Looking for 360 degree (only) Servo

[Michael Gardner]

I'm looking for a medium heavy servo (like Hitec 715 or 725) with a
travel of at least 340 degrees. A winch servo like the 725 doesn't work
because its designed to make about 7 full turns for a full range of
pulse widths - making the position resolution pretty sloppy within one
rotation. Yes, I can do gears or install an external potentiometer - I
was just hoping to find a servo I could use without modification but my
web surfing isn't turning one up.

Any pointers to manufacturer/model would be appreciated.
tnx
mgg

[me]

I've got an FP-S136G. Its a futaba retract servo.

Will that work?


"Michael Gardner" <> wrote in message
news:mgg-E9FC04.16135011122003@wildfire.prairienet.org...
> I'm looking for a medium heavy servo (like Hitec 715 or 725) with a
> travel of at least 340 degrees. A winch servo like the 725 doesn't work
> because its designed to make about 7 full turns for a full range of
> pulse widths - making the position resolution pretty sloppy within one
> rotation. Yes, I can do gears or install an external potentiometer - I
> was just hoping to find a servo I could use without modification but my
> web surfing isn't turning one up.
>
> Any pointers to manufacturer/model would be appreciated.
> tnx
> mgg

[Paul McIntosh]

If you let us in on what you are trying to do, maybe someone here can come
up with an elegant solution.

--
Paul McIntosh
Desert Sky Model Aviation
http://fly.mcintoshcentral.com
"Michael Gardner" <mgg@prairienet.org> wrote in message
news:mgg-E9FC04.16135011122003@wildfire.prairienet.org...
> I'm looking for a medium heavy servo (like Hitec 715 or 725) with a
> travel of at least 340 degrees. A winch servo like the 725 doesn't work
> because its designed to make about 7 full turns for a full range of
> pulse widths - making the position resolution pretty sloppy within one
> rotation. Yes, I can do gears or install an external potentiometer - I
> was just hoping to find a servo I could use without modification but my
> web surfing isn't turning one up.
>
> Any pointers to manufacturer/model would be appreciated.
> tnx
> mgg

[David AMA40795 / KC5UH]

Go to servocity.com and look at Hitec servos. It is not listed in the
chart, but if you pick a servo, the description lists whether 360
modifiable or not - example, HS-425BB, 700BB and 705MG servos are and
HS-81 isn't. I do not know what's involved, but an email to Servocity
will get you an answer.

David

On Thu, 11 Dec 2003 16:13:50 -0600, Michael Gardner
<mgg@prairienet.org> wrote:

>I'm looking for a medium heavy servo (like Hitec 715 or 725) with a
>travel of at least 340 degrees. A winch servo like the 725 doesn't work
>because its designed to make about 7 full turns for a full range of
>pulse widths - making the position resolution pretty sloppy within one
>rotation. Yes, I can do gears or install an external potentiometer - I
>was just hoping to find a servo I could use without modification but my
>web surfing isn't turning one up.
>
>Any pointers to manufacturer/model would be appreciated.
>tnx
>mgg

[David AMA40795 / KC5UH]

Go to servocity.com and look at Hitec servos. It is not listed in the
chart, but if you pick a servo, the description lists whether 360
modifiable or not - example, HS-425BB, 700BB and 705MG servos are and
HS-81 isn't. I do not know what's involved, but an email to Servocity
will get you an answer.

David

On Thu, 11 Dec 2003 16:13:50 -0600, Michael Gardner
<mgg@prairienet.org> wrote:

>I'm looking for a medium heavy servo (like Hitec 715 or 725) with a
>travel of at least 340 degrees. A winch servo like the 725 doesn't work
>because its designed to make about 7 full turns for a full range of
>pulse widths - making the position resolution pretty sloppy within one
>rotation. Yes, I can do gears or install an external potentiometer - I
>was just hoping to find a servo I could use without modification but my
>web surfing isn't turning one up.
>
>Any pointers to manufacturer/model would be appreciated.
>tnx
>mgg

[Michael Gardner]

In article <3fd92e3d.15511690@netnews.comcast.net>,
#$%^ham2405@yahoo.com (David AMA40795 / KC5UH) wrote:

