# day job v. MRR electronic projects?



## gregc (Apr 25, 2015)

I'm often impressed by electronic projects described here. I know how much time and patience they require.

At least for me, work is challenging enough and I don't have much ambition to test/debug my own stuff at home.

For those of you who are retired from electronics engineering, how active were you at model railroad electronics prior to retirement?


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## gunrunnerjohn (Nov 10, 2010)

Not at all. I got back to it after I retired. Truthfully, for the last few years of my work, I was more in systems design and not really dealing with the nuts & bolts. 

After retirement, I welcomed the chance to smell the odor of rosin core solder wafting from the workbench and projects coming alive (and sometimes smoking) on the bench.


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## jlc41 (Feb 16, 2016)

GRJ, it's not good to let the smoke out, although stuff happens. BTW thanks to your schematic I successfully got my passenger cars illuminated.


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## redman88 (Nov 25, 2015)

jlc41 said:


> GRJ, it's not good to let the smoke out, although stuff happens. BTW thanks to your schematic I successfully got my passenger cars illuminated.




Rerouted some electrical in my train room yesterday. Glad I didn't let the smoke out once I got it working in the whole room.


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## Lemonhawk (Sep 24, 2013)

Similar to GRJ, during my working years with Inertial Navigation Systems, I just sort of kept an ear to Model railroading. Then around 2000 I decided I needed to try DCC, so I built a 5x9 layout using some different type constructions, like one end is only foam, the sides were sort of modular... I never finished it. When I retired a few years back I tore up part of the layout and when I read Joe Fugates article on making your own turnouts, I decided to use all CV ties. I had started a big relay panel and display panel which I finished. Then along came Aurdino and now I'm thinking this will replace all that wiring I did on the relays and make it more universal. So I started working with electronics again, a hobby that I thought was dying out. How wrong could I have been. People ask me when I'll be finished with my little layout and I say never, they just don't understand.


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## raleets (Jan 2, 2011)

jlc41 said:


> GRJ, it's not good to let the smoke out, although stuff happens. BTW thanks to your schematic I successfully got my passenger cars illuminated.


GRJ,
Perhaps you could pass that schematic on once again since I'm very interested in illuminating all of my Walthers Amtrak Superliners, HO scale BTW.


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## gunrunnerjohn (Nov 10, 2010)

I'm not sure which schematic he refers to, perhaps it's the one for my passenger car lighting regulators.









Here's the schematic of that board.


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## jlc41 (Feb 16, 2016)

That's it, but I didn't use the choke or the pot. I went with R1 as a 1k resistor. I did paint the LED's with a sun shine yellow to knock down the brightness. 
My strip LED's were white therefore the paint.


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## time warp (Apr 28, 2016)

I used to incorporate a lot of electronics into my hobby back in the 80's. Barely any now, Work takes too much out of me.


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## gunrunnerjohn (Nov 10, 2010)

Work? I'm retired.


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## time warp (Apr 28, 2016)

:rippedhand:. :laugh:


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## raleets (Jan 2, 2011)

gunrunnerjohn said:


> I'm not sure which schematic he refers to, perhaps it's the one for my passenger car lighting regulators.
> 
> View attachment 224490
> 
> ...


Many thanks, GRJ, but that's WAY beyond my capabilities. Guess my Amtrak passengers will just have to stay in the dark.
Bob


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## jlc41 (Feb 16, 2016)

Hey raleets, it's not that difficult if you can solder. Here's the schematic and parts list. I bought every thing at Radio Shack. I did substitute different parts because that's what the had on hand, and you will need some bread board to mount the parts, which they carry. Give it a try it's only a couple of $$$ hope this helps.
View attachment img126.pdf


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## time warp (Apr 28, 2016)

You tell him J! Don't know till you try!!!! :laugh:


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## CTValleyRR (Jul 26, 2014)

jlc41 said:


> Hey raleets, it's not that difficult if you can solder. Here's the schematic and parts list. I bought every thing at Radio Shack. I did substitute different parts because that's what the had on hand, and you will need some bread board to mount the parts, which they carry. Give it a try it's only a couple of $$$ hope this helps.
> View attachment 224762


Even if you CAN'T solder, it's not that difficult a skill to learn.


