RunRyder RC Helicopter Topic - What Servos are you using for Pan and Tilt????

RR Rated M For Mature

HOME rrTV-PHOTO GALLERIES MY GALLERY HELP-FAQ

myHOME PM pmRR MEMBERS 395 ONLINE 18 EVENTS SEARCH REGISTER START HERE

1 page

636 views

POST REPLY

Heli-Max	.	Hobby Hut	.	Heli Wholesaler
	.		.

Aerial Photography and Video > What Servos are you using for Pan and Tilt????

Jerryc
Senior Heliman
Location: Oklahoma City

My Posts This: Topic Forum

I'm using JR 8411's but there much to fast for any kind of smooth pan and tilt action. I need a strong but slow(er) servo. and yes, I'm working on the gearing issue. It's 1:1 now. and I need to make the servo have more throw (ie: 360 degrees).

Jerryc

02-19-2004 Over year old.

PROFILE PM EMAIL POSTS BUDDY IGNORE HOMEPAGE GALLERY

MPA
Elite Veteran
Location: Australia

My Posts This: Topic Forum

Jerry I dont think Servo rating speeds come into play as the would for the Heli tail for example.

You can bet that any standard servo driving 1:1 ratio will be too sensitive if it bears weigth or moves over centre and only suitable for triggering.

Changing servo rating speeds wont overcome the physics of that problem it is more the mass swinging on the servo that is the issue.

That means not good on pan, titl or roll. (X,Y,Z camera axis)
Too twitchy to control smoothly and probably suffer servo jitter.

The gearing with remote feedback POT gives you a good feel, reduces jitters and cost the price of a 5K POT and gears.

You can use a RC-Cam Pan setup but, more complex and may not be up your alley if your not inclined to electronics as a hobby.

02-19-2004 Over year old.

PROFILE PM EMAIL POSTS BUDDY IGNORE HOMEPAGE

Jerryc
Senior Heliman
Location: Oklahoma City

My Posts This: Topic Forum

"The gearing with remote feedback POT" what exactly do you mean by this? "remote feedback POT"??

Jerryc

02-19-2004 Over year old.

PROFILE PM EMAIL POSTS BUDDY IGNORE HOMEPAGE GALLERY

MPA
Elite Veteran
Location: Australia

My Posts This: Topic Forum

If you have a look inside the servo you will see a POT (potentiometer) inside.

You replicate that POT but on the outside if the servo and then use the external POT on the axis of the mount instead of the axis of the servo output shaft.

Here is a site to explain it more.
See method 2
http://www.fortunecity.com/marina/nelson/479/index.html

02-19-2004 Over year old.

PROFILE PM EMAIL POSTS BUDDY IGNORE HOMEPAGE

ELOSSAM
Veteran
Location: Es

My Posts This: Topic Forum

I was playing yesterday with the same principle you can see at
http://www.fortunecity.com/marina/nelson/479/index.html
but in my case the little pot was fixed so it can be directly adjusted by the output gear as the stock ones do. The only thing I need to to was to remove the old pot, disassemble it and use its shaft filed like a flat screw driver to act over the pot. This way you will keep the servo position as a stock one but as we can use different micro-multiturn pots you will have as many operational turns as you need only changing the pot. The ATV allows me to have from 90º to 10 x 360º

The bad side of it is that increasing the turn rate of the pots will give bad centering accuracy and a very slow turn rate near the center point when self centering.

Have tested 10 turn 5k pots and 1k pots too but cant notice any difference in use between both them. Next test will be to look for a 2 or 3 turns pot.

PD to do it , the best servo I found was the Robbe FS110BB very similar to the Futaba 3003 but with newest electronic, more free space inside. and cheaper (at least here) thant the 3003.

Pics ..... on monday

02-19-2004 Over year old.

PROFILE PM EMAIL POSTS BUDDY IGNORE HOMEPAGE GALLERY

MPA
Elite Veteran
Location: Australia

My Posts This: Topic Forum

Hi

I would advise not go under 5K.
Means higher consumption and more heat and serves no purpose.

The 5K value is not a reference to the pot sweep it merely dictates how much current is across the pot resistance bridge from ground to power and reducing the POT ohms just draws more current across it that it doesnt need to signal position.