> Go to servocity.com and look at Hitec servos. It is not listed in the
> chart, but if you pick a servo, the description lists whether 360
> modifiable or not - example, HS-425BB, 700BB and 705MG servos are and
> HS-81 isn't. I do not know what's involved, but an email to Servocity
> will get you an answer.
>

tnx, but the common "360 servo mod" is to turn the servo into geared
reversible DC motor, easily controlled via a standard RC receiver. the
geard potentiometer is replace with a resister bridge. I want position
controlled nearly 360 degree movement. That takes a specially built
single turn potentiometer or a multi-turn potentiometer with just the
right resistance range.

As for the question about what I want to do - I've spent a lot of time
thinking about good ways to do this - and finding the right servo if it
exists is the simplest solution. Changing out the pot in the servo with
a different multi-turn one with the right resistance range to get just
over one turn would be the next best solution. What am I trying to make
- well think light weight pan tilt zoom - except most PTZ units only
rotate around 180 degrees.

I'll pop servo city an email though and see if they can shed any light.
tnx
mgg

> David
>
> On Thu, 11 Dec 2003 16:13:50 -0600, Michael Gardner
> <mgg@prairienet.org> wrote:
>
> >I'm looking for a medium heavy servo (like Hitec 715 or 725) with a
> >travel of at least 340 degrees. A winch servo like the 725 doesn't work
> >because its designed to make about 7 full turns for a full range of
> >pulse widths - making the position resolution pretty sloppy within one
> >rotation. Yes, I can do gears or install an external potentiometer - I
> >was just hoping to find a servo I could use without modification but my
> >web surfing isn't turning one up.
> >
> >Any pointers to manufacturer/model would be appreciated.
> >tnx
> >mgg
>

[Michael Gardner]

In article <3fd92e3d.15511690@netnews.comcast.net>,
#$%^ham2405@yahoo.com (David AMA40795 / KC5UH) wrote:

> Go to servocity.com and look at Hitec servos. It is not listed in the
> chart, but if you pick a servo, the description lists whether 360
> modifiable or not - example, HS-425BB, 700BB and 705MG servos are and
> HS-81 isn't. I do not know what's involved, but an email to Servocity
> will get you an answer.
>

tnx, but the common "360 servo mod" is to turn the servo into geared
reversible DC motor, easily controlled via a standard RC receiver. the
geard potentiometer is replace with a resister bridge. I want position
controlled nearly 360 degree movement. That takes a specially built
single turn potentiometer or a multi-turn potentiometer with just the
right resistance range.

As for the question about what I want to do - I've spent a lot of time
thinking about good ways to do this - and finding the right servo if it
exists is the simplest solution. Changing out the pot in the servo with
a different multi-turn one with the right resistance range to get just
over one turn would be the next best solution. What am I trying to make
- well think light weight pan tilt zoom - except most PTZ units only
rotate around 180 degrees.

I'll pop servo city an email though and see if they can shed any light.
tnx
mgg

> David
>
> On Thu, 11 Dec 2003 16:13:50 -0600, Michael Gardner
> <mgg@prairienet.org> wrote:
>
> >I'm looking for a medium heavy servo (like Hitec 715 or 725) with a
> >travel of at least 340 degrees. A winch servo like the 725 doesn't work
> >because its designed to make about 7 full turns for a full range of
> >pulse widths - making the position resolution pretty sloppy within one
> >rotation. Yes, I can do gears or install an external potentiometer - I
> >was just hoping to find a servo I could use without modification but my
> >web surfing isn't turning one up.
> >
> >Any pointers to manufacturer/model would be appreciated.
> >tnx
> >mgg
>

[A.T.]

refer to http://homepages.ihug.co.nz/~atong/
= Alan's Hobby, Model & RC Web Links
and scroll down the headers to
"Servo & TX alterations, calculators, clonepacs, make an ESC or winch, FAQ."
in particular "Servo mods to 180 and 360 degree operation.. Gang and Fit
servos " http://www.amya.org/us1mpt4.pdf [16 page PDF download]
regards
Alan T.

Alan's Hobby, Model & RC Links
http://homepages.ihug.co.nz/~atong/
.................................................. ............





