Building my four engine throttle quadrant (repost)

[JBaymore]

This is a starting point for moving prior postings from the "Homebrew Cockpits Survey" thread. Messages will likely get out of the original sequence.

[JBaymore]

If this thread were a separate forum section I'd probably use this message header:

Preliminary news on 4 engine throttle interface

With the interfacing of a 4 engine throttle control quadrant on my mind....and the thought from others that a second USB joystick could be installed under Win XP in FS2004..... I headed off to Walmart today to see what they had in a cheap 4 axis joystick.  Was expecting to be in the $50 range , plus or minus.  Quite a bit of money...... but what I thought was going to be necessary.

Then Will's comment about his using a joypad popped into my brain as I was looking at the offering there.

They had a cheap ($17) AxisPad FX usb dual joystick gamepad.  It had side by side small analog joysticks..... and a usb interface.  At that price I thought "What the heck" and I bought it.  Figured that if I was just looking for the circuit interface and the software drivers...... didn't need the rest of the heavy duty "joystick" parts that I'd have to pay for that I was not going to really use.  I'd be adding external switches and potentiometers anyway.

Brought it home and hooked it up.  Snap of an install in XP.  

Went into the FS2004 sim.  Now in the "Settings" part there are both the Logitech FF joystick and the Axis gamepad FX showing up there.  So far so good.  I went to "Assignments" and then selected the gamepad in the dropdown list.  Then I mapped one of the joysticks on the gamepad to engine one throttle.  Mapped the other one to engine four throttle.

Then went into "create a flight" and went to the default flight.  Poped up the virtual throttle quadrant.  I EXPECTED the main throttle on the Logitech stick not to work anymore.  But lo and behold..... when I ran it up..... all four engines spooled up.  Great.  At least it didn't screw things up  ;).

Holding my breath.... I pushed one of the gamepad joysticks forward...... then there on the screen ONLY engine one started spooling up.

So BINGO!!!!!!!!!!!!!  This looks like it will form the basis for a multi engine throttle quadrant interface.  Still a LOT to do.  I have no schematics..... and the inexpensive device is made in China so I probably can't get them.  So I still have to rip the thing apart and see if I can reattach four linear potentiometers to the thing and still get it to work.

The unit ALSO has 8 momentary buttions available and an 8 way hat switch.  All of which can be remapped for function in the sim.  So this would give you 16 more switches you can control stuff with.

And it has two vibreation feedback things that I have no idea how to interface  ;D.

This is a real WOW in moving this project forward inexpensively, I think.

I'll keep you posted.

best,

....................john

[JBaymore]

Will,

Ah...... yes.... you are correct........ but I will now unsolder the two mini joystick potentiometers from the printed circuit board and replace them with four remotely mounted linear slide potentiometers that will themselves be actuated by four lever arms (making the throttle quadrant).  Each of those pots will then be a single engine throttle.

After all ....... this whole cockpit construction thing is about "tinkering".      ;D

On the joystick....... let's say that one axis of the pot is forward and back.  If it is a 100k ohm pot....... the center position is at 50k ohms.  So the signal sets the coordinate "position" of that stick to "center" in the sim when the resistance value is at 50k ohms.  When you move the stick full back..... the pot changes resistance heading toward 0 ohms.  So the "position" moves to the bottom.  So when you add a new pot ......... the zero ohm position relates to "full down".... and therefore idle throttle.  And the full "up" position now relates to 100k ohms and full throttle.

I may find that I have to add what are called "trim pots" along with the main linear control ones..... to fine tune the "range" of the throttle.  Those will be a "one time set" type of thing.  But that is a minor and simple addition.

The first trick here is to carefully unsolder the pots.... and then figure out which traces on the circuit board are the ones for each control axis.  Then I just take the pot and connect it to a multimeter and run it from full down to full up and see what resistance it is.  Once I know that..... I can get the linear slider pots to replace them with.

I will also add a "terminal strip" to all the switch contact points so that adding wiring for external switches will be far easier than trying to solder directly onto the circuit board.  Not sure if I'll use ribbon cable or not.

I will document all this construction as best I can and post all the work here on SimV.  I may also add something to my (non-flightsim) website.  I have been taking digital shots of the "destruction"  ;) of the gamepad.  Hopefully Pete will decide that a separate Forum dedicated to this kind of stuff is appropriate and there will be a "files" section created to put this kind of stuff into in something like PDF format.