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## jlc41 (Feb 16, 2016)

Plus it's all about learning and having fun.


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## gunrunnerjohn (Nov 10, 2010)

raleets said:


> Many thanks, GRJ, but that's WAY beyond my capabilities. Guess my Amtrak passengers will just have to stay in the dark.
> Bob


Made just for you Bob.  You were the target customer when I created this kit.

20100 Passenger Car LED Lighting Kit


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## jlc41 (Feb 16, 2016)

raleets, well there you go, GRJ has a ready fix for you. This is what the look like sorry for the blurry pic. Although they look better than pic.


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## raleets (Jan 2, 2011)

gunrunnerjohn said:


> Made just for you Bob.  You were the target customer when I created this kit.
> 
> 20100 Passenger Car LED Lighting Kit


grjohn,
Well, isn't that just Jim Dandy?
I need to light 10 cars. Five of them are 11", the others are 8" and 9". That means 5 kits @ $175 to get the job done, right?
Now I'll show my stupidity......I'm running simple DC power so how do I get power to the LED lights? Do I need to install those "wiper" wheel sets or do I place a battery in each car and install a switch? When it comes to this stuff I'm pretty dense.
Bob


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## gunrunnerjohn (Nov 10, 2010)

Well, if you're going to use a battery, you don't need a regulator, just size the battery. Also, if you're running plain DC, you probably don't have enough voltage on the track for the 12V strips in these kits.


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## raleets (Jan 2, 2011)

gunrunnerjohn said:


> Well, if you're going to use a battery, you don't need a regulator, just size the battery. Also, if you're running plain DC, you probably don't have enough voltage on the track for the 12V strips in these kits.


Duh? Told you I was stupid........so, please walk me thru what I need to do to get them powered up running plain DC, or are these basically designed for O scale with AC current?
Please keep it simple, and thanks for your efforts,
Bob


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## gunrunnerjohn (Nov 10, 2010)

My lighting runs on AC or DC, but it assumes around 10 VAC or DC at a minimum to operate. If you're running HO with DC, many times you'll have less voltage on the track, so the lights wouldn't light.

You need something like a voltage buck/boost switcher to handle a wide range of track voltages.


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## redman88 (Nov 25, 2015)

gunrunnerjohn said:


> My lighting runs on AC or DC, but it assumes around 10 VAC or DC at a minimum to operate. If you're running HO with DC, many times you'll have less voltage on the track, so the lights wouldn't light.
> 
> You need something like a voltage buck/boost switcher to handle a wide range of track voltages.




Just a thought that came into my head just now. Why not add a relay that will switch the lights on from a battery pack even at low track voltage?


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## gunrunnerjohn (Nov 10, 2010)

There are lots of ways to skin the cat, the first step would be to accurately describe the environment in total so you know which cat you have to skin.


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## redman88 (Nov 25, 2015)

True.


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## time warp (Apr 28, 2016)

I like redman's suggestion:
Battery power the lights, but use a 3 to 5v DC "trigger" to turn the battery power on.
Apply track power, lights on
Remove track power, lights off


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## redman88 (Nov 25, 2015)

time warp said:


> Stupid suggestion maybe:
> 
> Battery power the lights, but use a 3 to 5v DC "trigger" to turn the battery power on.
> 
> ...




That's what I was getting at


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## raleets (Jan 2, 2011)

Yes, I know how to solder. In fact, I'm pretty good at it, BUT the electronics stuff is WAY over my head.
As stated earlier, the Amtrak passengers better bring a flashlight because for the near future they'll be riding in the dark! 
Hmmmm, that could be "interesting", right?
Bob


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## time warp (Apr 28, 2016)

redman88 said:


> That's what I was getting at


I thought so, Made me think. I first thought of a light genie but ruled that out. I'm slow out of the gate last few days.


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## wvgca (Jan 21, 2013)

what about a bridge, to a current limiting resistor, and then across a 2v zener feeding the led / leds ...??
at least there would be operating lights at 3.4V applied .. not many DC locos will run [and pull anything] much below that ..