"Michael Gardner" <mgg@prairienet.org> wrote in message
news:mgg-E9FC04.16135011122003@wildfire.prairienet.org...
> I'm looking for a medium heavy servo (like Hitec 715 or 725) with a
> travel of at least 340 degrees. A winch servo like the 725 doesn't work
> because its designed to make about 7 full turns for a full range of
> pulse widths - making the position resolution pretty sloppy within one
> rotation. Yes, I can do gears or install an external potentiometer - I
> was just hoping to find a servo I could use without modification but my
> web surfing isn't turning one up.
>
> Any pointers to manufacturer/model would be appreciated.
> tnx
> mgg

[A.T.]

refer to http://homepages.ihug.co.nz/~atong/
= Alan's Hobby, Model & RC Web Links
and scroll down the headers to
"Servo & TX alterations, calculators, clonepacs, make an ESC or winch, FAQ."
in particular "Servo mods to 180 and 360 degree operation.. Gang and Fit
servos " http://www.amya.org/us1mpt4.pdf [16 page PDF download]
regards
Alan T.

Alan's Hobby, Model & RC Links
http://homepages.ihug.co.nz/~atong/
.................................................. ............





"Michael Gardner" <mgg@prairienet.org> wrote in message
news:mgg-E9FC04.16135011122003@wildfire.prairienet.org...
> I'm looking for a medium heavy servo (like Hitec 715 or 725) with a
> travel of at least 340 degrees. A winch servo like the 725 doesn't work
> because its designed to make about 7 full turns for a full range of
> pulse widths - making the position resolution pretty sloppy within one
> rotation. Yes, I can do gears or install an external potentiometer - I
> was just hoping to find a servo I could use without modification but my
> web surfing isn't turning one up.
>
> Any pointers to manufacturer/model would be appreciated.
> tnx
> mgg

[John Hawkins]

What about a PIC between the receiver and servo that takes 1~2
ms input and outputs a suitable amount of steps for the pulse range
that equals 360º? The PIC experimenters could probably code that up
fairly readily.




On Thu, 11 Dec 2003 16:13:50 -0600, Michael Gardner
<mgg@prairienet.org> wrote:

>I'm looking for a medium heavy servo (like Hitec 715 or 725) with a
>travel of at least 340 degrees. A winch servo like the 725 doesn't work
>because its designed to make about 7 full turns for a full range of
>pulse widths - making the position resolution pretty sloppy within one
>rotation. Yes, I can do gears or install an external potentiometer - I
>was just hoping to find a servo I could use without modification but my
>web surfing isn't turning one up.
>
>Any pointers to manufacturer/model would be appreciated.
>tnx
>mgg


John Hawkins - From Canada's Atlantic Coast
http://rcalbum.rchomepage.com/Home.html

[John Hawkins]

What about a PIC between the receiver and servo that takes 1~2
ms input and outputs a suitable amount of steps for the pulse range
that equals 360º? The PIC experimenters could probably code that up
fairly readily.




On Thu, 11 Dec 2003 16:13:50 -0600, Michael Gardner
<mgg@prairienet.org> wrote:

>I'm looking for a medium heavy servo (like Hitec 715 or 725) with a
>travel of at least 340 degrees. A winch servo like the 725 doesn't work
>because its designed to make about 7 full turns for a full range of
>pulse widths - making the position resolution pretty sloppy within one
>rotation. Yes, I can do gears or install an external potentiometer - I
>was just hoping to find a servo I could use without modification but my
>web surfing isn't turning one up.
>
>Any pointers to manufacturer/model would be appreciated.
>tnx
>mgg


John Hawkins - From Canada's Atlantic Coast
http://rcalbum.rchomepage.com/Home.html

[Michael Gardner]

In article <brc4n0$244$1@lust.ihug.co.nz>, "A.T." <atong@ihug.co.nz>
wrote:

> refer to http://homepages.ihug.co.nz/~atong/
> = Alan's Hobby, Model & RC Web Links
> and scroll down the headers to
> "Servo & TX alterations, calculators, clonepacs, make an ESC or winch, FAQ."
> in particular "Servo mods to 180 and 360 degree operation.. Gang and Fit

That might have been correct at one time, but it isn't today.

