Quote from Ron Rollo on May 6, 2025, 12:06 pm

One of the most difficult and potentially expensive aspects of the Lear45 project is sourcing all the proper S/I switches, lenses and guards where needed.  If using the authentic Korry parts, your bill for just the switches could be up around $20,000.  Even if you try to use the Chromolux389 option, it will be nearly as expensive.

Fortunately, we determined the AML20 and the AML21 S/I switches are perfect to resolve this issue.  But even then, the cost for a full set can approach $2,000.  And the AMLs are getting harder to find and more expensive as time passes.  Here is a photo of several AML20/21 switches with the Project45 Lens and frame kits installed.

For the past few years several of us core members have recognized a need for an alternative solution to the AML switches for the next generation of Lear45 builders.  Unfortunately, there are no suitable solutions that address all aspects of the switch configurations while maintaining scale and the look found in the Lear45.

Key factors to consider are:

• Momentary or Latching
• Single Pole or Double Pole
• Single Legend or Dual Legend
• Tall Cap or Short Cap
• Guarded or non Guarded
• Color of LEDs and Legends
• Scale, Tactile feel and Mounting
• Cost and Availability

The solution?  Just design something that meets our needs!  I sent this list of factors over to our "design Team", (in other words myself) and came up with an incredibly simple solution that will be super cost effective.  Cost per switch will be less than $1.  (Not including the AML guards where needed)

From $20,000 to just about $1 per switch!

The only catch is the end user will have to make the switch bodies themselves with a CNC machine or a 3D printer.  The biggest cost for a complete set of switches will be time.  And after all, this is a hobby and it's all about spending time doing something you enjoy.

To date I have drawn up a complete plan for all configurations of the S/I switches.  See attached DXF drawing.

The key to making this work is the PCB plate at the base of the switch where everything mounts to it.  It's one universal design that will handle any configuration we need.  Single pole, double pole, single LED, dual LED, momentary, latching and of course annunciation where needed.

One "universal" design takes care of all configurations we will need.  See photo of the prototypes!

Another big part of the solution is the Latching and Momentary switches.  These can be found on eBay and Amazon for as little as 10 cents each when purchased in larger quantities!  I have purchased several sample batches and for the most part, they are all fine.

I did get one sample batch of the momentary switches where the tactile feel was not as strong as the other samples.  One other interesting thing I discovered is that a Latching switch could be modified into a Momentary switch by removing a small piece of plastic internally.  The tactile feel still remains as strong in both cases.  In other words, what we want is if we push the button, we feel a clicking no matter if it's latching or momentary.  We get this!

Now with all this said, the tactile feel is not as strong as what we get with the AML20/21 solution.  And the travel of the switch is not as far as the AML20/21 solution.  That is the only compromise to this replica solution.

None of us core guys need this S/I switch replica solution.  This is being developed for the future builders to give them an alternative option besides the AMLs.  I am in the process of building up seven S/I switch replicas that represent all configurations found in the Lear45.  In order to showcase these switches, I am also building up a small S/I Example Panel.

This panel will have a couple additional trigger switches that will activate things like the WARN and CAUT LEDs, a LTS TEST, Gear toggle and even a Rest Button.  The front panel will also be backlit and to show it all off, just plug it into a  nearby USB socket.

I have already put together a basic Arduino sketch that turns LEDs on and off depending on what you push.  (Some basic logic tested in this example below)

All this to showcase these S/I Replica!  Most likely, these seven S/I replicas will be the only ones I build up fully to prove that they are a viable option to the AML solution.

PCB development for me has become second nature and fun!  I went ahead and developed a S/I Replica Module.

Here I have everything plugged up and tested.

The hard part is done!  The time consuming part is still to come!

This is what I call a "back burner" project which means there is no immediate rush to complete this.  For most of us it's a curiosity thing.  Can we develop a S/I replica solution or not?  This is going to be my best effort at solving this problem.  I think it will work!  Feel free to take any of these ideas to apply to your own S/I replica solution.

Another update soon!