Cougar Throttle Hall Effect Potentiometer - Cubpilot Reincarnated!
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Chaps,
I had wanted to do the cubpilot Hall Effect Sensor mod for my throttle for a long time. Mainly for in-flight refuelling. I had held off a long time until BMS 4.33 was released. I tried a couple of years ago to contact the chap who made the kist but sadly he seems to be no more and neither is his website.
Not to be deterred, I made my own. The total cost is about £36 (that’s British Pounds Sterling) but could be cheaper if buying parts off eBay perhaps. The parts are readily available from Farnell and your local DIY centre and radio control modeller shop - or eBay. I’ll do a full parts list in another reply.
The hall effect rotary sensor is one of these: BI TECHNOLOGIES / TT ELECTRONICS 6127V1A180L.5 SENSOR, HALL, 0.2V, +20V TO -10V, 180DEG.
It’s not quite a drop-in replacement as such. Or at least it wasn’t in my Cougar. My cougar delivered about 3.8v across the throttle pot. When in the circuit, the sensor didn’t work. Digging around the net it became clear that there is a resistor in series with the throttle pot and the switches on the stick. I had a look at the circuit and decided to break the connection between the resistor and the throttle pot but leave the connection intact to the rest of the throttle components. I then bypassed the resistor with a wire to supply the full 5v to the sensor.
The picture below shows the circuit board, the resistor and where to cut the track. I used a Dremel to cut the track.
Below shows the bypass wire:
The sensor is wired as follows:
+5v - orange
Vout- red
GND - brownThe sensor is mounted to a 90 degree 1-inch angle bracket. I bought mine from a local hardware store for about £1.25.
One hole was drilled out to 10mm to accept the hall effect sensor.
I purchased a servo arm from a local modellers shop. The shaft of the sensor is 6mm and so the servo arm needs to be drilled out accordingly. Unfortunately, I made the hole too large but compensated with plumbers PTFE tape. In hindsight that turned out well as I could mark the tape to indicate the centre position of the shaft and it also allowed room to adjust the arm when on the sensor shaft. The arm could then be tightened using the supplied grub screws.
The white tape is the plumber’s PTFE tape. The black mark is a marker pen.
At this stage, the bracket is not fixed in place. The whole assembly is upside down resting on some boxes to allow the handle to hang down centrally. I then turned the sensor shaft to get a rough central reading. This is done by using the HOTAS Cougar viewer application. Turn the shaft to obtain the maximum and minimum readings, then work out the halfway value and turn the shaft until the reading matches. Then mark the shaft with the pen. Obviously to do this the sensor must be wired up and plugged in. Make sure the sensor is firmly attached to the bracket.
The linkage between the servo arm and throttle is a couple of radio control ball studs and a steering linkage.
Something like this:
http://www.ebay.co.uk/itm/HPI-Ball-Stud-4-8x12mm-10pcs-86896-/391289473568?hash=item5b1aab8a20
I drilled a pilot hole about 2mm (don’t take my word for it though!) into the throttle shaft at the top dead centre with the throttle arms hanging straight down. Then I screwed one of the ball studs into the hole. The hole was just the right size to allow the stud to tap its own thread. Don’t overtighten! Notice in the picture below that the sensor is mounted the wrong way round. I didn’t realise this until testing and ended with a reversed throttle. Subsequent pictures show the correct orientation with the shaft pointing towards the inside of the case rather than the outside.
Next, assemble the steering linkage. Normally they do not come assembled but need the connectors screwing onto the threaded rod.
Mount the servo arm pointing straight up with the black mark on the shaft also at the top. Tighten the grub screws to clamp the arm in place.
Now mount the other ball stud into the servo arm and connect the steering linkage.
Finally, I decided to glue the bracket in place. I used a super glue gel. Time will tell if it will hold. There is no pressure on the sensor so hopefully, it will last. I chose glue as I didn’t want to drill the casing of the throttle and have an unsightly screw head on the top. The glue I used is Evo-Stick Serious Glue. It takes about 2 hours to set. Fully hardened in 24hrs. I have found this glue to be superb on children’s toys so I expect it to last.
