Throttle Construction

[Guest]

Hi GuysJust wrapping up on my 727 throttle design, But I need to make a decision on the pots I should use before I can finalize it.I want to have as smooth of control as possible, to be able to make precision adjustments, Im a toolmaker and mechanical designer by trade and the the mechanical end of the throttle is first class.Im curious to know if there is anything better to use then 100k pots(maybe 10-turn pots?)thx in advanceFloyd Stollewww.stollco.com

[Guest MikePowell]

Floyd,There is some background material on potentiometers here http://www.mikesflightdeck.com/potentiometers.htm that may be of interest to you. Not mentioned there is something called a "resistive position sensor". It's a spring loaded drum that rotates a multi-turn pot. A string, steel tape or some other flexible line is wound on the drum. Pulling it rotates the pot. Releasing tention on it allows the spring to wind it back onto the drum and restore the pot to its start position. With a quality pot, it is very linear and offers precise position location.A mechanism similar to this might be useful on your throttle quadrant. Appropriate selection of the drum radius will determine have many turns on your pot occur as the throttle is moved through its full range.Resistive position sensors are available from a variety of sources, but are rather pricey. However, after taking a look at your web site, I rather doubt you would have any trouble at all making your own.Mikewww.mikesflightdeck.comInfo for simpit builders

[Guest]

Thanks for the info MikeI think I'll go with a bourns 91 series.>conductive plastic element<>100,000 cycles life

[Guest MikePowell]

Sounds good, Floyd. One additional thing you might want to check is the pot's actual linearity at the extreme ends of its rotation. Depending upon its construction, a pot typically displays significant non-linearity in those two regions. This is the area that the connections between the resistive element and the metal terminals are made. Some pots can lose 40% of their linear range due to this. The Bourns unit is probably better made than this, but you might want to actually check the pot before you commit to a gear ratio.Mikewww.mikesflightdeck.comInfo for simpit builders.