Quote from Hangar45 Admin on December 13, 2017, 6:42 am

(Original thread started on 05-20-12 by Will Sasse)

Has anybody successfully managed to dim the 389 replica switches using the Crew Lights panel? I have PWM's (Pulse Width Modulators) for the task.

 

I would like all LED's to be dimmed on the appropriate dimmer, both interfaceable and non-interfaceable. This requires that they be on a common power rail via the PWM - just one does the whole instrument panel.

 

It's easy for the non-interfaceable as they are switched via the appropriate switch & can be powered through the PWM to a common rail.

 

The issue is the interfaced switches, with the LED's activated depending on a state of FSX via an I/O board (ie: FDS SysBoards), and receiving power via that I/O board.

 

One way I can think of at the moment is to use relays, lots of relays! One per interfaced LED. So that when the I/O card commands the LED on, it triggers the relay which is powered from the PWM via a common rail, and vice-versa. This would require a relay with a 2.8-3.0v (direct or using resistors) output triggered by a similar voltage from the I/O card. Each interfaceable LED would need its own relay as there is no guarantee as to how many are 'ON' at any one time.

 

Another way is to control the input supply to the I/O card via the PWM so that I reduce the number of components (no need for relays) and simplify the exercise. I am thinking of the FDS type boards here, those which have dedicated switchable LED output pins. Is this possible?

 

I would be surprised if the AML lights were not dimmable in the real LJ45, they would need to be quite bright to be daylight readable, then at night it would be too much. Some aircraft have a Day/Night switch which dims warning lights/annunciators to a preset intensity. But I haven't seen or heard of that on the LJ45.

 

(Posted by Eric Tomlin on 05-21-12)

We are talking about dimming switch/indicators. The answer to Will's question lies in Channel 4 of the lighting system. Per the manual:

 

Pilot Left Crew Lights Panel:

The pilot’s L CREW LIGHTS panel is 28 VDC powered from the left essential bus and protected by a circuit breaker labeled “CKPT INSTRS L ESS PWR,” located within the LIGHTS group of circuit breakers on the left side circuit breaker panel. The four pilot LCU channels control:

 

• Channels 1 & 2–Pilot side main instrument panel, overlays, and instruments.

• Channel 3–Pilot’s circuit breaker panel.

• Channel 4–Left side bulbs that illuminate switch/indicators (S/I's).

 

Copilot Right Crew Lights Panel:

The copilot R CREW LIGHTS panel is 28 VDC powered from the right main bus and protected by a circuit breaker labeled “CKPT INSTRS R ESS PWR,” located within the LIGHTS group of circuit breakers on the copilot’s circuit breaker panel. The four copilot LCU channels control:

 

• Channels 1 & 2–Copilot side main instrument panel, glareshield overlays, instruments and pedestal overlays.

• Channel 3–Copilot circuit breaker panel.

• Channel 4–Right side bulbs that illuminate switch/indicators (S/I's).

 

With this said, I would like to offer up the following thoughts from someone that has already got his MIP installed and S/I's lighted up and working:

 

Going to the trouble of dimming your S/I LEDs is something that I would see as a labor of torture and not very useful in the sim environment. As you pointed out Will, in the daytime you need the S/I to be bright to confirm operation but unless someone here has created an ingenious day-time sunlight simulator that pours light into your flightdeck without washing out the visual system outside the sim, it will always be slightly dark in the confines of the flightdeck and the output of your interface card for the LEDs do not make them hard on the eyes at all at their current level. Then, beyond the point that it would probably be not very useful I cannot imagine the amount of extra wiring required to make this work mechanically. The better solution would be to have an interface card or logic that would reduce the current to dim them.

 

(Posted by Will Sasse on 05-21-12)

Thanks Eric, I had forgotten we operate in the 'twilight' zone of light intensity. Having no shell and only LCD's for externals I get a lot of daylight on my panel currently. I think a single intensity across all AML's may work and only have the panel backlights controllable.

 

I did ask Peter Cos regarding altering the input voltage to the LED power of his I/O cards, and his response was that they use a pulsed output to run the LEDs and as such it is not designed for that.

 

So, if anyone wants to try a series of independent relays I'd be happy to watch!