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Screen light too bright
#1
I'm running a standard tiny pilot built by Sean. The lights on the Nokia screen are incredibly bright and ruin night vision for the watch keeper. I covered the screen with black tape up to the very edges of the display area and put red transparent plastic over it but it is still way too bright. Blindingly bright when you have been in the dark long enough to develop good night vision.

Ideally, is there any way to adjust brightness in software?

Or to add a knob to adjust it?

Failing that, is it practical to cut off the LEDs and replace them with dim, red ones?

Normally any kind of white light at night is forbidden on my boat, red light only. Adjustable, dimmable red light would be best. For effective use at night it needs to be really, really dim ,and all the light directed at the screen.

Has anyone come up with a solution or ideas for this? I'm reluctant to start cutting the LEDs off the display without knowing whether that will upset it somehow!
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#2
(01-06-2020, 08:12 PM)syohana Wrote: I'm running a standard tiny pilot built by Sean. The lights on the Nokia screen are incredibly bright and ruin night vision for the watch keeper. I covered the screen with black tape up to the very edges of the display area and put red transparent plastic over it but it is still way too bright. Blindingly bright when you have been in the dark long enough to develop good night vision.

Ideally, is there any way to adjust brightness in software?

Or to add a knob to adjust it?

Failing that, is it practical to cut off the LEDs and replace them with dim, red ones?

Normally any kind of white light at night is forbidden on my boat, red light only. Adjustable, dimmable red light would be best. For effective use at night it needs to be really, really dim ,and all the light directed at the screen.

Has anyone come up with a solution or ideas for this? I'm reluctant to start cutting the LEDs off the display without knowing whether that will upset it somehow!
Just an idea:
Carefully disassemble the display, replace the blue LED's by red ones, carefully assemble the display again.
And put a small potentiometer in series with the backlight connection.

And let us know if it worked!
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#3
(01-07-2020, 05:58 AM)It Paradyske Wrote:
(01-06-2020, 08:12 PM)syohana Wrote: I'm running a standard tiny pilot built by Sean. The lights on the Nokia screen are incredibly bright and ruin night vision for the watch keeper. I covered the screen with black tape up to the very edges of the display area and put red transparent plastic over it but it is still way too bright. Blindingly bright when you have been in the dark long enough to develop good night vision.
For the time being, go low-tech with:
Filter Film Cut to Size of Screen

Or something like that!  Having been a navigator in the Navy, I get where your coming from!
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#4
You could replace the leds with a different color, but it is a surface mount led and difficult to solder.

Also possible to replace the 10 ohm resistor (R4) on the tinypilot hat with something with more resistance. Try 30, 50 or 100 ohms, it should dim the light. Cutting or removing it will have no backlight which is maybe better?

The next version of the hat has an onboard arduino which (among other tasks) can adjust the backlight brightness. There is also a photo resistor to turn the light off if it is not needed.
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#5
Thanks Sean, Sounds like a 200ohm pot in series with the original resistor might work but I can't get one here. I do have an assortment of resistors on board though. I'll try putting in a 100 ohm and see how that goes. Doesn't running LEDs on low voltage kill them pretty quick though?

New hat sounds great, will it be a plug and play upgrade for older tinypilots? I noticed the 5110 screens are available with red led light, maybe easier to swap the whole screen than change the leds. It would be great if you could source 5110 screen with red light to use from the start on future tinypilots. White light has no place on a boat at sea and can be dangerous if the watchkeeper can't see properly.

Wdee: that was our first idea. We managed to find a red plastic document folder in the canaries and cut bits out to stick over the display. The white light is so bright that the screen becomes unreadable if we use enough layers of red film to reduce the brightness significantly.
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#6
The nokia5110 is also a bad screen because of the steel case rusts and if magnetized can distort the magnetic field. There is also the contact problem with these displays. I have another display which doesn't have any of these problems but it has different problems.

I will look for red led ones, but isn't blue even better? I had a few in blue but more than 90% are white. I think the easiest option for now is tape and light filters.
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#7
Considering pretty much all boats have red cabin lights fitted for night sailing and our tablets running Android use apps like Twilight to dim then at night, which also tint the screen red, I think red is the right colour.

Inevitably the red lights on a boat will affect the crew's ability to see port side lights a bit but at least it's only one primary colour so the blue and green sensors in our eyes are unaffected and we retain at least 2/3 of our night vision. If you have lights of other colours on board then your night vision will be affected across the whole spectrum.

It's a real annoyance that some instrument companies use other colours but generally red is the standard night lighting at sea.

Fun fact: sailors (including but not limited to pirates) were often portrayed with an eye patch. generally they actually had two eyes and the guy with the eye patch was the navigator. The eye patch they wore was so that they could retain night vision while working on the chart under candle light. On deck they would lift it up and still have night vision in one eye which had been covered. Try it, it still works and is a more important technique than ever now that we all have tablets and laptops at the chart take.

Our pypilot is mounted outside at the helm so unfortunately an eye patch doesn't help. It lights up the whole cockpit.
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#8
The RPi can't PWM the backlight pin?
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#9
the backlight draws very near the limit for what a raspberry pin can drive.
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#10
After a lot of experimentation I found that 100 ohms is much to little, didn't make much difference. Eventually I found a 10k resistor gives a safe light level for night sailing with the white backlight. For dawn/dusk or with a red filter on top then a 3-5k resistor is sufficient.

I took off the original resistor from the tiny pilot board and soldered wires on instead so I can change the resistor easily.

When I can obtain one then I'll replace it with a potentiometer so I can adjust it to suit the ambient light level. I think a 20k potentiometer would give the best adjustment range, or a 10k pot might be enough with a red backlight.

Maybe you could include a 20k pot in the next iteration of the tinypilot, with an external knob? It's a really important safety consideration not to damage the crew's night vision and the cost would be minimal. If you can find 5110 screens with red LEDs too then doing both would be even better.
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