Remember a POT is equall on both sides of the arm when in the centre.
When it is to one side of the sweep the difference from the other side resistance is the same ratio of difference in a 5K as for a 1K pot.

Example a POT with 180 degree sweep.
0 volt one side and 12 volts the other side.

In the centre at 90 degree a 5k POT is 2.5K each side
A 1K POT is 500R each side
Both cases half the voltage 6V to the servo position feedback input, to it the servo is half way.

At 45 degree to the side a 5K POT may be 1.25K and 3.75K on the other side.
A 1K POT at 45 deg would be say 250R on one side and 750R on the other side.

So in the 5K POT, 45 deg to the 0 side is 1/4 + of the 12v voltage to one side, 3V
OR 45 deg to the 12volt side is 3/4 of 12V, 9V

Same for 1K POT at 45 deg.
3V or 9 V at 45 degreee each side of centre.

Just the 1K POT has more current over the resitance bridge in the POT.
There is no more current going to the servo position feedback input as that draws no current, the chip it only reads the voltage present and compares it to current max voltage to tell where the servo is.

OTH 10K may result in too little over the servo POT resitance bridge and then it may be subject to more interference due to less current over it.

Number of turns is up to you but resistance
Leave it at 5K or the equivelant of the POT that came out of the servo.

02-19-2004 Over year old.

PROFILE PM EMAIL POSTS BUDDY IGNORE HOMEPAGE

ELOSSAM
Veteran
Location: Es

My Posts This: Topic Forum

MPA , Have test a 10k pot the same way as the others but the servo suffer lot of stress and didn´t work. Have also break one of those little pots to see how was it made and seems to have lot of free play inside (there are not multi-turn precision pots like the others I use) . May be with a 2 to 3 turns pots things goes better.

02-19-2004 Over year old.

PROFILE PM EMAIL POSTS BUDDY IGNORE HOMEPAGE GALLERY

MPA
Elite Veteran
Location: Australia

My Posts This: Topic Forum

Thanks Elossam
That answer the result of using a 10K

I have not tried a multi turn POT but may give it a go.

Cheers

02-20-2004 Over year old.

PROFILE PM EMAIL POSTS BUDDY IGNORE HOMEPAGE

ELOSSAM
Veteran
Location: Es

My Posts This: Topic Forum

MPA look for the best quality multiturn pot you can find at 5K and may be around 3 turns, that will give you nice results but due to its size (not available in micro-size with nice accuracy) you will need to use it out of the servo.

02-20-2004 Over year old.

PROFILE PM EMAIL POSTS BUDDY IGNORE HOMEPAGE GALLERY

ELOSSAM
Veteran
Location: Es

My Posts This: Topic Forum

The one I used before the micro size experiments is the 166-4431 from this web. Sorry for the long address

http://www.amidata.es/cgi-bin/bv/br...toid=-286735371

02-20-2004 Over year old.

PROFILE PM EMAIL POSTS BUDDY IGNORE HOMEPAGE GALLERY

Glenn in Den
Key Veteran
Location: Longmont, Colorado area

My Posts This: Topic Forum

What about just using retract servos like the JR 513 ?

Glenn.

I'm not really an R/C pilot, I stayed in a Holiday Inn Express last n

02-20-2004 Over year old.

PROFILE PM EMAIL POSTS BUDDY IGNORE

MPA
Elite Veteran
Location: Australia

My Posts This: Topic Forum

Not sure, if I remember right, it's because retract servos cost a pile more than std servos, cheaper to convert a std one I think.

02-20-2004 Over year old.

PROFILE PM EMAIL POSTS BUDDY IGNORE HOMEPAGE

Glenn in Den
Key Veteran
Location: Longmont, Colorado area

My Posts This: Topic Forum

I just bought 2 from my LHS for $32 each. That doesn't seem too bad.

Glenn.

I'm not really an R/C pilot, I stayed in a Holiday Inn Express last n

02-20-2004 Over year old.

PROFILE PM EMAIL POSTS BUDDY IGNORE

1 page

636 views

POST REPLY

JR-Spektrum	.	E-flite	.	Fast Lad Performance
	.		.

Aerial Photography and Video > What Servos are you using for Pan and Tilt????

Print TOPIC

Advertisers

Subscribe to This Topic