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## redman88 (Nov 25, 2015)

May be the bridge and a voltage regulator like this

https://www.adafruit.com/products/2166?gclid=CK_FhPi7_M4CFQVbfgodj8UABw


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## gunrunnerjohn (Nov 10, 2010)

I'd probably go with a bridge, capacitor, and the CL2 constant current regulator. Wire the LED's in parallel.


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## time warp (Apr 28, 2016)

Just to clarify, are we talking about the method used to power the LED lights from DC Track Power?

The example that jlc Illustrated of his lighting project is using DCC power correct?

I only mention this because sometimes during these back-and-forth discussions things can get a little confusing, especially to the less experienced ones Among Us.


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## gunrunnerjohn (Nov 10, 2010)

With a bridge rectifier and cap, DC or DCC shouldn't make a difference, other than the voltage on the tracks available to light the lights.

I don't recommend the fixed voltage regulator as a very small difference in LED characteristics can change the operating current in a 3:1 range and easily over stress the LED. For fixed voltages, you need a series current limiting resistor.


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## jlc41 (Feb 16, 2016)

Yes I am running DCC. I think raleets should consider going to DCC it would be much easier to operate his setup.


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## wvgca (Jan 21, 2013)

gunrunnerjohn said:


> I'd probably go with a bridge, capacitor, and the CL2 constant current regulator. Wire the LED's in parallel.


The CL2 is a better solution for a lot of applications .. the only reason I mentioned the zener was to get a lower 'turn on' voltage for DC control ... it's crude, but with a pale yellow led there should e light at around 3.4V, higher if using a white led..

most other [and more refined] solutions commonly used for AC or DCC can sometimes need a minimum 6.5V input, or better, .. fairly quick movement when applied to a DC loco


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## Lemonhawk (Sep 24, 2013)

The CL2 is an easy to use device as only 2 terminals are used. Voltage in and 20 ma out. Since it outputs 20 ma, putting a resistor in series with the LED only causes the need for a higher input voltage as the CL2 strives to generate the same 20 ma. You can put a resistor in parallel with the LED to divide the 20 ma between the LED and the resistor. CL2's come in SMT form so you they can be very small


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## Shdwdrgn (Dec 23, 2014)

Miss a day, miss a lot... wow, long thread!

FWIW, I have a degree in electronics from the now defunct ITT, however I've never worked a day at an electronics job. I'm a computer guy, but I took the course so I *could* build my own circuits. More experience would go a long ways, but I make do...

John, looking at your passenger car pics, one this stands out to me... paint the inside of the car flat-black before adding windows! 

Regarding the discussion of the LED circuit, instead of a battery why not use supercaps? They recharge quickly and hold plenty of juice for a few LEDs. I wonder if you couldn't just put one in parallel with the rails? Let's see how my ascii art is...


```
----------     diode    (+) ------*------/\/\/--- L
track          bridge           [cap]             E
----------    rectifier (-) ------*-------------- D
```
OK it's not pretty, but basically you want a rectifier to ensure the polarity from the track, then put a supercap across the input voltage, add in an appropriate resistor, and an LED across the ends of the wires. I *think* this will allow the cap to recharge when there is track power and supply voltage when the track power cuts out. Also the rectifier should protect the cap against someone shorting out the wheels.

John, what do you think? Is it that simple?


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## raleets (Jan 2, 2011)

grjohn & all other "techie" guys,
My SINCERE appreciation to all of you for your efforts in trying to help me illuminate my passenger cars.........however, 99% of what you guys are saying is Chinese to me.
My soldering skills have allowed me to wire my entire DC layout, including a few toggle switches, but building circuit boards with electronic parts and pieces is WAY beyond my capabilities.
What's that old Clint Eastwood saying...."A man must know his limitations" or something like that?
My Grandpappy once told me "A smart man is a man who knows what he doesn't know". Makes perfect sense to me!
Anyway, thanks again for all your suggestions. Looks like my passengers will just have to stay in the dark for now.
Bob


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## Shdwdrgn (Dec 23, 2014)

@raleets -- don't sweat it, creating the circuit is the hardest part, and folks around here are willing to help you do that part. As for soldering together a circuit board, there's an easier way... There's this stuff called 'perfboard' which is a circuit board with a grid of holes and individual copper pads around each hole on the back side. This is how many of us start out with circuits... you put your components anywhere on the board that makes it easy to hook them up. In a simple layout like what I tried to explain above, you would simply lay your components in a line and bend over the wires from one part to reach to the next part. Solder the pads as needed, and poof, you have a circuit! Just cut out the amount of the board that you actually use to keep it small.