I have a 715 - and the pot in it has its own internal travel limit.
Turns about 200 degrees. If I added resistance to make the server want
to travel 360, it would simply tear the guts out of the pot. The pot
does look fairly standard though, so I expect I can replace it with
something that will do what I want.
tnx
mgg

> servos " http://www.amya.org/us1mpt4.pdf [16 page PDF download]
> regards
> Alan T.
>
> Alan's Hobby, Model & RC Links
> http://homepages.ihug.co.nz/~atong/
> .................................................. ...........
>
>
>
>
>
> "Michael Gardner" <mgg@prairienet.org> wrote in message
> news:mgg-E9FC04.16135011122003@wildfire.prairienet.org...
> > I'm looking for a medium heavy servo (like Hitec 715 or 725) with a
> > travel of at least 340 degrees. A winch servo like the 725 doesn't work
> > because its designed to make about 7 full turns for a full range of
> > pulse widths - making the position resolution pretty sloppy within one
> > rotation. Yes, I can do gears or install an external potentiometer - I
> > was just hoping to find a servo I could use without modification but my
> > web surfing isn't turning one up.
> >
> > Any pointers to manufacturer/model would be appreciated.
> > tnx
> > mgg
>
>
--
Real Working Engineer

[Michael Gardner]

In article <brc4n0$244$1@lust.ihug.co.nz>, "A.T." <atong@ihug.co.nz>
wrote:

> refer to http://homepages.ihug.co.nz/~atong/
> = Alan's Hobby, Model & RC Web Links
> and scroll down the headers to
> "Servo & TX alterations, calculators, clonepacs, make an ESC or winch, FAQ."
> in particular "Servo mods to 180 and 360 degree operation.. Gang and Fit

That might have been correct at one time, but it isn't today.

I have a 715 - and the pot in it has its own internal travel limit.
Turns about 200 degrees. If I added resistance to make the server want
to travel 360, it would simply tear the guts out of the pot. The pot
does look fairly standard though, so I expect I can replace it with
something that will do what I want.
tnx
mgg

> servos " http://www.amya.org/us1mpt4.pdf [16 page PDF download]
> regards
> Alan T.
>
> Alan's Hobby, Model & RC Links
> http://homepages.ihug.co.nz/~atong/
> .................................................. ...........
>
>
>
>
>
> "Michael Gardner" <mgg@prairienet.org> wrote in message
> news:mgg-E9FC04.16135011122003@wildfire.prairienet.org...
> > I'm looking for a medium heavy servo (like Hitec 715 or 725) with a
> > travel of at least 340 degrees. A winch servo like the 725 doesn't work
> > because its designed to make about 7 full turns for a full range of
> > pulse widths - making the position resolution pretty sloppy within one
> > rotation. Yes, I can do gears or install an external potentiometer - I
> > was just hoping to find a servo I could use without modification but my
> > web surfing isn't turning one up.
> >
> > Any pointers to manufacturer/model would be appreciated.
> > tnx
> > mgg
>
>
--
Real Working Engineer

[B McNeal]

I had a similar problem when installing the Hitec drum type servo winch into
my sailboat. What I finally ended up doing was installing a physical stop on
my transmitter stick to prevent the servo from overwinding. Limit the stick
movement and you limit the servo movement. Cheap and effective.

Bill McNeal
http://nfloridaorcas.freeservers.com


Michael Gardner wrote:

> I'm looking for a medium heavy servo (like Hitec 715 or 725) with a
> travel of at least 340 degrees. A winch servo like the 725 doesn't work
> because its designed to make about 7 full turns for a full range of
> pulse widths - making the position resolution pretty sloppy within one
> rotation. Yes, I can do gears or install an external potentiometer - I
> was just hoping to find a servo I could use without modification but my
> web surfing isn't turning one up.
>
> Any pointers to manufacturer/model would be appreciated.
> tnx
> mgg

[B McNeal]

I had a similar problem when installing the Hitec drum type servo winch into
my sailboat. What I finally ended up doing was installing a physical stop on
my transmitter stick to prevent the servo from overwinding. Limit the stick
movement and you limit the servo movement. Cheap and effective.

