Exporting and driving a caution panel for the huey

[Studsmcgee]

So I’ve stumbled into making more panels for my Huey cockpit. I’ve acquired an original caution light panel and I’m hoping to incorporate it into the build and make it work with dcs. 
 

First off I’ve done lots of switch panel builds. But I’ve never messed with getting data OUT of dcs to drive physical devices. 
 

What do I need to export the caution light data? Also any advice on what kind of circuit I’d need to power leds or lights? I’ve head about using an led matrix and an arduino but I’m clueless at how that works. 
 

I’m not above disassembling the panel (I think I’ll have to as it was designed for 28volt DC power). 
 

I’d appreciate any general or specific advise on how to go about this. Thanks! 

[No1sonuk]

If you can supply 24V, that should also work.

Do you know how it's wired?

If it's individual lamps, some sort of MOSFET driver would work. 

[Studsmcgee]

I did open it up. And it seems like there’s individual lamps. Probably two bulbs per cell. There’s a schematic on the back but I’m not sure exactly what it’s telling me. I also haven’t found the connector that would work with in. I can post a picture later.  

What kind of mosfet would I use? And can that connect to dcs or would I need an arduino in between or something. ?

 

Edited September 4, 2022 by Studsmcgee

[No1sonuk]

Looks like connecting any of the top three wires to ground will turn on the corresponding light when 28V is applied as shown at the bottom.

Any "N-channel" MOSFET meant for motors, etc. would do that, and you'd need an Arduino to drive the appropriate MOSFET

As for the connector: Unless you can find one, you'll need to source some pins and 3D print a housing, or disassemble it and rebuild the inside.

[Studsmcgee]

48 minutes ago, No1sonuk said:

Looks like connecting any of the top three wires to ground will turn on the corresponding light when 28V is applied as shown at the bottom.

Any "N-channel" MOSFET meant for motors, etc. would do that, and you'd need an Arduino to drive the appropriate MOSFET

As for the connector: Unless you can find one, you'll need to source some pins and 3D print a housing, or disassemble it and rebuild the inside.

Man Are you an electrical engineer? How’d you figure that out? I’m impressed haha. 
 

I’ll have to play with it more soon. I’m looking for a connector but no luck. 
 

In this case would I need a mosfet channel for each light? And then program the arduino to switch the mosfet to ground when the caution light in game is on? (I’m a novice when it comes to circuits like this). 
 

 

[No1sonuk]

Yes, Electronics engineer. 

I only had a quick look, as I'm away from home until Wednesday, and the diagram has a weird layout.  e.g. it looks like the bulbs are in parallel (as they should be for redundancy), but theyre drawn in an odd way. That may so so the diagram would fit the shape tgey have to work with. There are transistors in there, and it would need a proper look (and probably redraw of the diagram) to figure out what's going on. It's also a bit out of focus.

Those transistors mean it may not be as simple as changing the bulbs.

They also mean a MOSFET might be advisable rather than required. I just cant tell on my phone.

Most of the motor drive MOSFET modules are rigged to ground the "output" when they are turned on.

It's "simply" a matter of using the "LED" code lines of DCS-BIOS to turn on the appropriate output that connects to the MOSFET input.

Edited September 5, 2022 by No1sonuk

[Studsmcgee]

5 hours ago, No1sonuk said:

Yes, Electronics engineer. 

I only had a quick look, as I'm away from home until Wednesday, and the diagram has a weird layout.  e.g. it looks like the bulbs are in parallel (as they should be for redundancy), but theyre drawn in an odd way. That may so so the diagram would fit the shape tgey have to work with. There are transistors in there, and it would need a proper look (and probably redraw of the diagram) to figure out what's going on. It's also a bit out of focus.

Those transistors mean it may not be as simple as changing the bulbs.

They also mean a MOSFET might be advisable rather than required. I just cant tell on my phone.

Most of the motor drive MOSFET modules are rigged to ground the "output" when they are turned on.

It's "simply" a matter of using the "LED" code lines of DCS-BIOS to turn on the appropriate output that connects to the MOSFET input.

 

Ok. I’ll get a better picture of the diagram and the connector soon. 
 

If you get a chance could you possibly have a name or a link of what kind of mosfet I’d need? I Google searched a bit and there’s a lot of options and I want to make sure I have the correct one before I go and buy 20 of them or something. 
 

Thanks again for the help. 

[Studsmcgee]

Here’s a better picture. 
 