Check out this web page, they have a great little tutorial for using perfboard...
https://itp.nyu.edu/archive/physcomp-spring2014/Tutorials/SolderingAPerfBoard


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## gunrunnerjohn (Nov 10, 2010)

Shdwdrgn said:


> Regarding the discussion of the LED circuit, instead of a battery why not use supercaps? They recharge quickly and hold plenty of juice for a few LEDs. I wonder if you couldn't just put one in parallel with the rails? Let's see how my ascii art is...
> 
> 
> ```
> ...


Well, one issue with that configuration is you have a huge inrush current when the cap starts to charge from totally discharged, it'll look like a short circuit. You'd probably want at least a 100 ohm resistor in series with the SuperCap so that doesn't just yank the power on the track down. Also, the track voltage can easily exceed the max voltage of a SuperCap, so you'd have to have several in series. With the series configuration you'll also have to provide load balancing for the SuperCaps so they don't charge unevenly and exceed their voltage ratings. Finally, you still have the issue of controlling the current to the LED(s), the SuperCap just gives you buffering of the voltage to keep the lights on with power interruptions, I don't see how they're solving the basic issue of controlling the power to the LED(s).


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## raleets (Jan 2, 2011)

jlc41 said:


> Yes I am running DCC. I think raleets should consider going to DCC it would be much easier to operate his setup.


Many thanks for your suggestion, but raleets has NO intention of going to DCC.
Model railroading is simply a fun-filled "winter hobby" for me and a chance to relax in the garage fiddling around with a nice layout and run some model trains 'round and 'round.
Switching, operations, and all that stuff hold no interest so DCC isn't even remotely attractive to me.
In truth, creating cool scenery and animations are my passion in this hobby. The actual running of trains is a distant second.
While I totally appreciate sophisticated electronics, it's not something I can't live without at this time.
Just my .03 cents,
Bob


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## raleets (Jan 2, 2011)

gunrunnerjohn said:


> Well, one issue with that configuration is you have a huge inrush current when the cap starts to charge from totally discharged, it'll look like a short circuit. You'd probably want at least a 100 ohm resistor in series with the SuperCap so that doesn't just yank the power on the track down. Also, the track voltage can easily exceed the max voltage of a SuperCap, so you'd have to have several in series. With the series configuration you'll also have to provide load balancing for the SuperCaps so they don't charge unevenly and exceed their voltage ratings. Finally, you still have the issue of controlling the current to the LED(s), the SuperCap just gives you buffering of the voltage to keep the lights on with power interruptions, I don't see how they're solving the basic issue of controlling the power to the LED(s).


grjohn,
Now that exackerly what I'm talking about when I say you folks speak Chinese......NO disrespect to the Chinese, but the electronic gibberish is beyond my mental capabilities, and I readily admit it. 
A huge tip 'o the hat to you folks who have mastered all that stuff. :appl:
Bob


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## wvgca (Jan 21, 2013)

Shdwdrgn said:


> Regarding the discussion of the LED circuit, instead of a battery why not use supercaps? They recharge quickly and hold plenty of juice for a few LEDs. I wonder if you couldn't just put one in parallel with the rails? Let's see how my ascii art is...
> 
> 
> ```
> ...


if you put a 7805 or similar between the bridge and the cap, then you can get away with one double stack super cap [5.5v] .. still will need an inrush charge current limiting resistor in series between bridge and cap


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## time warp (Apr 28, 2016)

raleets, Here's my high tech: Metal wheelsets, contact wipers and screw base bulbs for lighting in my passenger cars, plus I have silhouettes in the windows!