Bill McNeal
http://nfloridaorcas.freeservers.com


Michael Gardner wrote:

> I'm looking for a medium heavy servo (like Hitec 715 or 725) with a
> travel of at least 340 degrees. A winch servo like the 725 doesn't work
> because its designed to make about 7 full turns for a full range of
> pulse widths - making the position resolution pretty sloppy within one
> rotation. Yes, I can do gears or install an external potentiometer - I
> was just hoping to find a servo I could use without modification but my
> web surfing isn't turning one up.
>
> Any pointers to manufacturer/model would be appreciated.
> tnx
> mgg

[Chris Dugan]

"Michael Gardner" <mgg@prairienet.org> wrote in message
news:mgg-60AD2A.21410711122003@wildfire.prairienet.org...
> In article <3fd92e3d.15511690@netnews.comcast.net>,
> #$%^ham2405@yahoo.com (David AMA40795 / KC5UH) wrote:
>
> > Go to servocity.com and look at Hitec servos. It is not listed in the
> > chart, but if you pick a servo, the description lists whether 360
> > modifiable or not - example, HS-425BB, 700BB and 705MG servos are and
> > HS-81 isn't. I do not know what's involved, but an email to Servocity
> > will get you an answer.
> >
>
> tnx, but the common "360 servo mod" is to turn the servo into geared
> reversible DC motor, easily controlled via a standard RC receiver. the
> geard potentiometer is replace with a resister bridge. I want position
> controlled nearly 360 degree movement. That takes a specially built
> single turn potentiometer or a multi-turn potentiometer with just the
> right resistance range.
>
> As for the question about what I want to do - I've spent a lot of time
> thinking about good ways to do this - and finding the right servo if it
> exists is the simplest solution. Changing out the pot in the servo with
> a different multi-turn one with the right resistance range to get just
> over one turn would be the next best solution. What am I trying to make
> - well think light weight pan tilt zoom - except most PTZ units only
> rotate around 180 degrees.
>
> I'll pop servo city an email though and see if they can shed any light.
> tnx
> mgg
>
> > David
> >
David,

why not try changing the existing pot for a multiturn as you first thought
(the resistance isn't that important it's the voltage that is used to sense
the direction) and add in two fixed or variable resistors at either end so
you can adjust the endpoints?

Chris


---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.551 / Virus Database: 343 - Release Date: 11/12/2003

[Chris Dugan]

"Michael Gardner" <mgg@prairienet.org> wrote in message
news:mgg-60AD2A.21410711122003@wildfire.prairienet.org...
> In article <3fd92e3d.15511690@netnews.comcast.net>,
> #$%^ham2405@yahoo.com (David AMA40795 / KC5UH) wrote:
>
> > Go to servocity.com and look at Hitec servos. It is not listed in the
> > chart, but if you pick a servo, the description lists whether 360
> > modifiable or not - example, HS-425BB, 700BB and 705MG servos are and
> > HS-81 isn't. I do not know what's involved, but an email to Servocity
> > will get you an answer.
> >
>
> tnx, but the common "360 servo mod" is to turn the servo into geared
> reversible DC motor, easily controlled via a standard RC receiver. the
> geard potentiometer is replace with a resister bridge. I want position
> controlled nearly 360 degree movement. That takes a specially built
> single turn potentiometer or a multi-turn potentiometer with just the
> right resistance range.
>
> As for the question about what I want to do - I've spent a lot of time
> thinking about good ways to do this - and finding the right servo if it
> exists is the simplest solution. Changing out the pot in the servo with
> a different multi-turn one with the right resistance range to get just
> over one turn would be the next best solution. What am I trying to make
> - well think light weight pan tilt zoom - except most PTZ units only
> rotate around 180 degrees.
>
> I'll pop servo city an email though and see if they can shed any light.
> tnx
> mgg
>
> > David
> >
David,

why not try changing the existing pot for a multiturn as you first thought
(the resistance isn't that important it's the voltage that is used to sense
the direction) and add in two fixed or variable resistors at either end so
you can adjust the endpoints?

