How to increase the n° of turns of a servo ?

HI everybody,
I finally did’ it ! EURECA !!!

Used an old analog Servo winch HS-725 BB.
Minimum revolution 540° and (actual *) maximum 2350° with Tx Ranger III Sky - (including trim escursion)
Gears ratio 44T / 30T = 1.46
External potentiometer 10 turns - 5 Kohm

  • Revolution degrees is fonction of the gears ratio.
    To avoid loosing torque, the pulley is mounted on the servo axis.
    This set-up is developped for a vintage model, where the main boom requires some 85cm (33.5 ") sheet lenght.
    This is my prototype and weight 179 g. (servo only 110 g.)

Obviously the warranty of HiTec is lost - my servo was 5 years old …

The small axis protrusion from the pulley will be used as pulley support to avoid cantilever effort on the servo axis (old potentiometer actually disconnected)


Se Bon!

I like the way you mounted the board to the top of the case. How do you attach the gear and pulley to the shaft on the servo?

with a “Servo hub HITEC” available at as well gears and other stuff while the pot was bought in France, but Bourns is also very good.
The added shaft on top of the pulley I made it myself on my small lathe.

Here some more pics

Bonjour Claudio,

As always, very nice.

Now we just need to get you excited about building a Footy…:wink:


ps: how is the M coming?

HI Bill,
the M is going very well. I have too big hands for a Footy.
Actually I’ m preparing the construction of a 15mJI. The original, Tuiga, will celebrate the 100th anniversary in 2009. This is why I was developping the multi -turns winch.
I just finish the assembly of the last design by taking care about the cantilever of the pulley. provided me the material.
The sides are plywood 1.5mm and carbon fiber 2x190g/m².
Gears ratio 58/30 - 7 turns without trim - sheet lenght 88 cm in 9.5 seconds // 8.5 turns with full trim - sheet lenght 101 cm in 10.5.
Further I drew a new M hull very special that I will presents soon.