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Jul 30, 2008, 10:54 PM
my karma ranover my dogma
galaxiex's Avatar
Quote:
Originally Posted by randall1959
Well, since my new radio hasn't arrived yet, and I have only ever used channel 6 for pan anyway, I decided to crack open my Prizm 7X and cut the wires to that pot and added a servo lead. Being mindfull of the position of the center wire, I then added the corresponding connector to the gymbal. Either it's because I am using a Futaba Gymbal on a Hitec radio, or something else, even at full deflection of the gymbal, I'm probably only getting 20 degrees of movement, total.
http://www.vimeo.com/1440198
On my radio, I've got all the epa's set out to 125% It also appears that the knob rotates much farther than the gymbal will allow it's pot to rotate so I'm going to have to look into some means of fixing that.
Just a thought... did you compare/measure the resistances of the gimbal pot and the flap pot?
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Jul 30, 2008, 11:04 PM
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No I haven't. Either way, the way this is working won't help much. I might have to go back to simpler 3 channel flight and use channel 4 in order for the gymbal to give me enough movement.
Jul 30, 2008, 11:09 PM
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The pot on the flap switch on the tx has .9 something and the pot on the gymbal has .3 something. There is much more resistance on the gymbal is what I'm getting. Like 3 times as much.
Jul 30, 2008, 11:16 PM
my karma ranover my dogma
galaxiex's Avatar
Hmmm, that would explain the reduced travel.

if you can find a pot that fits your gimbal, or a different gimbal with resistance closer to what the flap pot measures, that would help...
Jul 30, 2008, 11:25 PM
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I found the answer to my problem I got a servo extender from servo city
Jul 30, 2008, 11:28 PM
my karma ranover my dogma
galaxiex's Avatar
Ahhh yes, that would work.
Jul 30, 2008, 11:32 PM
Registered User
Daemon's Avatar
If you'd read the thread I linked earlier, you'd learn that you can't
measure the resistance of one pot versus another and have it mean anything
at all. It'll range from seemingly meaningful to completely baffling, even
if the two pots work identically. All that matters is the voltage between the
signal wire and ground when a voltage is applied across the outside two
terminals and the pot is moved. For the most part the gymbal pot and flap pot
should give you the same total range.

You either need a servo extender, as you found, or a programmable
digital servo (such as the Hyperion Atlas series). The latter
will give you *much* greater precision.

ian
Jul 30, 2008, 11:47 PM
Suspended Account
Ok, but having said that, the one with the greatest resistance would allow less current to flow, which would also change things. The servo I have mounted in my Easy Star is probably there until I fly into something and break it loose The servo stretcher appears to be the least hassle to work with and less expensive. I'm not worried about great precision, just being able to look toward where I'm wanting to turn or to check out the area for hawks. Whether or not I read your thread in it's entirety, Daemon, I would probably still have tried this without the servo extender first, then went from there. If I had ordered the extender and found out later that I didn't need it that would have been twenty bucks more or less wasted.
In the meantime I'm working on a way to cut down this gymbal setup to just what's needed and I've really been able to cut a lot of the "junk" off it. Now I'm down to just one side of the entire gymbal setup. I've managed to retain the pot, the trim knob and the spring tensioner and the whole thing is only an inch thick as compared to that big plastic block.
I'm making progress
Jul 30, 2008, 11:47 PM
Just trying to get a nut.
scrtsqrl's Avatar
Quote:
Originally Posted by randall1959
It also appears that the knob rotates much farther than the gymbal will allow it's pot to rotate so I'm going to have to look into some means of fixing that.
This is the problem solved by having the bungy choord arranged as in my video...Because of the mechanical advantage of the pot (it is closer to the "fulcrum") one needs only to move his head slightly to get end point to end point movement of the pan servo.
Jul 30, 2008, 11:50 PM
Suspended Account
The bungee idea wouldn't have helped in this situation scrt. I had the lever all the way over and it only moved the camera ten degrees. I'm not running mine through the rudder channel. I'm running mine through the flap dial. That dial rotates almost 300 degrees. The gymbal rotates it's pot maybe twenty at most. The only other way to overcome that would be to use a gear setup to rotate the pot more.
Jul 31, 2008, 11:17 PM
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I ended up going to the front of the helmet I think. I tried various attaching methods, rods, levers and such on the back but couldn't get much movement and it was hard to move my head around much. So since I am only using pan, I removed the pot completely and put it on an L bracket, attached some fishing line to the arm, and tied a rubber band on the end of that and slipped it over my tx antenna. It actually does move the servo quite a bit more now but I still need more movement. I'm going to wait now until the servo stretcher gets here and also get one of those retractable things. They give em away to us at work for our keycards
I'll just have to get used to having this thing in front of me.
Jul 31, 2008, 11:20 PM
Registered User
hoysome's Avatar
your going with a servo stretcher, but a digital servo can also be programmed to do it
Jul 31, 2008, 11:22 PM
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But aren't digital servos rather expensive? How do you program them anyway?
Jul 31, 2008, 11:24 PM
Registered User
hoysome's Avatar
potentially, im not sure how much a regular servo + servo mod for extra radius costs, as I bought a digital with a 400mod already done on it
Aug 01, 2008, 05:01 PM
Suspended Account
Quote:
Originally Posted by scrtsqrl
This is the problem solved by having the bungy choord arranged as in my video...Because of the mechanical advantage of the pot (it is closer to the "fulcrum") one needs only to move his head slightly to get end point to end point movement of the pan servo.
I think also that it works better on the front as opposed to the back because on the back, without some sort of rod to hold it back a ways, it's right on your neck basically and on the front, it's around six inches or so from your neck.
Anyways, I made progress today. Got my ID card retractor today and I'm getting ready to attach it to the switch. I also need to figure out what to put on the end of my tx antenna. Something rubber or plastic. I'll have to look through my junk drawer


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