Chris


---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.551 / Virus Database: 343 - Release Date: 11/12/2003

[Paul McIntosh]

Most servos I have looked into have mechanical stops at around 190-200
degrees of total travel. Same with the pots as most modern servos have
direct drive pots. At best, those will allow about 250-280 degrees.

--
Paul McIntosh
Desert Sky Model Aviation
http://fly.mcintoshcentral.com
"John Hawkins" <parklane@accesswave.ca> wrote in message
news:ndfjtv88v1pi10muqgpt8amjp0ccht5no8@4ax.com...
> What about a PIC between the receiver and servo that takes 1~2
> ms input and outputs a suitable amount of steps for the pulse range
> that equals 360º? The PIC experimenters could probably code that up
> fairly readily.
>
>
>
>
> On Thu, 11 Dec 2003 16:13:50 -0600, Michael Gardner
> <mgg@prairienet.org> wrote:
>
> >I'm looking for a medium heavy servo (like Hitec 715 or 725) with a
> >travel of at least 340 degrees. A winch servo like the 725 doesn't work
> >because its designed to make about 7 full turns for a full range of
> >pulse widths - making the position resolution pretty sloppy within one
> >rotation. Yes, I can do gears or install an external potentiometer - I
> >was just hoping to find a servo I could use without modification but my
> >web surfing isn't turning one up.
> >
> >Any pointers to manufacturer/model would be appreciated.
> >tnx
> >mgg
>
>
> John Hawkins - From Canada's Atlantic Coast
> http://rcalbum.rchomepage.com/Home.html
>

[Paul McIntosh]

Most servos I have looked into have mechanical stops at around 190-200
degrees of total travel. Same with the pots as most modern servos have
direct drive pots. At best, those will allow about 250-280 degrees.

--
Paul McIntosh
Desert Sky Model Aviation
http://fly.mcintoshcentral.com
"John Hawkins" <parklane@accesswave.ca> wrote in message
news:ndfjtv88v1pi10muqgpt8amjp0ccht5no8@4ax.com...
> What about a PIC between the receiver and servo that takes 1~2
> ms input and outputs a suitable amount of steps for the pulse range
> that equals 360º? The PIC experimenters could probably code that up
> fairly readily.
>
>
>
>
> On Thu, 11 Dec 2003 16:13:50 -0600, Michael Gardner
> <mgg@prairienet.org> wrote:
>
> >I'm looking for a medium heavy servo (like Hitec 715 or 725) with a
> >travel of at least 340 degrees. A winch servo like the 725 doesn't work
> >because its designed to make about 7 full turns for a full range of
> >pulse widths - making the position resolution pretty sloppy within one
> >rotation. Yes, I can do gears or install an external potentiometer - I
> >was just hoping to find a servo I could use without modification but my
> >web surfing isn't turning one up.
> >
> >Any pointers to manufacturer/model would be appreciated.
> >tnx
> >mgg
>
>
> John Hawkins - From Canada's Atlantic Coast
> http://rcalbum.rchomepage.com/Home.html
>

[Paul McIntosh]

I am afraid that servos don't work like that. You need to get the right
resistance /rotation ratio and adding resistors won't do that.

His best bet is to get a tilt/pan setup designed for what he needs.
Anything else will be a kluge.

