly affordable). The circuits will run on batteries; I believe I ran mine on 2 AAs in series.

Note in my photo, I fabricated a homemade plug-in connector that fits into a micro-socket scavenged from an old VCR. I highly recommend doing something like this, as it allows you to remove the flasher from the layout during maintenance to protect it from accidental damage.

As an aside, I made streetlights using raw 0603 SMDs as the entire light fixture. One leg of the LED was soldered to the arm extending from the pole; I attached #42 solenoid wire to the other leg, and bonded it directly to the back of the pole with CA.



 

[Jesse6669]

Hoods.... madness!   I gotta step up my game.

Thanks for the advice!

- Jesse

[peteski]

Jesse, SMD 0201 LEDs are the smallest ones available (0.020" x 0.010" footprint).  With SMD components the size nomenclature conveniently indicates the components footprint size.  Like SMD 0402 ( 04 02 ) footprint is 0.040" x 0.020", and so on.

If you have the budget to get a suitable soldering iron, there are ones designed for SMD work.  Like DKS mentioned, the battery operated ones do not have temperature control, you have to wait for the tip to heat up every time you need to solder, plus they are to heavy and bulky for the type of precision soldering you will need to do.

PACE is a manufacturer of industrial soldering equipment and they have a soldering iron designed specifically for precision SMD soldering (perfect for any type of soldering very tiny items).  The hand-piece is very small and light, and thy have a wide range of tips available.   It goes from cold to ready in about 3 seconds and of course the tip temperature is adjustable, and highly regulated.


What I own and  recommend is a Pace 8007-0500 Soldering Station, ST50, IntelliHeat, Digital, TD-100.  It has a digital temperature readout, but the one with an analog knob (like shown above) is a bit less expensive.
I got mine from Techni-Tool ( http://www.techni-tool.com/612SO0500 ). They seem to have lowest price, but maybe you could find it cheaper elsewhere.

It is a lot of money, but it is a professional tool which shoudl last you for a very long time, and it would be ideal for the precision soldering you have in mind.  I recommended this setup to @jdcolombo for his decoder installs and he loves it.  Here's his glowing review: https://www.therailwire.net/forum/index.php?topic=40749.msg505458#msg505458. Actually, we had an interesting thread about soldering irons - worth reading: https://www.therailwire.net/forum/index.php?topic=46121.0

As far as solder goes, silver-bearing solder is stronger than lead/tin solders, but not really necessary for most jobs.  Best general purpose solder (for electronic and small mechanical joints) is standard 60/40 or 63/37 rosin core solder.  Those are most common, and most widely available. Using extra flux is absolutely required.  You will probably be using just slivers of solder, so the extra flux will be needed anyway.

[jdcolombo]

And I still love the Pace.  Gotten so used to the precise control that I can’t imagine using anything else.

John C.

[DKS]

And I still love the Pace.  Gotten so used to the precise control that I can’t imagine using anything else.

Well, there are cheaper alternatives. This is the model I own, and it offers digital temp control at a fraction of the cost of a Pace:

http://yihua-gz.com/Products_detail.asp?id=263&sortid=265

And no, I didn't pay $1,000 for it. More like around $50, and it's worked like a champ for around 15 years now. (You can find them for as low as $20!)

 

[MK]

Well, there are cheaper alternatives. This is the model I own, and it offers digital temp control at a fraction of the cost of a Pace:

http://yihua-gz.com/Products_detail.asp?id=263&sortid=265

And no, I didn't pay $1,000 for it. More like around $50, and it's worked like a champ for around 15 years now. (You can find them for as low as $20!)

I have a VERY similar one that I paid about $25 for.  Works amazingly well and you can get heater element part for it should it break.  Takes Hakko tips too.  I've used it for DCC bus soldering to SMD soldering.

[peteski]

Well, there are cheaper alternatives. This is the model I own, and it offers digital temp control at a fraction of the cost of a Pace:

http://yihua-gz.com/Products_detail.asp?id=263&sortid=265

And no, I didn't pay $1,000 for it. More like around $50, and it's worked like a champ for around 15 years now. (You can find them for as low as $20!)

It is not about the digital temperature control.  It is about the shape and overall size of the handpiece.  It is much smaller and thinner than any other soldering Irons I have ever used. and the very thin and fairly short tip cartridge (which is the tip and heating element integrated into a singe unit) make precision soldering much easier.

