Bert
Dec 13, 2002, 04:07 PM
Adding resistors to the outside legs of the feedback pot is the easiest
solution. I've used 0 to 10K Ohm trimmers (Radio Shack # 271-282). They
are small enough to mount on a small perf board and still have room inside
the servo. Since they are adjustable you can set the travel exactly where
you want it. If the 10K does not give you enough travel, get the 47K
(#271-283). I am sure there is a limit to the number of drum turns this
winch can do. I can't remember how the feedback works in this winc but
there must be a limit.
The bigest problem with the Hitec winch is that it is so slow. That is
probably not important for your boat. Racing is a different story.
Here are some nice pictures and comments on the Atlantis.
http://www.a1-electronics.co.uk/General_Interest/Sailing.shtml
Another ajustable winch if the RMG winch from Australia. Depending on the
exchange rate, the cheapest one is about $125. They are very fast and
strong, but the gears are a little noisy.
I would be interested in anything you have found on decreasing the number of
turns for the Hitec drum winch. 4.5 turns is usually way to much travel for
the 1 meter boats this winch is useful on. I am now using a loop of string
which restricts the transmitter stick travel but would perfer to do it
electronically. I guess the thing to to is add resistors to the transmitter
pot.
Bert
"Rob" <purchasing@fansteelvrwesson.com> wrote in message
news:459cf7f6.0211271052.301bf8a2@posting.google.c om...
> Here's the question, with some options in the solution. This is a
> large sailboat (the Robbe Atlantis) and its genoa (very large
> foresail) is controlled by a dedicated drum-winch servo that has to
> drag a traveller the full length of a 48" (or so) track.
>
> Not having the $150 that Futaba wants for its S5801, I bought a HiTec
> HS725. This winch has more power than the Futaba, but its
> shortcomings include a lack of adjustability and high current draw at
> idle. But for a $100+ savings, I'm willing to mess around to get what
> I need.
>
> So: the drum has a 7 3/8" circumference. To get 48" of sheet travel
> I'm going to need the drum to make at least 6.5 turns. The winch's
> standard rotation is 3.5-4.5 and it depends on the transmitter. I can
> find any number of sites that tell me how to make a standard servo
> into a continuously rotating servo; how to make a 60 degree servo
> into a 90 degree one, or reduce the number of turns on a drumwinch
> servo.
>
> But I can't find a single one that will tell me how to increase the
> number of turns. The options are that I modify the receiver with
> adjustable pot (or pots) in the channel circuit, modify the servo with
> either resistors or pots in the feedback circuit, or throw my hands in
> the air and whine to the wife,"Gimme $150!" Not being fond of black
> eyes, I'll kindly ask you all if you can suggest something..
solution. I've used 0 to 10K Ohm trimmers (Radio Shack # 271-282). They
are small enough to mount on a small perf board and still have room inside
the servo. Since they are adjustable you can set the travel exactly where
you want it. If the 10K does not give you enough travel, get the 47K
(#271-283). I am sure there is a limit to the number of drum turns this
winch can do. I can't remember how the feedback works in this winc but
there must be a limit.
The bigest problem with the Hitec winch is that it is so slow. That is
probably not important for your boat. Racing is a different story.
Here are some nice pictures and comments on the Atlantis.
http://www.a1-electronics.co.uk/General_Interest/Sailing.shtml
Another ajustable winch if the RMG winch from Australia. Depending on the
exchange rate, the cheapest one is about $125. They are very fast and
strong, but the gears are a little noisy.
I would be interested in anything you have found on decreasing the number of
turns for the Hitec drum winch. 4.5 turns is usually way to much travel for
the 1 meter boats this winch is useful on. I am now using a loop of string
which restricts the transmitter stick travel but would perfer to do it
electronically. I guess the thing to to is add resistors to the transmitter
pot.
Bert
"Rob" <purchasing@fansteelvrwesson.com> wrote in message
news:459cf7f6.0211271052.301bf8a2@posting.google.c om...
> Here's the question, with some options in the solution. This is a
> large sailboat (the Robbe Atlantis) and its genoa (very large
> foresail) is controlled by a dedicated drum-winch servo that has to
> drag a traveller the full length of a 48" (or so) track.
>
> Not having the $150 that Futaba wants for its S5801, I bought a HiTec
> HS725. This winch has more power than the Futaba, but its
> shortcomings include a lack of adjustability and high current draw at
> idle. But for a $100+ savings, I'm willing to mess around to get what
> I need.
>
> So: the drum has a 7 3/8" circumference. To get 48" of sheet travel
> I'm going to need the drum to make at least 6.5 turns. The winch's
> standard rotation is 3.5-4.5 and it depends on the transmitter. I can
> find any number of sites that tell me how to make a standard servo
> into a continuously rotating servo; how to make a 60 degree servo
> into a 90 degree one, or reduce the number of turns on a drumwinch
> servo.
>
> But I can't find a single one that will tell me how to increase the
> number of turns. The options are that I modify the receiver with
> adjustable pot (or pots) in the channel circuit, modify the servo with
> either resistors or pots in the feedback circuit, or throw my hands in
> the air and whine to the wife,"Gimme $150!" Not being fond of black
> eyes, I'll kindly ask you all if you can suggest something..