Introduction

"Legos??"  "Are you kidding?"  Legos are actually flexible, durable (if built right), and quick to build with.  And if your like many parents, you probably have possibly $100s of the stuff just laying around.  Whether you build with Legos or other raw materials, this write up will show you how to build a custom throttle quadrant.  This project will take about 3 days for parts to arrive and about 4 hours to build.

(If imitation is the sincerest form of flattery, I own my initial inspiration and some of the documentation from  Rob Barndregt and is write-up "How To: Make Your Own 4-Engine Throttles for FS2002" www.flightsim.com 's library as RCBth-10.zip).  

Motivation for a Throttle Quadrant/Pedestal

As a private pilot, I've always valued FS2002 as a real tool to help keep many skills current.  And for fun, I find the flight simulator environment is the only way I'll fly exotic and expensive big iron.  One problem I never liked about my home cockpit was that I was hampered by how my left and right hand were doing tasks vs. the real cockpit.  I was holding the stick right-handed and running most other function left-handed which opposite to my Cessna cockpit.  My goal then was to rebuild my home cockpit so my tasks were at least "hand correct".  And thus the custom quadrant.

What is needed and how to buy:

I'm including links to all the parts require for this project.  (This delayed my first release because radioshack.com decided to get out of the parts business.)  For me this project was about $30 total given the near unlimited supply of Legos I had at home.  If you don't have the Technics Legos (the one with the good gears) then order this for $17.  If you are just introducing yourself to Legos, then another $20 in starter set is needed.  The pictures are using my bucket of Legos not from this kit, I have pictures of the same setup using the start kits at the end.  If there is a specific part of two you just can't live without, consider purchasing specific Lego parts from here. 

I do not recommend trying to purchase electronic stuff at a local store (unless you have killer electronic stores that I just don't have access to in Sacramento).  I've included links for ordering in the US.  If you live outside North America, the links include the part numbers and manufactures and I'd recommend finding a good general purpose electronics supply shop.  

For the electronics, the readily available analog joystick to USB converter provides both a lost cost and low risk to blowing up your computer solution for connecting to your computer.  The Radio Shack 26-164 ($16.99) USB gameport adapter allows 4 analog ports and 4 buttons.  It connects using a standard 15 pin (DB-15) male connector (here and here) and I used 6 ft of 10 conductor shielded wire. Mini 100KOhm pot provide 210° rotation and mini buttons provide easy solution for the flaps and other buttons you might consider.

Marrying the electronics with the Legos is as simple as wire wrap (here and here and here) (better than soldering in my opinion).  Mounting the potentiometers is done using inexpensive and moldable epoxy putty.  Connecting your new throttle quadrant to FS2002 is best done using FSUPIC.

Assembly

The pictures will say most of what needs to be said about gears and what not.  Part of the fun is experimenting with various designs getting the right look and feel vs. the real thing.  Don't just rebuild what I did as experimenting is most of the fun with Legos.  

Sadly, Lego doesn't make 100K ohm potentiometers so they will need to build your own "Lego pots".  Using epoxy putty, just cut the amount you want off the "tootsie roll" (about 3/4" per pot) and kneed it between your fingers.  You have about 5 minutes before the putty turns into a very hard clay and about 1 hour before it turns into a rock.  I pre-built a jig to make all 4 pots at the same time and then built one at a time.  Keeping your fingers wet with water keeps your fingers and everything else from being a mess.  After 3-4 minutes you can take small blade and trim the edges for style points.

After they are built, they will work in any Lego configuration

The flaps are built with a simple push up/push down with a micro push button switch at each end.  The buttons are held in place with a small Lego 1x2 piece with a spot of super glue:

To make the flaps switch more stable and more rugged, I added a set of support Legos which hides one of the switches..

USB or not USB

The method of converting a variable resistance to a number that FS2002 can use is done by measuring the time it takes to charge a capacitor through the resistance (don't worry if you didn't understand any of this paragraph, this is just ranting of a computer architect).  Although most computer have an available analog joystick port at its disposal, I don't recommend using it.  By using the PC's joystick port, you are asking the main CPU running a multi-tasking and multi-treading operating system to measure time without interrupts. This both consumes useless cycles and has limited accuracy because of the other jobs the CPU is doing.  The low cost USB game port adapter uses a small dedicated processor (I have details if interested) for this time measuring task and provides a simple digital value to the main computer.  I strongly recommend going USB if you have an available port and an extra $17.

Wiring it all up

I'm going to borrow Rob's diagram from his excellent first article.  My only modification was to use 10 lead cable to allow routing the 4th button.

In my implementation I ran 6' of 10 conductor shielded wire and placed the USB converter close to the USB hub.  If I were to do it again, I'd place the USB converter on the throttle quadrant and use a USB extension cable.  

Somehow the "permanency" of soldering wire seemed counter to using Legos allowing freedom of easy changes and updates.  Thus starting from the other end of the cable and for the remainder of the electronics I used wire-wrapping.  If you've never worked with wire-wrap before, it provides both reliability and easy rework.  I used an 32 pin upside down DIP socket as a wire wrap mounting post area and trimmed off every other pin for more spacing.

Since the wire wrap tool is made for 30 gauge wire and the 10 conductor is 24 gauge, I trimmed about 1/2 the strands and didn't wrap any of the insulation as is typically done.

Finishing 

Although I chose to keep my wiring exposed because I continue to tinker with the design, there is some risk having exposed power and signal wires.  Although not a shock risk, if the power wires are shorted I really doubt the USB converter fuses them and there is a risk that it might make your PC supply unhappy and/or a fire hazard.  And although (most) modern chips are quite good at protecting themselves against damage from electrostatic discharge (ESD) there is a risk that a good "zap" from your fingers might damage the USB converter, joystick port, or worse.  Thus I plan on, and recommend you also, cover the exposed wires in either Legos or some other enclosure when your happy with your design.

Connecting to Windows and FS2002

Rob Barndregt's article does a good job describing the task of connecting your joystick to windows and fs2002 through FSPUIC and doesn't need to be repeated here.  See Rob Barndregt write-up "How To: Make Your Own 4-Engine Throttles for FS2002" www.flightsim.com 's library as RCBth-10.zip).  

So what if you don't have a zillion Legos around the house?

Below is a throttle quadrant I built using the two starter sets I recommended.  I'd consider doing a better wheel for trim and add some lead weights to hold it down, otherwise, I think it looks great.  

Parts Lists

Final Words

Please accept the standard disclaimers about the fact that I make no warrantee about whether this will work for you and/or not put yourself and/or your computer at risk.  Your on your own!  However by using a USB gameport adapter, most risk of hurting your machine is removed.

Please feel free to email me with ideas, suggestions, questions, etc.  I'd love to see pictures of various implementations and I'll include them in a future revision.  

---Steve,  Northern California

E-mail: StevenWells@RFADesign.com

Revised: 01/11/2003

May 3 2002 - First rev
June 1 2002 - Revised list of suppliers