Showcase Miniatures - redesigned signal heads for LEDs

[peteski]

Is it an RYG chip or just bi-color with a mixed yellow?

True RYG with 3 LED dies.  If it was just bi-color you would only need 2 wires in the bundle (not 4).

[peteski]

As I was stuffing the little hairs down the tubing, I was thinking-through your idea about separating the common on each and using the mast. The issue then becomes one of soldering the ultra-fine wires to the top of the mast given the assembly order of all the fine bits. Doable, but has perils. In the end I think I'm more comfortable with terminating all the electrical fiddly-bits separately from the mechanical considerations. We'll see after I get a couple under my belt.

No need to solder all leads at the top of the mast.  Just pre-tin a spot near each opening for the wire bundle then tack-solder the common wire at that location.  If done quickly, it will not affect the other targets. Even if you already threaded the wires through the mast, their insulation can withstand soldering temperature. I managed to solder the common lead of each bi-color LED in this prototype I made long time ago without damaging anything.  I also soldered the photo-etched ladder parts to the mast.  It is a very solid assembly.

[railnerd]

The signal heads are now up on the showcase site— basic change is to change the casting to allow the LED to be inserted, which requires a new etched back plate be installed:



Looks like the LED is a "side firing" model.  I plan on ordering some replacement heads and LEDs for my unbuilt signals next week.

-Dave

[Sokramiketes]

True RYG with 3 LED dies.  If it was just bi-color you would only need 2 wires in the bundle (not 4).

Not always true. Some "bi color" LEDs have separate anode and cathode connections for both colors.

[C855B]

Here you go... I jumpered a quick test on the bench. These are driven @ 4mA.

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In-signal tests will have to wait for the new-style heads.

[jagged ben]

Not always true. Some "bi color" LEDs have separate anode and cathode connections for both colors.

And some have three leads...  A common cathode or anode and separate leads for whichever is not common.

[C855B]

Not always true. Some "bi color" LEDs have separate anode and cathode connections for both colors.

And some have three leads...  A common cathode or anode and separate leads for whichever is not common.

Both true. The early bidirectional 2-lead versions were a major b!tch to design into TTL circuits. Polarity reversal had to be handled with external components because there was no such thing as a hi-Z state in TTL gates. The four- and three-lead versions were introduced to solve the dilemma.

Geez... TTL. Gates. Sure as heck am dating myself. 

[sp org div]

Hard to tell much about LED color or brightness from a photo, but those images make it look good.

Really nice looking models, but I wish they were plug and play!  Got to hand it to Dan Crews there.

Interesting choice of the short hood over SP's more typical long hood design...  I think it would have been cool to file to length (pots), since assembly is required anyhow... maybe a future addition? 
Even with the small etching image provided, I think I can see they got the lip around the edge of the background too. 
Will be interested to hear how she cleans up without a lens, or maybe they got it so the LED comes up flush, so no fiber needed.
She's a beaut!

[C855B]

With a 3V source and 680 ohms, I'm under-driving it, so don't take the brightness in the photos as gospel. That's 4mA across the resistor, but obviously doesn't factor the ~3V the chip itself draws. The instructions use 3mA @ 8V (1500 ohms) as their example, but that's the only indication of recommended values. I guess I need to rummage around in my electronics junk for other resistors.

SP long hoods are on a small fret of brass parts that come with the signals, while the main parts fret is stainless. I had this conversation with Joe @ Showcase way back when they first introduced the signals, and he said the short hood is prototype SP, too, and linked to a picture of one on the Siskiyou line. I have mixed feelings about the as-cast short hood, because it needs to be reamed out anyway to look right. I just wish... probably should suggest... they expand the brass fret to include the curvy GRS hood, too, which is mostly what you see here in Illinois. The few that are left, anyway (they're goin' fast!).

I'll let you know about the fitment when the heads get here. Judging from the dimensions of everything as parts, I suspect we still want to apply a dab of something to form a lens.

[ryan_wilkerson]

I lost track of this thread...I like how things have developed. When I get back to my signals, I will need to get replacement Showcase heads for the dozen or so kits I have.

Here is a photo of both size hoods...1:1 scale.
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[Smike]

These are the ones that are pushing me to finally start putting together a signal system. I'm going to order a few, but starting from scratch and wish there was a wire a LED signal system for dummies. Any suggestions on good sources for setting up a signal system (wiring (which resistors to get wire connection options) and design of the system, (such as block occupancy detection etc.)