A question about potentiometer of a TQ

Hello, I'm starting to build a 737ng throttle quadrant but I have a problem with the potentiometer of the throttle's levers. I built an usb I\O card with 5 axes and 25 buttons which works perfectly. The potentiometers (10K) that I use has a rotation of 300 degrees while the throttle levers of the 737 has a rotation of 60 degrees. I did a first test with a simple piece of wood with two gears (one small to potentiometer / one large to lever) but I can not use full travel of the potentiometer.
Thus, when the lever is at its maximum rotation, the engine in flight simulator stops at 50%... how can I fix this?

Hi Iron737,

I used a set of gears that gave me approximately 270 degrees of travel. I didn't use the full travel of the pot. I used an 18 tooth gear on the pot and a 58 tooth gear on the lever. After I calibrated in FSUIPC4, I had just a little bit on each end for a small dead zone. I also installed a sub micro switch at the idle end of each throttle to ensure idle has been reached to allow the reversers to function. You can check my website for pictures on my throttle levers. I'm still in the process of building my own 737NGX throttle quadrant.

Your lever stopping at 50% though sounds like it could be a calibration issue, but dont quote me on that. In my mind, I think one should be able to calibrate idle to full throttle on even half the distance travel of the pot if so desired, but doing so wouldn't give you the realistic travel of a real 737 throttle lever.

Hope this helps somewhat, and probably others may answer with better information also.

Ed

www.737ngxca.com

Ok many thanks birdyguy!

I have not tried using FSUIPC but I just tried doing the normal calibration of the axes from windows and then I assigned the axes on the control options of flight simulator.
So, with FSUIPC I can use, for example, only 50% of the pot and get the full throttle? This applies to all axes?

Hi Iron737,

FSUIP4 is a great bit of software. Worth every penny. You will need the registered version in order to use it for calibrating axes and setting up buttons and switches and such. I found it an invaluable tool when building my throttle quadrant. I used it for my flaps, two throttle levers and my speed brake and many many buttons and switches.

It's been my experience that you do not have to use the full range of the Pot. There is an example in the manual that allows you to use part of an axes for throttle and the remainder for reverse thrust. I would think calibrating in Windows and FS would allow you the same options, (minus the reverse thrust) but not sure as I only use FSUIPC4 for my throttle axes calibrations.

Myself, I set a dead zone at each end of the pot to allow for variance's in the pot readings, this 'dead zone' allows you to reach the minimums and maximums each time. I hooked up my pot to my levers, fired up FS and then matched my lever travel with that in my NGX, Then I set my stops according to that. After setting up the first lever I did the same with the second , and then used another neat tool in FSUIPC4 which allows you to sync the two throttles levers to each other. After syncing them, they then travel together in the same plane as each other if advancing both at the same time.

Hope this sheds more light on things for you,

Ed

Ok Ed, thank you for all the information, you have been very helpful!
I registered my copy of FSUIPC and I did a lot of calibration test...I have to say that it works perfectly!
Now I begin to procure all the materials needed to build my TQ!
Thanks again and congratulations for your TQ ;)

But now I have a doubt about the construction of the trim wheel. How could I do to recognize clockwise and counterclockwise movement of the wheel? I predict two switches? I have seen many projects where there is only one pulse switch but I don't understand how you can recognize the movement clockwise and counterclockwise...

Hi Iron737,
More than welcome and glad to be of help. You will find FSUIPC a great tool to use. Thank you for congrats on throttle. I'm getting closer to the end of it, trim wheels. cover with aluminium, paint and build a pedestal stand for it.

I am currently working on my trim wheels at this time. To make it simple and easy I am going to try using a pulse switch that acts as 2 different buttons. You can see the schematic of the switch on Ian's site http://www.737ng.co.uk/technical.htm , scroll down until you see the little pulse switch. I ordered two of those from Mouser and I believe I have them working reasonably well. I've set them up under 'Buttons and Switches' Tab in FSUIPC4 at the moment but I may still play around with them in other tabs in FSUIPC4 to see the different results, if any. At the moment, the switch when turned one way will move the trim wheel up, when turned the opposite way moves it down.

