Ideas about creating this display

[Kaellis991]

I started with the intention of duplicating this KT76C transponder as shown in this link with the (1) 8 digit 7-segment display. https://cessna172sim.allanglen.com/docs/avionics/bendix-king-kt76c/
But after seeing what SimVim cockpit has in the way of an already programmed "layout map" for the buttons, displays and LEDS I would like to try my hand at making the display look like this.

It looks like the way to achieve this would be with (2) 4 digit 7 segment displays separated by a space with some LEDs lighting up letters engraved on the face of black painted white acrylic.

But since I am completely new to making sim panels, I have no idea how to do this.

What are some of the options that might be employed with the 7-segment displays and LEDs to create the display as shown in the attached file?
I know how to mount the (4) digit seven segments, but how would the lighted text be done?

[ame]

I started doing something similar with a Collins CTL radio panel.



My idea was to use a rectangular LED with a laser-printed decal over the top. The decal is drawn as white text on a black background, then printed on laser transparency sheets. The black part is solid, and the white part (text) is clear. About three layers of transparency should be stacked on top of each other because the black is usually not dense enough on a single layer.

Light the LED and it shines through the clear part of the print.

I haven't done much experimentation, but it seems viable to me.

[Kaellis991]

Sounds like a doable approach. I am still leaning towards using white acrylic painted black and then laser engraved to get the text. Not sure how to get the red color.
But what I am at a loss about is how to install individual LEDs for each of the modes. There needs to be a separate and discrete LED for each text display depending on the mode and activated by the rotary switch. Just not sure how those LEDs could be mounted and isolated for each.

[ame]

You can hook up the LEDs to an Arduino pin through a resistor. Typically a 300 ohm resistor will give you a decent brightness.

If you connect the LED (with resistor) from a pin to ground then the LED will light up when the pin is driven high.

If you connect the LED (with resistor) from a pin to 5V the LED will light up when the pin is driven low

SimVim also drives LEDs with a driver chip. The LEDs can be located anywhere and assigned to any function even if they are connected to the same chip. i.e. you can have a bunch of LEDs on different instruments driven from the same chip.

So, you'll have two 4-digit LED modules driven somehow, and five individual LEDs hooked up to five Arduino pins or a driver chip.

[archen]

If you can find a suitable monitor you can also use simvim panel program to display it.

Not sure if there are any displays on the market that can do it.

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[Kaellis991]

If you can find a suitable monitor you can also use simvim panel program to display it.

Not sure if there are any displays on the market that can do it.

Skickat från min SM-N986B via Tapatalk

I have been looking into that also. Vlad over at simvim suggested that earlier today. According to the web site the Raspberry Pi 4 that I have can be connected to my LAN and display the simvim panel for this transponder on a small monitor. I have a 7" TFT HDMI input monitor I have been using with my 3D printer that I think could work. Awaiting confirmation from SimVim.

But if I go the full hardware route my knowledge on mounting the LEDs is sketchy.

Eventually I will determine how to wire the LEDs to the Arduino. But for now I am most interested in the actual physical mounting and the type of LEDs to use. (5mm?)
For each individual piece of mode text, it seems to me that each LED needs to be in its own separate shroud perhaps, for lack of a better term, that keeps the light confined to the individual text display. How could an LED and it's resistor be mounted together? Are there small PCB boards for that? Would I mount the LED in one of these holders and create a 3d printed mounting board with a hole to snap it into? I could incorporate a shroud of sorts. Where and how would the resistor be mounted?

For you experienced cockpit builders this must be one of the easiest tasks...

[ame]

If you can find a suitable monitor you can also use simvim panel program to display it.

Not sure if there are any displays on the market that can do it.

Skickat från min SM-N986B via Tapatalk

I have been looking into that also. Vlad over at simvim suggested that earlier today. According to the web site the Raspberry Pi 4 that I have can be connected to my LAN and display the simvim panel for this transponder on a small monitor. I have a 7" TFT HDMI input monitor I have been using with my 3D printer that I think could work. Awaiting confirmation from SimVim.

