I have a pair of brand new Hitec 55's. I also have a tool called TXSERVO which is a little gizmo that you plug into a USB Port and can plug up to two servos into and then you can 'exercise' these servos. It comes with software that has a very simple movement program and a 'grid' that you can select movement and 'play' the movment back into the servos. Neat gadget.

Aaaanyway, I use it to zero servos, to make sure the gears are not stripped (I have one that is, and it sort of.. stutters.. for lack of a better term) and to check the maximum throw. I'm sure there are other applications, but those are the main ones I use.

I was just 'playing' with the servos with TXSERVO. As I said, I can plug two servos into this gadget, so I did. And, as I said, I have a pair of new HS-55's, and I plugged one in 'channel 1', and one in 'channel 2'. Then, when I used the grid to move both servos through their range of movement, I found that one was slower than the other.

I swapped the TXSERVO channels thinking that if it was a computer or a TXSERVO problem, then the other servo would be slower, but the same servo was slower, meaning that 'servo 2' was slower than 'servo 1'. If used on ailerons, for instance, one aileron would be slower to respond than the other, the difference was around 1 second, which could be considerable, if used on ailerons or any other application that uses two servos (ailerons or elevators, flaps, whatever).

I guess this is not a question, but an observation. Perhaps someone out there has a comment to offer about this. The only other solution I can think of is to use different manufactuer servos, or play with new servos until I find a pair that match, or not to worry about it at all.

What do you guys think?

CGr

I would use a matching pair on the ailerons

Put that slow one on the throttle of a glow engine?

w8ye

I totally agree.

What I found was that the tool, TXSERVO showed latency between the two servos. I switched them (the TXSERVO has "two channels") well, as it started out, servo 1 was in channel 1 and servo 2 was in channel 2 and tested them (tested the movement). Servo 2 seemed slower than servo 1. Then I put servo 1 in channel 2 and servo 2 in channel 1, and found that servo 2 was again slower than servo 1 (eyeball observation, nothing scientific here). The difference was perhaps one second. I guess I could time it electronically if I really wanted to, but my point is to inform new people (and some of our journeymen) of the fact that not all servos are alike.

For most of our applications, this probably won't matter. But, for some that may be comtemplating Pattern or 3D, well, the servos should match.

I've included a 'screen shot' of the TXSERVO software to show what the tool is capable of doing. The graph is a tool that you can click on and move the servo to that position. Note the values in the green background square. Centering the servo occurs at 1550,1550. The last position is slightly off, but it will center at 1550, 1550.

I guess what I am trying to point out here is that there are tools available to help you both center the servos, and test the difference in the "speed" (latency) of one servo against another. This helps select servos for use... ailerons (dual servo apps) or elevators (again, dual servo apps) or landing gear, or whatever.

Another point here is a tool that helps center servos. They all must be centered somehow, either with the TX or a tool like TXSERVO.
CGr

CGR,
Do you have a link to this???

ken

http://www.txservo.com/

i would use them on the aileron(if you must) you probably wont notice it, however on the elevators you probably will.... i would replace the slower servoits possible defective......, or if you must use it and dont fly 3d then i would use it on the rudder

Sounds like a very worth while piece of equipment. I could imagine myself, still pretty new at this, chasing centers and endpoints with my radio trying to fix a problem that could have been a mis-matched servo.

I wonder if/how this thing would work in combination with a programmer for digital servos?

The digital servo programmer does the same thing for a little more money but it has other capabilities also

Yeah, rudder or throttle. I've used the smaller servos for throttle on glow's before, does just fine. It does not require a lot of torque, provided you remove binds from the linkage (as with anything else).

w8ye:

I believe they (TXSERVO) hae a more advanced tool for their product, but I don't think it is a programmer for digitals. I don't know that, though, and I don't own any real digital servos, so I don't have a reason to find out. I do own some ball bearing, high torque, coreless types, mostly Airtronics, but no real "digital" servos.

What's nice about this gadget is that I can center the servo, then pick the right servo arm that gives me the perpendicular position that I want for most applications without having to play with the servo centering on the transmitter. I can set that to 0, then after I've already centered the servo itself, and picked the right servo arm, I'm good to go.

CGr.

as far as i know you need a hitec programmer to program hitec digital servos......1 servo per control surface and a good computer radio and no programmer is needed......however if you have multiple servos on a single control surface, and dont have a Smartfly or Match boxes then you would need a servo programmer

I think JR is coming out with a programmer for their digitals as well. The TXSERVO IMO is more of a fancy toy

It may be a fancy toy to some, but it does a nice job of centering the servos. And, I found a bad servo ( had broken teeth ) by exercising the servo from end to end with it. So, it's a bit more than a fancy toy for me. Since I don't own a digital servo, and probably will never own one, as I said, it does the job for me.