Most of the panels in my cockpit are backlit by placing individual 3mm Green LED's behind the text. To minimise hotspotting I used groups of three LED's wired close together, behind each piece of text.
Another easier method to backlight the panels is to use LED strip lighting. With strip lighting you cannot choose exactly where you want to put each individual LED, but to minimise hotspotting you can mount the LED strip further away from the panel, so the light spreads evenly. This works well in some panels, however large switches and rotaries will cast a shadow on the panel, so some text may be blocked. A few of my panels, like the ARC-210, use a combination of both methods.
Here is an example of hotspotting. You can see how 'channel' is brighter where the LED is in the centre, behind the N, but darker around the edges. This can be combated by putting more LED's behind each block of text.
I use normal cheap 3mm Green LED's. These are inserted into the 3mm holes cut in the bottom layer, then wired together using solid core wire so the circuit retains it shape when it is removed from the panel.
This is how the LED's are mounted in the panels. The 3mm LED press fits in a 3mm hole in the rear panel, which is solid black so no light bleeds out the rear. The middle panel has a pocket drilled or engraved in it, and is translucent and diffuses the light. The top panel is painted solid black and engraved with the text.
Almost all of the LED's are wired in groups of three, connected in series, with one 100 ohms resistor. Keeping this format on all panels makes the lighting similar throughout the entire cockpit.
There are only a few exceptions on panels where I couldn't physically fit three LEDS, so where 2 LED's are needed its a 270 ohm resistor, if one LED is a 470 ohm resistor.
The groups of three are then all connected in parallel to the single power source.
Here is the rear panel of the Radio Stack ready for backlighting.
Here is the backlight loom wired up. Groups of three wired in series, all connected in parallel, sharing a single connector for the power source. I use solid core wire, so the circuit retains its shape when removed from the panel. Most of the LED's are connect with their own bent legs.
The LED's and entire circuit are retained in the panel using Vinyl sheet. Nothing fancy, it's the same stuff used in sign-writing or to wrap a car. It is self adhesive, stuck on and then hit with a heat gun to mould it in place. It is easily removed, and non conductive so it prevents the circuit shorting out on anything else mounted to the panel.
Test fitting the hardware in the panel. Remember this when connecting up your circuit, as the wiring needs to be run so it doesn't foul on anything.
The radio stack with the top panels on. The LED's illuminate the text engraved in the black paint on the top panel.
I used cheap eBay 5050 LED Strip lighting to cover large areas that needed backlighting, the main example being the keypads for both the Contol Display Unit (CDU) and the Up Front Controller (UFC).
I did this as I couldnt find any cheap tactile buttons that had LED's in them, nor could I be bothered wiring up an individual LED for each button. There are 103 individual keys in the cockpit.
The LED strip works well, as long as you are able to mount it away from the rear of the panel so the individual LED's on it don't hotspot behind the text.
LED Strip lighting cut to lengths, wired up and ready to go on the CDU. The strip is self adhesive, and stuck to an acrylic sheet that is on top of the PCB. This entire assembly is then set off the rear of the front panel with 5mm motherboad standoffs to avoid hotspotting.
The top panel and keys in place. Hotspotting is still visible around the keypad border, but its much better than what I would have been able to acheive using single LED's.
LED Stip on the UFC keypad. You can see the brass motherboard standoffs that hold the strip away from the rear of the engraved front panel.
UFC front panel fitted.
I also used small lengths of LED strip for the analog gauges in the cockpit.
Top cover on the gauge. I choise to do the gauges with white LED strip just to break it up a bit. I was sick of NVIS green...
Power for the backlighting circuit is from an Antec CP-850 Computer power supply that is mounted in the left console and powers the entire cockpit. That PSU was remove from an old gaming PC I had, and is an oversized model that only fit in a select few Antec cases. It powers the entire cockpit, so there is only one power plug for the entire cockpit.
One of the 12V rails of that PSU is dedicated to the backlighting. It is connected to a two PWM dimmers, one for the console lighting and one for the gauge lighting. Both of those PWM dimmers are then connected up to terminal blocks, and all the panels are connected to thos blocks.
With every panel on full brightness, a multimeter tells me the circuit draws a max of 8 amps.
The PSU rail can support up to 22 amps, so plenty of headroom.
These are the LED Dimmers I mounted in the console to dim the backlighting. I opened up the casing and extended the wiring on the potentiometer, then mounted the it in the lighting panel.
The Antec CP-850 mounted in the front of the left console. All the wiring was cut to length then connected to terminal blocks so it can be easily distributed around the cockpit. The intake fan in the console floor gives it some airflow.
The Power supply mounted in the console. The hot air exhausts out of the console, just like if it were mounted in a PC.
This video shows the basics of my panel design.
Skip to about 9:10 where the backlight content begins
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