But if I go the full hardware route my knowledge on mounting the LEDs is sketchy.

Eventually I will determine how to wire the LEDs to the Arduino. But for now I am most interested in the actual physical mounting and the type of LEDs to use. (5mm?)
For each individual piece of mode text, it seems to me that each LED needs to be in its own separate shroud perhaps, for lack of a better term, that keeps the light confined to the individual text display. How could an LED and it's resistor be mounted together? Are there small PCB boards for that? Would I mount the LED in one of these holders and create a 3d printed mounting board with a hole to snap it into? I could incorporate a shroud of sorts. Where and how would the resistor be mounted?

Well, yes, you could use a monitor and display a picture of the LEDs, but I think that's a terrible idea.

Anyway, you are right. Each LED needs to be in its own shroud. And its own resistor (unless you are using a driver IC which limits the current). If you are using a resistor then you can connect it to either end of the LED:

        R        D
----/\/\/\---->|----

or

---->|----/\/\/\----

Either way, you end up with two connections. One end will be controlled by a chip (Arduino or driver IC) the other end will be common to something (maybe 5V, but usually ground).

Resistors have a physical size, so they need to go somewhere. Either in-line with the LED leads, or on a board somewhere. The LEDs themselves can go on a board, if the position on the board matches the physical location of the indicator, or they can be on flying leads. Or you can put the LED somewhere and have a light-pipe going to the indicator location. It's up to you how you construct this, based on your skill level and parts, tools, and materials available.

Here's an LED in a common 2x5mm package:
https://www.aliexpress.com/item/32888875479.html

I suggest you use the opaque package, not the clear one. If you get the clear one then you'll need a diffuser. There is no magic here- the LED illuminates the decal. The decal is designed so that it looks right when illuminated. Either you copy someone's design or come up with your own. Then the simulator software decides when to turn the LED on.

Even 7-segment displays are nothing more than a group of eight LEDs in a certain pattern with an over-moulded shroud and diffuser.

The Collins panel (in the photo above) is 3D printed, with a hole for the LED to snap into, exactly as you suggested. Again, there is no magic, and nothing really clever. In my design I don't need a resistor as I am using an LED driver chip that does not need resistors.

Experiment with some card, a craft knife, some tape, some glue, some candy wrappers (for transparent coloured film), any LED, some laser-printed artwork, some 3D-printed assembly, some acrylic sheet, some tissue paper (as a diffuser) and what have you. Some people want to spends hundreds of dollars on panels, when literally they are a handful of switches and a handful of LEDs, all of which cost pennies these days.

[Kaellis991]

The transponder I am basing this build on uses 3/16" white cast acrylic. There are three layers. The top faceplate layer, the middle spacer layer and the back hardware mounting layer. All layers were to be painted black. Originally the top layer was going to be the only one to be laser engraved with the text by just removing the black layer of paint exposing the translucent acrylic. Non of that text is to be backlit.

With trying to duplicate the Simvim transponder which is more like the real one, the middle spacer layer would have the additional text for the different modes. Again my initial thought was to do the same laser engraving of the black paint on that 3/16" acrylic middle layer and place the LEDs in the back hardware mount layer or just offset from it and behind. But I can see now that will not work because I expect the light from one of the LEDs will transmit through the edge of the acrylic and bleed into the adjacent engraved text areas and illuminate them.
So the idea of a solid black center spacer with holes for each LED and a thin decal with the white lettering as you suggest would make more sense.
Thanks for your input...

[ame]

Good luck. Whatever works.

While you're at it, why not replace the switch with one that has 45° switch positions, like the original hardware?

Here is a suitable switch:
https://m.aliexpress.com/item/4000700243796.html

Plenty of other vendors have them, but the 30° switch used in the posted simulator project was more widely available at first.