I’m still at a loss as to what connector is on there. Something with 26 pins. 
 

[No1sonuk]

Looks like some of the writing is a part number.

What are the lights indicating?

[Studsmcgee]

5 hours ago, No1sonuk said:

Looks like some of the writing is a part number.

What are the lights indicating?

Well clearly I'm blind. the part number is a Continental 26-20P. I found one on ebay. 

 

And if you mean the purpose of the lights there are 20 indicators for caution/warning conditions. Low oil pressure, trans temp, things like that. 

 

Do you think a 24volt power supply would run it assuming I can figure the wiring out? Those seem easier to find than a 28 volt power supply. 

[No1sonuk]

The mating half is possibly 26-20S.

20 indicators puzzles me. Only 4 circuits are shown, and they're all different. 

[EvilBert VR]

Hey guys,
I guess this will help you ;-)
Cheers

[Studsmcgee]

3 hours ago, EvilBert VR said:

Hey guys,
I guess this will help you
Cheers

 

Thanks EvilBert. That makes a little more sense to me. 

I know you have quite the huey cockpit build. Were you able to get the caution panel working with DCS? If so I'm curious as to what hardware you used.

[Studsmcgee]

UPDATE: I've acquired the proper connector and I've confirmed No1sonuk is correct. Grounding the pin associated with the caution light while applying 28 (in my case 24) volts makes the light illuminate. 

Now it's just a question of making the DCS BIOS code work and then finding an arduino and a mosfet board with enough outputs to make all the lights work. 

 

[No1sonuk]

How about 3 of these?
https://www.switchelectronics.co.uk/24v-8-channel-relay-board-module

Relays might be better because it looks like some of those inputs need to go to + (2,3, and 10).
Plus, you can invert them by changing NO to NC.

Edited September 18, 2022 by No1sonuk

[Studsmcgee]

41 minutes ago, No1sonuk said:

How about 3 of these?
https://www.switchelectronics.co.uk/24v-8-channel-relay-board-module

Relays might be better because it looks like some of those inputs need to go to + (2,3, and 10).
Plus, you can invert them by changing NO to NC.

 

That looks like exactly what I'd need. 

Can you expand a little more on what you mean by those inputs need to go to + ? Do you mean positive? I apologize my electronic circuit diagram skills are mostly non existent.

I tried setting up a test with a mosfet I have but I don't think I got the wiring right. Any chance you might be able to explain what needs to be connected to what?

Again I really appreciate the help.  

[No1sonuk]

When you look at the diagram on the back, most of the switch symbols have the ground symbol on the left.  The ones for 2,3, and 10 have "+" next to them.
I assume that means those particular ones need to be switched to positive power rather than gnd.
That's what makes MOSFET switching a bit harder.  MOSFETs only go one way, so you need them to be the right way round. 
e.g. For an N-channel MOSFET, the + of the load needs to be at the +supply, and the -ve side of the load needs to be at the "Drain" pin of the MOSFET.
Then the "Source" pin of the MOSFET goes to supply gnd.
A positive V on the "Gate" pin will turn on the MOSFET and hence the load.  This is "low side switching", and is the most commonly used for "one-way" loads.

"High side switching" is done with P-channel MOSFETs connected on the supply side of the load.
A good explanation is here:
https://www.baldengineer.com/low-side-vs-high-side-transistor-switch.html

Relay contacts are mechanical switches, so polarity doesn't matter, and frankly is what I'd use for that application.  It's far simpler (and cheaper) than messing about with MOSFETs, and is likely how the real one works to some degree.
Also, because the relay switches are double-throw, if the light response is the wrong way round, you can change the physical wiring easily, rather than messing about in the code.
The opto-isolated relay boards are driven like LEDs, because that's exactly what's in the isolator.  They may already have the load resistors so all you need to do is feed it a digital signal straight from the Arduino.

And remembering that the Arduino analogue pins can usually be used as digital outputs, you'd have enough outputs to drive the 20 relays for that display from a single Nano or Uno, etc.

Edited September 19, 2022 by No1sonuk

[Studsmcgee]

Ok I see what you meant about polarity with lights 2,3,10. 
 

The relay board looks like it would work. If I understand correctly all it needs is dc input, then a 1 wire signal from the arduino into the board. And then connect the panel lights to the relay side? Does that sound right? 
 

Additionally, I only have 1 24v power supply. It has plenty of amps to drive everything but how can I run power to all three boards from one plug? 
 