So all you have to do now is let it set, then calibrate using the HOTAS Cougar Control Panel application.
CAUTION: the parts listed are not the parts I used except for the sensor, PTFE tape and glue. Order the rest at your own risk! I will try to find the exact parts and update the post when I have more time.
I have observed that there is a dead zone with this rig. At any position, when the throttle has not moved for a short period, you need to move it a fair bit before the change is registered. I’m not sure why this is. The linkage does not appear to have any play in it. I haven’t tried to use it for formation flying or in-flight refuelling (I need to train for that…). I might try a 90-degree sensor. The one that I used is a 180-degree sensor. The angular range of the throttle is about 90 degrees so I opted for more range just in case the rig would have hit a “wrap around” condition. I might swap for a 90-degree sensor when I have more time.I hope this has been of help to those in need of cubpilot’s hall effect sensor kit. Now you can make your own at a reasonable cost. Probably for much less than I did! Considering no changes to the throttle other than a track break, you can easily convert back to standard providing you haven’t blown anything up in the process
Update: This mod works with TUSBA. I don’t see any dead zones anymore - maybe something to do with the TUSBA but I doubt it. I can refuel with this mod and control the throttle to 1% increments.
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Nicely done!
Appreciate pics showing where the red/orange/brown wires from the hall sensor connect to.
For fastening of the bracket to the base, drill holes then use nuts/bolts would allow servicing/removal of the bracket in the future. For better long term hold, recommend something like QuikSteel instead of a super glue gel (http://www.quiksteel.co.uk/ ).
Thx,
f1 -
Thanks.
Did you need more photos of the wiring?
Thanks for the quick steel tip - I need to fix a handle on a kitchen tap and I think this will do the job better than the araldite that has failed.
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OK, very noon question… What is the hall sensor mod and what benefits would I get from it?
:oops:
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It replaces the potentiometer with a contactless magnetic solid state type of potentiometer that will not wear out. The pots supplied with the cougars are notorious for wearing out and causing spikes making inflight refuelling and formation flying very difficult.
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Thx scuba…
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Chaps,
I have observed that there is a dead zone with this rig. At any position, when the throttle has not moved for a short period, you need to move it a fair bit before the change is registered. I’m not sure why this is. The linkage does not appear to have any play in it. I haven’t tried to use it for formation flying or in flight refueling (I need to train for that…). I might try a 90 degree sensor. The one that I used is a 180 degree sensor. The angular range of the throttle is about 90 degrees so I opted for more range just in case the rig would have hit a “wrap around” condition. I might swap for 90 degree sensor when I have more time.
Any advance with this dead zone?
Thanks!
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Hi,
i ordered the same Part as 90 deg. (http://www.digikey.de/product-search/de?vendor=0&keywords=TT+ELECTRONICS+6127V1A90L.5)
want test this option.Report follow!
Blue
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Great Job with the mod. I’m fortunate to have the original cubby hall sensor, and never looked back…
I noted on your image the metal bushes replacing the original plastic throttle shaft bushes.
Can you tell me where you got them and if you think they are still available. Do they help with the stiction issue on the throttle.Ive used a piece of thin aluminium in a 'shovel shape, wrapped on the brake arm, and flat on the curve, to try reduce the stiction. Works but have to re-grease regularly.
Cheers.
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Hello Fish…. sorry for the late reply. The metal bushes were made by a chap in Australia. I have no idea if he still makes them or not. It was a very long time back. Do they help? I can’t really say. What I think did work was some special very low friction tape wrapped around the cylinder where the brake contacts. I have a large reel of this tape. Where are you? Maybe I can send you some. It need no lubrication and once applied you can forget about it.
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What kind of tape is that? I have access to just about any kind of tape on the planet. Low friction metallic tape?
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Teflon tape. Plumbers use it.
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@16th:
What kind of tape is that? I have access to just about any kind of tape on the planet. Low friction metallic tape?
It’s something like this. It’s blue backed. I bought it a long time ago and still have plenty left. It#s a clear tape once you peel the blue backing off.
If you find a supplier, just ask for a 1 meter sample.
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The tape is UHMW Ultra High Molecular Weight Polyethylene tape. Kinda like Plumbers tape….but more resistant to abrasion.
