The Very Last White River and Northern Railroad

[wm3798]

Question from an uninformed N scale electrician...

Is it possible to wire a single resistor to one bar of your "breaker box" to limit voltage going to the whole assembly thereby simplifying the wiring? (rather than a resistor wired to each LED as you're showing here?)

I've done this on some of my interior lighting projects, so I'm wondering if I've found a way to work more efficiently, or if I should increase my contribution to my N scale fire department?

Lee

[LKOrailroad]

Answer from an electronics hobbyist...

Yes, you can use a single resistor with multiple LEDs. This arrangement should only be used when a) all LEDs are the same; b) all LEDs will be on at the same time. The resistor value calculation will be different from a single LED / single resistor. One danger is if one LED should fail you risk losing all of them due to over-current.

LEDs in parallel with single resistor considerations: https://www.allaboutcircuits.com/technical-articles/led-arrays-one-resistor-or-many/

[Edited for clarity]

[Point353]

Question from an uninformed N scale electrician...
Is it possible to wire a single resistor to one bar of your "breaker box" to limit voltage going to the whole assembly thereby simplifying the wiring? (rather than a resistor wired to each LED as you're showing here?)

Are you planning to connect the LEDs in series or parallel?

[craigolio1]

Question from an uninformed N scale electrician...

Is it possible to wire a single resistor to one bar of your "breaker box" to limit voltage going to the whole assembly thereby simplifying the wiring? (rather than a resistor wired to each LED as you're showing here?)

I've done this on some of my interior lighting projects, so I'm wondering if I've found a way to work more efficiently, or if I should increase my contribution to my N scale fire department?

Lee

I done this with every set of ditch lights in my locos. Alan brought you a very valid point in that if one LED fails the current all get directed through the other remaining LEDs. In my case I’m always putting massive resistors in my set ups. Around 10k. So even if one LED failed the others aren’t in danger.

Keep in mind I’m talking about LEDs in parallel. If you are wiring them in series and you lose one then all of them will not light and you have to find out which one.

Craig.

[wm3798]

They would be in parallel.  I see the importance of using the same LEDs per resistor.  I've done some mixing and matching, and in those cases always ended up with multiple resistors.

Thanks for the link.  One day when I achieve complete clarity and lack of distraction, I'll read through all the head-spinning technical jargon and pretend I understand a single lick of it!

Back to the show, with your host DKS!
Lee

[DKS]

Another supplemental entry... When I decided I'd feature a barber shop on the WR&N VIII, naturally I'd need a working barber pole. I spent the better part of a couple of days trying to figure out how I'd make another one. Although I'd done twice before (once on the White River and Northern IV, and again in Z Scale on the James River Branch), this time I had a major complicating factor: there was no place to hide the mechanism inside the building, since the space was wide open and full of windows. I investigated all sorts of possibilities, including incredibly tiny gear trains and other micro-mechanisms. This would involve the tiniest mechanical parts with which I've ever worked in order to animate the smallest object I've ever made, at a time when my skills were rapidly deteriorating.

My solution turned out to be a very direct approach, in all senses of the word. No gears, no friction drive, no mechanism to speak of; instead, the pole would be spun by a short length of 0.005" stainless steel spring wire that attached directly to a geared motor under the sidewalk.

One disadvantage of this approach was that a short length of the drive wire would be visible between the bottom of the pole fixture and the sidewalk; if it was visible enough to be distracting, my plan was to either locate a potted plant beneath the pole, or pose a figure right under the pole to disguise the wire. Another disadvantage was that it was impossible to illuminate.

But the advantages were much more compelling: for starters, it required no precision assembly and alignment of gears or other mechanism parts; I just needed to drill a few tiny holes. Cosmetic advantages included being able to make an incredibly small pole—a classic 1950s Marvy pole is two feet tall and six inches in diameter, and I could come pretty darned close to that (which is much smaller, in fact, than the Z Scale one I built). Plus, I could mount it on a bracket and have it standing freely away from the wall, as many real ones are.

