Electronics and components

One very interesting site for ‘cockpit builders’ is opencockpits.com.
This shop offers various modules for building your own cockpit.
One of the nice things is that you can buy them plug and play, or as a kit which saves you some money if you’re a handy with the soldering iron. Building instructions, videos and the software development kit can be downloaded beforehand from their site.

Their I/O cards system consists of a USB card to which up to 4 so called master cards can be connected via parallel port cables.
Each master card has 72 digital inputs for connecting e.g. switches, rotary switches  or rotary encoders and 38 outputs which can be used to drive LEDs.
The master card also has a connector for connecting up to 4 display cards in daisy chain. Per display card you can drive up to 16 7-segment LED displays, so in total up to 64 digits per master card for showing e.g. the aircraft radio frequencies.
They also sell small boards to mount 4, 5 or 6 7-segment display digits so that the wiring of these can be done easily.
I ordered one USB card, 1 master card and 2 display cards to start with.
Soldering wasn’t too difficult but at my first attempt nothing happened when I connected the USB card.
With the friendly support of opencockpits (officially you don’t get support on the kits) I improved my soldering joints and then the USB card was recognized by the computer.

Because there are such a large number of components involved and the budget is limited I started searching the internet for an affordable solution for the switches and so called ‘annunciators’, the small illuminated text panels for various functions.

For most of the components I used the Chinese shopping site aliexpress.com
Switches, rotary switches and LED’s are very cheap there and quality looks acceptable. To save space I ordered mini type switches for most of the functions.
A cockpit also has a number of switches with a guard cap. These caps can also be found on aliexpress, but only for the bigger type of switches (12 mm), so for those I ordered the larger, more expensive switches.

Hard to find or expensive are the concentric (dual axis) rotary switches that are used for a.o. the frequency selection of the communication and navigation radios.
On aliexpress.com there is a shop that sells them for ~ $3 a piece, but without the extra push switch that some functions also require.

The annunciators normally are small boxes with a black or blue front panel with transparent texts that are illuminated in the background by two LEDs. They can be bought in sets for a complete cockpit, but because you need a so many of them it’s quite an investment.

So I decided to go for a different solution.
In Inkscape I designed small black or blue rectangles of 15 x 10 mm with white texts.
The complete designs were uploaded to a web shop where you can have your photographs directly printed on transparent 3 mm plexiglass panels. For a small increase in price you can have the white background paint skipped, which means all the white in the picture will be transparent.
The idea is to glue ~ 1.5 cm long pieces of a plexiglass bar with all but the front painted black behind the annunciator designs in which a LED can be mounted.

For some functions I’m planning to use LED backlighted buttons that I found on aliexpress. These have a removable cap under which a laser printed text with black background can be placed. Some of these buttons in the cockpit can light up in multiple colors. For those I removed the original single color LED in the button and replaced it with an RGB LED so that it can light in multiple colors.

In the design also all the holes for the switches have been drawn for drilling, so that all switches can be mounted in the plexiglass panel.
For the 7-segment displays rectangular holes need to be sawn.

Before having the large, more expensive panels printed I ordered a small panel for a feasibility test: how is the print quality, are the black and blue annunciator boxes dark enough, is the panel thick enough for mounting the switches etc.

This test panel also contains the design of each gauge plate. These will be sawn in rectangles for mounting behind the large plexiglass panel. In that way a sandwich construction of plexiglass plates can be built for mounting small servos for the gauge hands.

On top of the large plexiglass panel various small panels are mounted and the same design is also printed on a vinyl adhesive sticker which will be mounted on top.
This contains all the panel texts.

There are some special cases: the rotary switches for starting the engines are special: you turn them in the left position and when the engines are running after ~ 25 seconds they automatically return to their original position. For this a special servo construction is created.

Some of the gauges have a double hand. For this a special construction is used with two servos, gears and two concentric shafts. These shafts can be bought at modelbrouwers.nl
They have tubes with various small diameters in brass, aluminum or copper that match nicely: e.g. one has 1.8 mm outside diameter, the next one 2.6 mm with 1.8 mm inner diameter etc.

The opencockpits.com electronics order arrived
The opencockpits.com order has arrived
Opencockpits USB card kit
Opencockpits USB card kit
Assembly instructions
Assembly instructions
Assembled USB card
Assembled USB card with one mastercard connected to the right with a PC parallel port cable
Assembled master card
Assembled master card. Inputs and outputs are connected via standard IDE 40-pin flat cables
Assembled display card
Assembled display card
Opencockpits SIOC software input/outputs screen
Opencockpits SIOC software input/outputs screen
SIOC programming
SIOC scripting
7-segment displays and mounting plate
7-segment displays and mounting plate
Alps dual axis rotary encoder
Alps dual axis rotary encoder for frequency dialing
Large switch with guard cap
Large switch with guard cap
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