Scuba, I have a couple questions:
Have you figured out the dead zone in movement of your throttle with this mod?
Do you think that all Throttle PCB’s would require the same modification taking the resistor out of the Pot VE circuit?
Has your mounting bracket retained it’s integrity in regard to zero movement?And finally…how’s your Refueling skill coming along with your new mod?
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Truth is I’ve not spent much time on the sim since making modifying the throttle. But with you guys dragging the thread up a few times maybe I will try to find the time! Most of my time is spent writing articles about rare airguns these days.
The tape isn’t anything like plumbers tape from what I remember. I have a big reel of it. So if anyone what some, drop me a message and you can have some for just the cost of the postage/packing as I’m never going to use all of it.
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Perhaps I will do some inflight refuelling training this weekend as see how I get on.
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I was thinking about picking up some of those BI 6127 Hall sensors for quite a while, as they’re the ones that Sokol1 likes to use. The main holdup was figuring out how I was going to get a metal mounting bracket and a servo arm to mount it to the throttle, and I think you’ve just given me some valuable clues there. Just gotta find some US suppliers instead.
They’re not just something I need for the Cougar throttle, but also this A-10A throttle conversion project I haven’t finished for a few years.
As for the throttle mods, I had a set of UTM bushings once in my first Cougar; that was sold off a long time ago, only for me to go acquire another one after some withdrawal. Alas, I haven’t found another set of UTM bushings for sale; no tape needed, those things did the job perfectly regarding stiction elimination while keeping the whole thing smooth.
The problem is that nobody other than Ian Johnston can be bothered to make them, and as such, they’ve been out of production like the U2-NXT. For a simple bit of precision machined metal, they’re sure not easy to come by.
That said, I could give the tape a shot, something that should eliminate the “stiction” while adding a bit of damping so it doesn’t feel like I’m moving a wet noodle past the static friction point.
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I modded my throttle in a similar way to Scubapics . Rather than mounting a link ball on the throttle shaft I took the output shaft from a dead rc servo removed the gear and machined it to the same size and shape as the original pot shaft. With the tqs upsidedown with the handle at or very near the middle of it’s travel,I inserted the modded servo shaft into the original hole formerly occupied by the pot. Installed a 1" long servo arm in a vertical position. The whole affair fits neatly between the throttle shaft and the original pot mount. Install an identical servo arm on the hall sensor. Link balls mount on both arms at the 3/4" holes. Used a timed out linkage from my rc heli to connect.
I’ll try and get some pics . It actually turned out better than it sounds and I use 99.9% of the sensor’s travel split between max and min throttleDave
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I modded my throttle in a similar way to Scubapics . Rather than mounting a link ball on the throttle shaft I took the output shaft from a dead rc servo removed the gear and machined it to the same size and shape as the original pot shaft. With the tqs upsidedown with the handle at or very near the middle of it’s travel,I inserted the modded servo shaft into the original hole formerly occupied by the pot. Installed a 1" long servo arm in a vertical position. The whole affair fits neatly between the throttle shaft and the original pot mount. Install an identical servo arm on the hall sensor. Link balls mount on both arms at the 3/4" holes. Used a timed out linkage from my rc heli to connect.
I’ll try and get some pics . It actually turned out better than it sounds and I use 99.9% of the sensor’s travel split between max and min throttleDave
Please do post the pics man. I know it’s a PITA to do that, but as good as your description is, it’s still open to reader’s interpretation. Thanks man.
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Yeah about that. Sorry for the crappy cell phone pics
I used a Novotechnic RSC 2821-110-241-101 sensor ,one of a handful that I “harvested” from a dead case packing machine. A little large but it does fit and works well. Natively 5vdc supply so no issues with the cougar electrics. In the Foxy axis viewer app throttle is smooth as butter,in the pit I can adjust power by increments of 1lb if I am gentle
To set the position of the sensor bracket I installed the linkage, set both the throttle and the sensor to their mid points and used JB Weld to attach the sensor bracket to the TQS base.T fine tune the position I rotate the sensor in it’s bracket so the zero position of the sensor and the throttle coincide
Dave