Jump to content

Panel Lighting & Dimming: LED + Avionics


TCUDustoff

Recommended Posts

So while I have everything gutted, I figured its time to address this NOW rather than later.... 

I absolutely HATE the way the Garmin 430 and other Garmin electronics dim.  My experiences as a CFI have taught me that folks seem to love it blaring in their face... or they wear a dang headlamp and the thing brightens up thinking its daylight.  Folks need to spend some time flying with NVGs and then they won't have their stuff turned up so much :) 

Anyways, I always end up putting them in manual mode but, if you forget to put it back on Auto, you can't see it during the day to switch it back!  For my new setup, I am installing the following which all have internal photosensors or the ability to drive via an external rheostat:

  • Dual G5s
  • 430W
  • GTX330
  • PMA7000B

I'd like to drive from a rheostat to give simultaneous, maximum control.  Issue is, from what I read, that these all need an analog dimmer to work.  I was going to put post lights on the remaining four primary instruments, and the engine instruments, but can't find anything that isn't LED and needs a PWM dimmer.  My Google-Fu might be weak, but I can't find a dimmer that either is a) a dual PWM and analog dimmer or b) new, certified post lights that aren't LED.  There are some experimental solutions, but nothing certified.  And, even if I go with Nu-Lights or equivalent solution (which is a separate topic all-together), I'd still need two dimmers to drive the Garmin stuff too.  Anyway to do all this with one knob?  Not a fan of having to get two when they are ~$250 a pop...nor having to drill another hole or have them in separate spots.  

Edited by TCUDustoff
Link to comment
Share on other sites

  • 3 weeks later...

Hi TCU

I used a MaxDim Duo to solve this issue. I know the MaxDims are expensive but their dimming ratios are really good. I have a combination of incandescent and LED lights on the same dimmer and all the lights dim very nicely without flicker or mismatched dimming ratios. I don’t know how they did it, I have a lot of experience in evaluating flight deck lighting (including the 767 tanker NVG), and Seaton Engineering has some really smart cookies working for them. 

  • Like 2
Link to comment
Share on other sites

I made this as an owner produced part to drive RGB LEDs. It’s technically not installed and can be easily removed. I accidentally ordered 50 circuit boards and have the parts to build a couple more. 
 

Id sell the circuit board with a parts list for a build your own kit. Or a fully built one to be (not) installed. 
 

I have my upper center knob currently programmed to do a PWM out that feeds a bunch of things in my panel  

 

FCE1034C-3938-4DE4-AEA2-4473AE329AAA.jpeg

Edited by chriscalandro
Link to comment
Share on other sites

11 minutes ago, N201MKTurbo said:

As long as you don’t crash at night because your lights quit, nobody is coming after you! 
 

If you do crash at night, do it right so there is no evidence. 

Leds aren’t going to make you crash when you have a glass panel. 
 

the glass panel is configured backwards so 0v is bright and full PWM is dim. 

  • Like 1
Link to comment
Share on other sites

We all have the same problem. When I dim the panel lights I still have to go through several things on the panel and manually dim them. An issue is exactly what the OP said, if the devices go on a circuit with a dimmer, then the screen is too dark to see unless you have remembered to undim the lights. It is exacerbated by autodim circuits.  My guess is that some of these devices cannot go on a dimmer circuit because it is outside their certification, the mfr. and/or FAA don't want pilots dimming the lights so low the panel goes out.

Link to comment
Share on other sites

1 hour ago, jlunseth said:

We all have the same problem. When I dim the panel lights I still have to go through several things on the panel and manually dim them. An issue is exactly what the OP said, if the devices go on a circuit with a dimmer, then the screen is too dark to see unless you have remembered to undim the lights. It is exacerbated by autodim circuits.  My guess is that some of these devices cannot go on a dimmer circuit because it is outside their certification, the mfr. and/or FAA don't want pilots dimming the lights so low the panel goes out.

Nearly everything that creates a form of light has a way to control it. 

Link to comment
Share on other sites

Yes, that is not the problem. Some systems can't go on a dimmer, then you have to go through those one by one, find the third or fourth level menu where the dimmer is, and separately adjust the dimmer for each such instrument. Then there are those instruments with internal autodim circuits that are also installed on a master dimmer circuit (rheostat), and then the autodim and the master dimmer don't get along well and you either lose the instrument to black, or the instrument goes the other way, you dim it with the master and then it brightens itself. Frankly, I think the autodim circuits should just go away and let us put them all on a manual dimmer knob.

Link to comment
Share on other sites

What do you have that doesn’t have a dim circuit?

Everything in your airplane that makes light should have a way to control it either via PWM or voltage ref. 
 

the only thing that should be PWM is if you have LEDs. 
 

the Dynon system actually has a voltage dim control input and a PWM output to feed leds if you have them. Not that it helps you...

Edited by chriscalandro
  • Like 1
Link to comment
Share on other sites

I've never been a fan of the new LED post lights and Nulites as the PWM creates a strobing effect which for some of us is very noticeable and borderline nauseating. In addition, a lot of white LED's have a "cold" white balance (i.e. lots of blue) and the red LED's are eye-piercingly monochromatic.

If I recall, Whelen still carries their A350 series of PMA incandescent post lights which are available in limited quantities. They're about $60-70 per light. Light bulbs used are 330 (14V) or 327 (28V).

14V, Long: A350CN06 (white), A350CN07 (red), A350CN08 (clear)
14V, Short: A350CN09 (white), A350CN10 (red), A350CN11 (clear)
28V, Long: A350CN12 (white), A350CN13 (red), A350CN14 (clear)
28V, Short: A350CN15 (white), A350CN16 (red), A350CN17 (clear).

The Maxdim controller, as others here have pointed out, is a pricey but solid solution for controlling. As far as I know there are no dimmers that, using one knob, control two separate circuits - one in analog and one in PWM, but if you're able to get your hands on the Whelen A350 post lights, you won't have to worry about the PWM part anyway.

I myself created my own analog dimmer using a 2N3055 transistor and 1kOhm linear pot with integrated on/off switch and it worked pretty well. If you purchase a dimmer other than the MaxDim or decide to fabricate your own, it is imperative that the potentiometer be a linear one instead of a logarithmic one, since using the latter type will make controlling your lighting feel like controlling your shower water temperature. image.png.8983b6a4dad4e68e8a449465c99acec9.png

Not sure why some avionics techs don't bother with properly hooking up the avionics to a lighting bus. Granted, some equipment (e.g. KX155) don't give you any other option except for the photodiode, but my thinking is, if the equipment gives you the option for a dimm bus and such a dimm bus exists for your aircraft, then use it...

  • Thanks 1
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.