--
Paul McIntosh
Desert Sky Model Aviation
http://fly.mcintoshcentral.com
"Chris Dugan" <chrisdotdugan@bloodyobvious.co.uk> wrote in message
news:zjrCb.2103$526.13786@newsfep4-glfd.server.ntli.net...
> "Michael Gardner" <mgg@prairienet.org> wrote in message
> news:mgg-60AD2A.21410711122003@wildfire.prairienet.org...
> > In article <3fd92e3d.15511690@netnews.comcast.net>,
> > #$%^ham2405@yahoo.com (David AMA40795 / KC5UH) wrote:
> >
> > > Go to servocity.com and look at Hitec servos. It is not listed in the
> > > chart, but if you pick a servo, the description lists whether 360
> > > modifiable or not - example, HS-425BB, 700BB and 705MG servos are and
> > > HS-81 isn't. I do not know what's involved, but an email to Servocity
> > > will get you an answer.
> > >
> >
> > tnx, but the common "360 servo mod" is to turn the servo into geared
> > reversible DC motor, easily controlled via a standard RC receiver. the
> > geard potentiometer is replace with a resister bridge. I want position
> > controlled nearly 360 degree movement. That takes a specially built
> > single turn potentiometer or a multi-turn potentiometer with just the
> > right resistance range.
> >
> > As for the question about what I want to do - I've spent a lot of time
> > thinking about good ways to do this - and finding the right servo if it
> > exists is the simplest solution. Changing out the pot in the servo with
> > a different multi-turn one with the right resistance range to get just
> > over one turn would be the next best solution. What am I trying to make
> > - well think light weight pan tilt zoom - except most PTZ units only
> > rotate around 180 degrees.
> >
> > I'll pop servo city an email though and see if they can shed any light.
> > tnx
> > mgg
> >
> > > David
> > >
> David,
>
> why not try changing the existing pot for a multiturn as you first thought
> (the resistance isn't that important it's the voltage that is used to
sense
> the direction) and add in two fixed or variable resistors at either end so
> you can adjust the endpoints?
>
> Chris
>
>
> ---
> Outgoing mail is certified Virus Free.
> Checked by AVG anti-virus system (http://www.grisoft.com).
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>
>

[Paul McIntosh]

I am afraid that servos don't work like that. You need to get the right
resistance /rotation ratio and adding resistors won't do that.

His best bet is to get a tilt/pan setup designed for what he needs.
Anything else will be a kluge.

--
Paul McIntosh
Desert Sky Model Aviation
http://fly.mcintoshcentral.com
"Chris Dugan" <chrisdotdugan@bloodyobvious.co.uk> wrote in message
news:zjrCb.2103$526.13786@newsfep4-glfd.server.ntli.net...
> "Michael Gardner" <mgg@prairienet.org> wrote in message
> news:mgg-60AD2A.21410711122003@wildfire.prairienet.org...
> > In article <3fd92e3d.15511690@netnews.comcast.net>,
> > #$%^ham2405@yahoo.com (David AMA40795 / KC5UH) wrote:
> >
> > > Go to servocity.com and look at Hitec servos. It is not listed in the
> > > chart, but if you pick a servo, the description lists whether 360
> > > modifiable or not - example, HS-425BB, 700BB and 705MG servos are and
> > > HS-81 isn't. I do not know what's involved, but an email to Servocity
> > > will get you an answer.
> > >
> >
> > tnx, but the common "360 servo mod" is to turn the servo into geared
> > reversible DC motor, easily controlled via a standard RC receiver. the
> > geard potentiometer is replace with a resister bridge. I want position
> > controlled nearly 360 degree movement. That takes a specially built
> > single turn potentiometer or a multi-turn potentiometer with just the
> > right resistance range.
> >
> > As for the question about what I want to do - I've spent a lot of time
> > thinking about good ways to do this - and finding the right servo if it
> > exists is the simplest solution. Changing out the pot in the servo with
> > a different multi-turn one with the right resistance range to get just
> > over one turn would be the next best solution. What am I trying to make
> > - well think light weight pan tilt zoom - except most PTZ units only
> > rotate around 180 degrees.
> >
> > I'll pop servo city an email though and see if they can shed any light.
> > tnx
> > mgg
> >
> > > David
> > >
> David,
>
> why not try changing the existing pot for a multiturn as you first thought
> (the resistance isn't that important it's the voltage that is used to
sense
> the direction) and add in two fixed or variable resistors at either end so
> you can adjust the endpoints?
>
> Chris
>
>
> ---
> Outgoing mail is certified Virus Free.
> Checked by AVG anti-virus system (http://www.grisoft.com).
> Version: 6.0.551 / Virus Database: 343 - Release Date: 11/12/2003
>
>

[Kevin Russell]