I totally admire and respect the electronics, but I'm an old timer. I'm happy.


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## Shdwdrgn (Dec 23, 2014)

John and wvgca, yeah I forgot about the difference in voltage. So yes, something to bring down the initial voltage to a 5v level makes sense, then choose the proper resistor to feed the LED from that 5v source. There are some pretty tiny DC-DC regulators on ebay that would avoid the heat output of the 7805, and the resistor in line with the supercap makes sense as well.

Considering the low intensity of the lights inside passenger cars, I bet a small supercap could run a few LEDs for several hours, maybe even days, and with the right parts this project could easily be built for a few dollars per car. Of course the one issue I can think of with the battery backup power here is that when you turn off your train set power at night, the passenger cars will continue to glow for a long time!


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## wvgca (Jan 21, 2013)

Shdwdrgn said:


> Of course the one issue I can think of with the battery backup power here is that when you turn off your train set power at night, the passenger cars will continue to glow for a long time!


You can get latching switches that turn on or off by passing a magnet over them, these can be mounted inside the car roof panel, or just a small slide switch underneath works also ..


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## gunrunnerjohn (Nov 10, 2010)

Of course, with a powered rail, the supercap is really overkill with nothing much to recommend it. It's not normal to want the car to run several minutes of lighting after you remove power. In truth, the bridge, a 330uf 35V cap, and a an LDO regulator. The TI LP2950-50LPRE3 is a 100ma regulator in a TO-92 package, perfect size for an HO car. Use a small bridge rectifier and cap and you have your 5V supply. A small series resistor to limit LED current and you're set.


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## jlc41 (Feb 16, 2016)

raleets, I understand your like of working with scenery and details. I for one enjoy that aspect of the hobby also. It seems there is always something more to add to make the scene more interesting and realistic. Enjoy the hobby I know am having a lot of fun with my layout.


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## redman88 (Nov 25, 2015)

Just saw this on Facebook. 

https://www.facebook.com/voltera.io/


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## gunrunnerjohn (Nov 10, 2010)

redman88 said:


> Just saw this on Facebook.
> 
> https://www.facebook.com/voltera.io/


OK, you got me. What was the purpose of that?


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## redman88 (Nov 25, 2015)

gunrunnerjohn said:


> OK, you got me. What was the purpose of that?




By the looks of it's for applying solder paste


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## gunrunnerjohn (Nov 10, 2010)

Actually, I went and looked again, they're applying conductive material to make a PCB. There would be no point in laying down solder paste on a bare board, the heat would simply destroy it without conductive material for it to stick to.


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## wvgca (Jan 21, 2013)

gunrunnerjohn said:


> OK, you got me. What was the purpose of that?


 I have seen the product on the web before, makes pcb's on blank substrata with conductive paste, can also apply solder paste .. machine itself is little over $2K, conductive ink is $100 to do [they say] about 85 small pcb;s, solder paste is $50 or so ..
It's a neat idea, but well out of my budget or toys like that ....


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## gunrunnerjohn (Nov 10, 2010)

Yep, it looked like an expensive toy to me. I'd never have occasion to print a PCB like their demo, those close pitch parts I leave for the board house to assemble. I have a self-imposed limit of .05" (1.27mm) lead spacing for parts and 0603 and larger sized discrete components. I can handle those, the smaller stuff is just too hard to deal with by hand. Anything I can't build a prototype for I'm not interested in going into production with.


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## redman88 (Nov 25, 2015)

gunrunnerjohn said:


> Yep, it looked like an expensive toy to me. I'd never have occasion to print a PCB like their demo, those close pitch parts I leave for the board house to assemble. I have a self-imposed limit of .05" (1.27mm) lead spacing for parts and 0603 and larger sized discrete components. I can handle those, the smaller stuff is just too hard to deal with by hand. Anything I can't build a prototype for I'm not interested in going into production with.




Looked like they were showing off the different sizes it could do


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## gunrunnerjohn (Nov 10, 2010)

Yep, just doesn't look like anything that would be all that useful to me. That's for much larger companies that can afford to keep the materials and machine on-hand for it.


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