I wouldn't have thought that the diminutive size would make that much difference, but once I handled one at work, I was amazed with just how much better it was than an average-size pencil-type iron for precision soldering of SMD components.  I liked it so much that I dished out the $300 to get my own.  Seems like John also feels his purchase was worth the price.  You can get by with larger irons of course. It all depends on your needs.

[DKS]

It is not about the digital temperature control.  It is about the shape and overall size of the handpiece.  It is much smaller and thinner than any other soldering Irons I have ever used. and the very thin and fairly short tip cartridge (which is the tip and heating element integrated into a singe unit) make precision soldering much easier.

I wouldn't have thought that the diminutive size would make that much difference, but once I handled one at work, I was amazed with just how much better it was than an average-size pencil-type iron for precision soldering of SMD components.  I liked it so much that I dished out the $300 to get my own.  Seems like John also feels his purchase was worth the price.  You can get by with larger irons of course. It all depends on your needs.

It most definitely is about the temperature control, which is the single most important element of soldering--and it's even more about your budget. Say what you will about the size of the handpiece--in reality, it's an almost trivial aspect of the tool. Your hand can adapt to whatever you put in it. And the one I own is no sledgehammer by any means.

 

[peteski]

It most definitely is about the temperature control--and even more about your budget. Say what you will about the size of the handpiece--in reality, it's an almost trivial aspect of the tool. Your hand can adapt to whatever you put in it over time. And the one I own is no sledgehammer by any means.

I agree that temperature control is vital, but the size of the tip and handpiece also makes a huge difference in the ease of use.  Yes, you can get temperature controlled irons for $20, but they handpieces are more bulky.  Anyways, I made my recommendation (based on personal experience).  Obviously, it is not for everyone (even if professionals use the PACE unit).  To me it was worth every dollar I spent on it.  I have 4 or 5 other irons (I have accumulated over the years), but for precision soldering I always go back to this unit.

[DKS]

I agree that temperature control is vital, but the size of the tip and handpiece also makes a huge difference in the ease of use.  Yes, you can get temperature controlled irons for $20, but they handpieces are more bulky.  Anyways, I made my recommendation (based on personal experience).  Obviously, it is not for everyone (even if professionals use the PACE unit).  To me it was worth every dollar I spent on it.  I have 4 or 5 other irons (I have accumulated over the years), but for precision soldering I always go back to this unit.

Professional what?

[jdcolombo]

https://en.wiktionary.org/wiki/a_bad_workman_always_blames_his_tools 

And pros always use the best tool they can get for the job.  They NEVER skimp on the quality of their tools.  My father-in-law who is a master carpenter and woodworker, taught me that lesson.  He lives in a modest house, drives a modest car, has a 10-year-old small-ish TV set, eats cheaply.  But when it comes to tools, he buys the best one available for the specific job at hand.  He's been at it for 60 years, so I suspect he knows something about this.

John C.

[DKS]

And pros always use the best tool they can get for the job.  They NEVER skimp on the quality of their tools.  My father-in-law who is a master carpenter and woodworker, taught me that lesson.  He lives in a modest house, drives a modest car, has a 10-year-old small-ish TV set, eats cheaply.  But when it comes to tools, he buys the best one available for the specific job at hand.  He's been at it for 60 years, so I suspect he knows something about this.

That's all well and good. We're not all "professionals" here. We're hobbyists. We don't all have professional budgets. And with a little extra skill, we can make do with less-than-professional tools. That's what my main point is. Hence why I suggested an alternative that has served this hobbyist extremely well for years.

[peteski]

Professional what?

Geez!  Professionals who rework SMD components.    Electronic technicians, assemblers.  I used to be one, few jobs ago.

Like I said, I made my recommendation, again, based on personal experience.  You Jesse, and anybody reading this thread can take or leave the advice.

[DKS]

Geez!  Professionals who rework SMD components.    Electronic technicians, assemblers.  I used to be one, few jobs ago.

I don't dispute that you need the best at your profession. I offer more than adequate proof that you can accomplish the same without the need to spend that kind of money.

And by the way, I guess you missed the suggesting I was being facetious. Yikes, I'm outta here.