In the same vein, the caution panel has one input for power. But each relay seems to need an input and output? Maybe I’m not understanding correctly but how would this all work together? Would I only need 1 wire from the caution panel into each relay? 

Here’s a quick drawing of what I was thinking. Not sure if it’s even close but I’m trying to figure out how to power all the relays but have only 1 power supply and 1 DC input to the caution panel. 
 

Still haven’t figured how to expand this to include three boards. 

Edited September 19, 2022 by Studsmcgee

[No1sonuk]

The 24V power is easy - create a couple of bus bars and tap off for each module that requires it.
You can buy, or make, terminal block bus bars quite easily.
 

4 hours ago, Studsmcgee said:

The relay board looks like it would work. If I understand correctly all it needs is dc input, then a 1 wire signal from the arduino into the board. And then connect the panel lights to the relay side? Does that sound right? 

Correct.
1 wire per light signal and common ground - you're sending a logic signal.  It needs a ground reference.
Some relay boards have a completely separate relay power input.  How it works depends on what you can get where you are.

Your relay contact connection is "wrong".  It will work, but might be confusing down the line.
When the relay is off, COM is connected to NC (Normally Closed).  When the relay is on, COM is connected to NO (Normally Open).
Connect the light panel signal line to the NO on the relay and the common GND (or +ve for 2,3 and 10) to the COM connection.
Putting the signal "output" on NO or NC means it's a bit easier to keep track of if you have to move it to invert the action.

 

[Studsmcgee]

On 9/19/2022 at 2:15 PM, No1sonuk said:

The 24V power is easy - create a couple of bus bars and tap off for each module that requires it.
You can buy, or make, terminal block bus bars quite easily.
 

Correct.
1 wire per light signal and common ground - you're sending a logic signal.  It needs a ground reference.
Some relay boards have a completely separate relay power input.  How it works depends on what you can get where you are.

Your relay contact connection is "wrong".  It will work, but might be confusing down the line.
When the relay is off, COM is connected to NC (Normally Closed).  When the relay is on, COM is connected to NO (Normally Open).
Connect the light panel signal line to the NO on the relay and the common GND (or +ve for 2,3 and 10) to the COM connection.
Putting the signal "output" on NO or NC means it's a bit easier to keep track of if you have to move it to invert the action.

 

 

Ok so I got a relay board in. This picture is how I connected it to test. The question mark is what I can’t figure out. I tried every way I could think of but I can’t get the light to trigger. 

The arduino triggers the relay properly and I can hear the relay clicking whenever the correct light in dcs illuminates. 

To be clear the physical caution light illuminates when I have DC+ connected to the input and dc- connected to the pin that is specific to the light. I don’t know if DC- is the same as a ground connection? Maybe you can elaborate on that?  
 

MAJOR EDIT:

I got the whole thing to work! I sat back and realized the relay is just a switch. I wired it up splitting the DC+ into the relay board inputs as well as direct into the caution panel, and sending the DC- into the relay board as well. Then I wired the caution panel pin for the specific light to the Normally open side of the relay, then the COM side back to the DC- of the power supply. I'll upload a diagram shortly if anyone is curious. 

 

 

 

 

 

 

Edited September 28, 2022 by Studsmcgee

[No1sonuk]

6 hours ago, Studsmcgee said:

MAJOR EDIT:

I got the whole thing to work! I sat back and realized the relay is just a switch. I wired it up splitting the DC+ into the relay board inputs as well as direct into the caution panel, and sending the DC- into the relay board as well. Then I wired the caution panel pin for the specific light to the Normally open side of the relay, then the COM side back to the DC- of the power supply. I'll upload a diagram shortly if anyone is curious. 

This is exactly it.
Though from the diagram on the unit, some might need to go to the Normally closed side to work the right way round.

DC- in this case is the same as ground.  I don't like saying that is always the case because you might have an actual negative supply for some applications.

[Studsmcgee]

14 hours ago, No1sonuk said:

This is exactly it.
Though from the diagram on the unit, some might need to go to the Normally closed side to work the right way round.

DC- in this case is the same as ground.  I don't like saying that is always the case because you might have an actual negative supply for some applications.

Once I realized the board doesn’t pass the power through to the relay it finally clicked for me. 
 

I still need to solder all the wires to the connector to test each light and then find a way to get at least the test and reset switches working. I’m not too worried about the bright dim switch. I don’t think I’ve ever used it in game. 
 

Also No1sonuk I really appreciate the help! Thanks again.