>
> tnx, but the common "360 servo mod" is to turn the servo into geared
> reversible DC motor, easily controlled via a standard RC receiver. the
> geard potentiometer is replace with a resister bridge. I want position
> controlled nearly 360 degree movement. That takes a specially built
> single turn potentiometer or a multi-turn potentiometer with just the
> right resistance range.
>
> As for the question about what I want to do - I've spent a lot of time
> thinking about good ways to do this - and finding the right servo if it
> exists is the simplest solution. Changing out the pot in the servo with
> a different multi-turn one with the right resistance range to get just
> over one turn would be the next best solution. What am I trying to make
> - well think light weight pan tilt zoom - except most PTZ units only
> rotate around 180 degrees.
>
do you need control in the form of a servo? as most pan tilt units only have
on off motor control and they stay were you put them using no power


---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.551 / Virus Database: 343 - Release Date: 11/12/2003

[Kevin Russell]

>
> tnx, but the common "360 servo mod" is to turn the servo into geared
> reversible DC motor, easily controlled via a standard RC receiver. the
> geard potentiometer is replace with a resister bridge. I want position
> controlled nearly 360 degree movement. That takes a specially built
> single turn potentiometer or a multi-turn potentiometer with just the
> right resistance range.
>
> As for the question about what I want to do - I've spent a lot of time
> thinking about good ways to do this - and finding the right servo if it
> exists is the simplest solution. Changing out the pot in the servo with
> a different multi-turn one with the right resistance range to get just
> over one turn would be the next best solution. What am I trying to make
> - well think light weight pan tilt zoom - except most PTZ units only
> rotate around 180 degrees.
>
do you need control in the form of a servo? as most pan tilt units only have
on off motor control and they stay were you put them using no power


---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.551 / Virus Database: 343 - Release Date: 11/12/2003

[Chris]

I had this same problem with rotating gun turrets on a model warship. The
solution I ended up using was to mount an arm on the servo with fishing line
or similar tied to the ends to the ends, the loop formed is wound on a drum,
the camera mounted on the drum, this has the advantage of being light.
Another solution is to use a 3:1 or 4:1 gear ratio the larger gear mounted
on the servo, but this requires much more precision, or maybe a large pulley
on the servo driving a small pulley on the camera's rotation shaft.

Regards

Chris

--


-------------------------------------------------------------------------



"Michael Gardner" <mgg@prairienet.org> wrote in message
news:mgg-E9FC04.16135011122003@wildfire.prairienet.org...
> I'm looking for a medium heavy servo (like Hitec 715 or 725) with a
> travel of at least 340 degrees. A winch servo like the 725 doesn't work
> because its designed to make about 7 full turns for a full range of
> pulse widths - making the position resolution pretty sloppy within one
> rotation. Yes, I can do gears or install an external potentiometer - I
> was just hoping to find a servo I could use without modification but my
> web surfing isn't turning one up.
>
> Any pointers to manufacturer/model would be appreciated.
> tnx
> mgg

[Chris]

I had this same problem with rotating gun turrets on a model warship. The
solution I ended up using was to mount an arm on the servo with fishing line
or similar tied to the ends to the ends, the loop formed is wound on a drum,
the camera mounted on the drum, this has the advantage of being light.
Another solution is to use a 3:1 or 4:1 gear ratio the larger gear mounted
on the servo, but this requires much more precision, or maybe a large pulley
on the servo driving a small pulley on the camera's rotation shaft.

Regards

Chris

--


-------------------------------------------------------------------------



"Michael Gardner" <mgg@prairienet.org> wrote in message
news:mgg-E9FC04.16135011122003@wildfire.prairienet.org...
> I'm looking for a medium heavy servo (like Hitec 715 or 725) with a
> travel of at least 340 degrees. A winch servo like the 725 doesn't work
> because its designed to make about 7 full turns for a full range of
> pulse widths - making the position resolution pretty sloppy within one
> rotation. Yes, I can do gears or install an external potentiometer - I
> was just hoping to find a servo I could use without modification but my
> web surfing isn't turning one up.
>
> Any pointers to manufacturer/model would be appreciated.
> tnx
> mgg

[grizzlyone]

http://servohut.com/HTML/s125fullt.htm

May do the job...

Griz

[Michael Gardner]

In article <grizzlyone.z6y39@rcgroups.com>,
grizzlyone <grizzlyone.z6y39@rcgroups.com> wrote:

> http://servohut.com/HTML/s125fullt.htm

tnx

mgg
--
I have better things to do with my time that worry who might make fun of my sig.