Learned a couple lessons while building a fascia control panel for my Tortoise actuated turnouts.
First, the long and short terminal pins of a bi-polar LED are not consistant as to polarity, or at least the ones I’m working with. This discovery would have been way worse if I’d already busted out the solding iron.
Second, Found that applying a heavy coat of polyurethane to the backside of 1/8" Masonite/hardboard stiffened the material just enough to make installing the LEDs into the plastic press-in holders all but impossible without back facing the holes.
Hmm, most two-lead bi-color LEDs I have don’t have different lead lengths, both are cut the same. Unlike a regular LED where it does matter, for the bi-color LED it only matters for which color is displayed with which polarity.
Guess I don;t follow on the LED holders - most of the ones I’ve seen are only good up to 1/8" thick panels, do you mean the extra coat of poly made the thickness too great? Kind of stinks, but they do look much better even witht he little plastic ones, vs just sticking the LED in the hole by itself. The fancy metal ones usually have a nut on the back like a switch and can be used it fairly thick panels, but they cost a lot more and are relatively huge and take up too much space.
When I’m working on turnout controls and indicators I usually make sure the toggle and points agree ( I like to have my toggle switches face down in the “normal” turnout direction so I can quickly reset everything to the main routes by flipping all the toggles down) then, before soldering I touch the pigtails previously soldered to the bicolor LED leads and see if I’m getting a red or a green as appropriate, then get out the solder and shrink tubing…
Those fancy, and expensive, metal LED holders have a downside. The LED sits loose in the metal housing and can protrude forward, slightly hanging out of the metal housing. I have never figured out how to secure the LED tightly in the metal holder.
The 3mm bi-polar LEDs I’m using do have one lead longer than the other, though not by much. Probably just the way they were manufactured.
Your thought about the poly increasing the thickness of the board got me to thinking. Before getting started with the panel I test fit a holder and LED into a scrap piece of unsealed and unpainted board, worked fine. But then I roller painted the smooth face of the panel board with a generous coat of primer and two color coats of acrylic latex before adding the coat of poly to the backside. Upon measuring the finished panel board I found the paint and sealer had increased the thickness by nearly .025, surely enough to make installion of the LEDs into the holders impossible.
I found my bi-color LEDs consistent as to polarity regarding the longer vs shorter lead (mine were from All Electronics). I used 5/64" aluminum panel for the face. The LEDs fit nicely (friction fit) using only one part of the two-part plastic LED holders inserted into the aluminum control panel hole.
I think the metal bezels are supposed to have plastic inserts that keep the LED in place. They are expensive, at Radio Shack, but I saw some eBay seller with 100 for $79. But, I think they are too large and look odd for a control panel on masonite.
If the total thickness is too great for the palstic ones - use them anyway, but secure with a drop of white glue. It will keep them from falling out but if you press they will pop right out. Friend did that with 3mm LEDs with no bezel in his masonite fascia. Slightly undersize hole but easy to press fit in because of the fuzzy edges of the holes, drop of glue on the back and they won;t fall out. Not as nice as having the bezels though.
Paul, The inconsist leads with the bi-polar LEDs I’m using may have to do with them being low quality.
Randy, I was able to get the LEDs to fit snug into the plastic holders by carefully back facing the holes in the panel board with a countersink bit. Had to pull all the toggles out first to make room.
Randy, the metal LED holders from Radio Shack do have a small rubber insert with two small holes drilled through it for the LED legs to slip through. It looks like an eraser on the end of a pencil. As you say, the purpose is to keep the LED legs separate, and it does do that, but the LED does lean sideways and slip forward. Not sure what to do to prevent this slippage.
When using the black plastic LED holders, you need to measure and drill a properly sized diameter hole that the LED will protrude sufficiently through the opening once inserted into the little plastic holder. If the hole is not sufficiently drilled, the LED holder will fit through the opening, but the LED will barely reach the surface of the control panel.
As they are manufactured, the short lead is - (or ground) and the longer lead is +.
If you salvage LEDS from Christmas sets then they have been clipped. So I look at the Annode and the Cathode directly. The bigger “flag” is supposed to be - but I have found that that tell tale is not consistant.
I’m not getting all this + and - stuff on LED leads, as I’m just putting together a new control panel and haven’t gotten to that point (the electrical part) yet. I do, however, have LED’s that I’m planning on installing in the board. The LED’s I have, have a slight lip or flange around the base. I’m thinking that if I just drill a hole the diameter of the “bulb” portion of the LED, that the flange will be a place where a small drop of glue will hold the LED in place, Right?
BTW, I’m surprised that polarity makes a difference in the way LED’s should be connected. I’m writing this as a very rank amateur who knows almost enough to be dangerous about electrical and electronics; please excuse my ignorance.
I was thinking the same in regards to a press fit hole for my panel LEDs, but realized that my hardboard fascia does not lend itself to clean edged reliable sized holes drilled into it. Also prefer the looks of the LED holder bezel. I’m guessing that if a suitably stable material like alum. or plexiglass were used for a panel a press fit hole could be acheived, maybe even tight enough to not need glue.
An LED has an anode and a cathode. Electricity will only flow through it in one direction. A bi-color LED has two LEDs in a single mount. One lead is one color and another lead is the other color. The third lead is the common.
Yes, Peter, I’ve decided to go with 1/8" cabinet grade alder wood. I should get a decent hole for the press mount. Just a touch of CA glue should hold it.
If you are using the chrome bezel subminiature LED’s from Radio Shack part# 276-069 for the green ones, they do not come out, they may move slightly, less than 32nd. But I know for a fact they will not come out, unless you break it. The ones I’m referring too have a 7/16 threaded metal shaft, two leads coming out of the bottom, short lead negative, with a nut and lock washer.
Just a thought, but maybe a glue less permanent than CA in case a LED might need to be changed out. Of course the 5mm ones I used on a previous control panel lasted beyond the life of the layout, 24 years, probably would have outlasted me.
You could use Hob-e-Tac from Woodland Scenics or something similar. It will hold them in place and you can remove when you want. I have a brakeman mounted to the front steps, on a SW9 switcher, just has a drop, on each foot and he hasn’t fallen off yet in 5yrs. [:D]