The next thing I want to know here is if I get ANOTHER "cheapo" Axispad FX and install it in Win XP...... if it will get recognized as a third controller........ or because it is the same unit...... if it will get "confused" with the existing one.... and will then be difficult to "map" buttons and axis assignments in the sim.

Then there is stacking a CH products usb yoke on top of all those  ;).  Gotta get a (powered) usb port box too to support all of these usb addons.  


best,

.................john

[JBaymore]

First Test of Throttle Quadrant Construction

Spent some time this evening taking one of the numerous designs I've been playing with off of "paper" in the CAD program and trying to turn it into a real 3-D rendition of some sort  ;).

Here is an image of the VERY unfinished four engine throttle quadrant idea for my developing simulated cockpit design.  

It is set in width to coordinate with the width of the GoFlight panel mount instruments (7 1/4").......... so that it will align well with them if it is mounted in a "rack" that also holds some of them.  It is 9" long.  The flat section just to the rear of the rounded part will hold a few switches that will be mapped to engine control functions.

This is still VERY early in the design revision stage..... some changes will still be made to even the basics.  But this now gives me a "feel" for the idea.

[JBaymore]

1st Revision of Throttle Quadrant Layout

In learning from looking at the FS2004 "Axis Assignments" that both the flaps and the spoilers can have infinite potentiometer control mapping......... I decided to add the spoiler control to my throttle quadrant.  So that put another angled lever arm to the left of the four throttle levers..... bringing the total levers to six.

I also did not like the way the tension on the resistance to movement for all the levers worked in the older setup.  Too difficult and fussy to set each control individually.  So I changed to using some nylon bushings and then will compress the whole assembly from the sides using 1/2" nuts on the 1/2" threaded rod "shaft".  No individual lever control of tension.... but much simpler.

The "mount" to hold the shaft is simply a piece of metal from a joist hanger bent into shape and drilled to accept the 1/2" threaded rod "shaft" at 1" height above the bottom of the box.  The lever arms themselves are cut from stock shelf brackets that fit into wall mounted strips with slots.  Two cuts for length and drill two holes and they were done  ;).

The annotations on the drawing should help you figure out what the various parts are a bit.




One thing that I have to decide here soon is if I will actually "waste" an available channel of "joystick axis" (potentiometer control) from one of the AxispadFX gamepads on the spoilers.  I can also set the spoiler arm lever to just hit a microswitch at the "Arm" point, and another at the "Deploy" point...... and have that just emulate the keyboard presses.  Any thoughts on the subject of having infinitely variable spoilers versus just a "one press = full deploy" type?


best,

..............john

[Daz]

looking good so far even in the early stage of construction. keep us informed made for an interesting read this post

[JBaymore]

Daz,

Thanks.  I will be updating this info when I take the next steps.  Wish I had more time to devote to the project...... but life often gets in the way of "virtual life"  ;).

There are so many aspects to the construction of a homebuilt cockpit flightdeck that it can be very time intensive.  At least I can tackle different "types" of things...... that can fit into differnt types of available time.

best,

................john

[jahanzeb]

hi guys.. im building a 737 throttle quadrant.. from scratch.. i wanted to know if i can use 10k pots for throttles, as i cant get ahold of 100 and 200 k pots.. it will just make the throttles more responsive right?

secondly.. my windows dosent detect the "joystick" that im making.. here's what ive done.. ive connected a 15 pin male DA 15 with a female (gameport) and soldered wires from the female to a male usb plug.. the male DA15 is connected to one pot only.. further, ive connected a another wire, which will later be attached to a trigger (button)
i've tried to detect this setup in both windows 7 64 bit.. and xp sp2.
in xp, where u add game controllers, i added custom joystick with 2 axis and 2 buttoms... but it says usb device not recognized.. any suggestions?

the pot tht i connected was with the help of this site
http://www.simpits.org/articles/throttl ... tquad.html

i dont remember the other site which i used to connect to the 15 female with a usb plug.. i saved the jpg image..

any suggestion wud do

[machineman9]

Damn, son, didn't you check the timestamp? 

[jahanzeb]

haha actually i didnt.. was too engrossed in reading the material.. this post has been dead for 7 years lol.. anyway i figured it out