I started with the bracket. Since it's easier to shape material around holes rather than drill holes precisely within a small shape, I drilled two #76 holes in 0.010" thick plain sheet nickel, cut around it, then did the final shaping with a nail buffer. Incidentally, it took three tries to get a proper bracket.

   

   

I was sweating over what to do about the top and bottom caps; I surely couldn't fabricate good-looking parts that small. But after various tiny items from my copious supply of tiny items totally failed to work, I wound up fabricating them from 1/16-inch brass tubing. First, I rounded the edges of the ends, then removed slivers by rolling the tube under a knife, and finally soldered the bits (among the smallest parts I've ever made by hand) to the bracket. The holes filled in with solder, as I expected, but they were easily drilled back out, although I didn't drill all the way through the top cap.

   

Next, I attached the finished bracket to the window trim part. Naturally I bonded it with CA, but I wasn't convinced such a minuscule bond was strong enough, so I bolted it in place with two Scale Hardware 0.5 UNM hex head bolts and nuts, threaded through #78 drill holes. It not only guaranteed the bracket would never come off, but also looked cool—even though the bolt heads scale out at almost five inches across!

   

Finally, I tackled the barber pole itself. Based on past experience, this would be the most challenging part, and it still was. Last time I used decals to make the red and blue stripes, but my decals had all decayed. Instead I used thin strips of Scotch "magic" tape colored with Sharpies. I applied the stripes to a 1/16" styrene rod with a #77 hole drilled through the center (I lost count of how many tries this took to get right, but I think it was about a dozen).



After the stripes were in place, I cut a segment out of the rod to fit the bracket. Then I installed the rod on the bracket using a length of 0.018" stainless capillary tube as the bearing shaft.



The pole is rotated with the 0.005" spring wire that's painted black, just like the window frame behind it. The wire virtually disappears. Each end is simply inserted into capillary tube, one inside the pole, the other mounted on the end of the geared motor.

[DKS]

Can you spot my faux pas? Hint: I'll have to make a new pole.

[Point353]

Can you spot my faux pas? Hint: I'll have to make a new pole.

The stripes run the wrong way.

[DKS]

The stripes run the wrong way.

Correct. And the stripes should appear to descend when rotating.

[wm3798]

I wonder if a short bit of clear styrene rod wouldn't get you closer to illuminating it.  Maybe a fiberoptic filament for the turning rod...  Not sure how you'd get light to it though.  Maybe from above, concealed in a soffit?

Lee

[DKS]

I tried on all kinds of ideas, but they all compromised its appearance somehow--bad enough I have a visible rod turning it. I can live with it not being illuminated.

[LKOrailroad]

How about using 1/16" clear rod (lightly dusted with white paint) instead of white rod. Add a couple (3 if they fit) 0402SMD mounted behind the pole on the bracket?

Mount the pole slightly higher on the wall and place a chair under it to hide the actuating wire.

[peteski]

Actually, when illuminating small items like that white styrene is a perfect material.  It is translucent and it also diffuses light coming from LEDs.

DKS:  I asked you for more barber pole constructions details in the WU thread, and I found the answer here - thanks!

[DKS]

Here's the thing about the styrene rod: it has a stainless steel tube running down the middle of its length, which acts as the rotation bearings top and bottom. Believe me, I've gone down a lot of roads, all of which were dead-ends. I even considered "beaming" light from fiber optics onto the back of the rod through the wall bracket, but there's no space behind the pole inside the building to hide anything, like LEDs or fiber optics. I'm sure there may be a few other tricks I haven't thought of yet, but not many. I think if you saw just how tiny this is in person, you'd realize the limitations. Think: scale 10" x 24"...

[LKOrailroad]

Actually, when illuminating small items like that white styrene is a perfect material.  It is translucent and it also diffuses light coming from LEDs.

I suggested clear (with white dusting for diffusion) because even 0402 LEDs are not going to be small enough to prevent light spillage around the sides. Thinking they would be painted over with just the tiniest of hole left unpainted. Maybe spray paint while holding a toothpick point in place. There will be very little light coming through the tiny hole. DKS will know better since he actually has the pole but that is where my head was going.