I plan on setting the trim wheels up similar to my other axes, a large gear on the wheel shaft, and a small gear on the pulse switch. One revolution of the big gear should turn the little gear 4 times which is about half a graduation at the moment. So two turns on the big gear will equal one graduation mark on the trim scale, I think :-) Remains to be seen as I haven't installed gears and wheel yet , just testing with the switch and Bodnar card and FSX.


All the best,

Ed

I haven't yet figured out a way to have a guide point to the scale to show where the trim is set at, but if it's too complicated I will leave that part out for now.

Wow congratulations again! You're doing a great job and you're giving many interesting details for me. The idea of ​​using a pulse switch is perfect and should be easy to implement... I hadn't thought of that.
About the graduated scale of the trim, I think of a set of gears properly calculated...we need a lot of work and testing.

Are you using the card of Leo Bodnar?
I made ​​my own card: I designed it to simulate the push of a button made ​​with a common on-off rocker switch when the switch changes his state (from on to off or vice versa). Bodnar's card works in this way? You can connect both push button and rocker switch? It

I've a problem with my card because when I press a normal push button, I've got two different "pulse" in a fraction of a second: one when the button is on (press) and one when the button is off (release)...so it's like a double click :roll:
For this reason I've a problem with reverse: when I insert the reverse, I have no problem but when I remove the reverse, the lever releases the contact of the switch and my board interprets this as another pressure so the reverse can not be removed. If I set a throttle idle for "control sent when button released" in FSUIPC, the reverse doesn't insert...so I should use these switches as normal push button: when the switch is pressed (the reverse lever pulled) I have to simulate a continuous pressure of the button while when I release the lever, the throttle must returns to idle.

I wired the switches like Rudy's project: http://www.737ngproject.be/Doc/Cablage/sm_Reverse.jpg
Have you had similar problems with the reverse?
This is my FSUIPC settings for the reverse: http://uptiki.altervista.org/viewer....qmqyj86cxm.jpg

Hi Iron737,

Thanks once again for your kind words. The detentes on the pulse switches are a little stiff, so hope the plastic gears will stand up to it, but in testing without gears attached they seem to do what I'm looking for. The graduated scale of trim indicator will definitely give cause to some serious thinking.

Yes , I am using the Bodnar Card. BU0836X for all my throttle axes and buttons. I am not that good with electronics to make my own devices. Would love to learn that skill though. The Bodnar card sees 32 button/switches. FSUIPC4 will see that as 64 actions. One for a button or switch on, and another action for button or switch off. I believe I've read that there are even more actions that can be configured, may have been on Ian's sight, I forget at the moment. I would think a rocker switch could easily be connected to the Bodnar card. I have 4 push button, 2 micro and 6 sub-micro switches on my throttle.


I'm not sure about the double press action on your card. The Bodnar card in conjunction with FSUIPC4 allows you set an action when the button is pushed, or when it is released, or two actions, one for a push and one for a release. It's FSUIPC4 that allows you to configure these actions to the best of my knowledge. You can also set the buttons to repeat if necessary.

My reverse system is also wired the same as on Rudy's site. I have a sub micro switch on the idle end of each throttle. When I idle back, the throttle lever contacts the idle switch, which closes the connection to the reversers as well as ensures a definite idle position. I have a micro switch in the top end of my throttle levers which activates the reverse thrust. My NGX will not allow a reverse thrust action unless the idle switch completes it circuits.

I think you should be able to solve your reverse problem with FSUIPC4. This software should work just the same with your card as with the Bodnar card...I think:-) Be sure that you have no conflicting assignments in FS when you set things up in FSUIPC4. I dont have my throttle attached to my pc at this time so can't really see what I had set in FSUIPC4 for this. From memory I believe I used the F2 key press. So, in a nutshell, my throttle lever would contact the idle switch, this would set my idle and close the circuit to my reverser switch. The reverser switch on contact would act as an F2 key press which would repeat. On release of thrust lever, the switch would end the F2 key press and reverse thrust would end. The next time I have my throttle attached I'll double check my settings and get back to you.

Hope this sheds a little more light on things. I'm sure you will get the reversers working properly, just a matter of tinkering around with FSUIPC. :-)