[simpits-tech] Switchs, Rotary and pot

[Marv De Beque]

No.

A pot (short for potentiometer) is a device that rotates over a given
portion of a circle.  This is usually about 270 degrees, but there are
multi-turn pots that rotate 5, 10, or 20 turns from lock to lock.

A pot is nothing more than a resistor that can be changed from zero
(usually) to its maximum value.  100,000 Ohms is typical for simulator use.

A pot, theoretically, has an infinite adjustment between its two extreme
values (i.e., 0 to 100,000 Ohms).  So, like a faucet (in good working
order), you can adjust the flow to any value in between.

A rotary encoder is different.  It is a device that rotates like a pot, but
instead of acting like a variable resistor, it sends out a set of pulses as
the knob turns.  It is sort of like putting playing cards on the forks of a
bicycle and turning the wheel.  As each spoke passes, an audible click is
heard (a pulse).  You can count the pulses and then determine how far the
wheel has rotated.  You need two two playing cards slightly offset in an
angular fashion to tell which direction the wheel is rotating.  By looking
at which card clicks first you can tell direction of spin.

The thing about encoders is that they have a "granularity".  Unlike a pot
which is infinite, there are finite steps to an encoder.  There may be any
number of steps you can get from a few to several hundred steps per
revolution.  You can resolve the rotation only down to the step, but you can
not tell how much an encoder rotates between step steps (i.e., a half step).

Most encoders do not remember their positions when power to the system is
turned off.  So, the system must somehow save the last known position if it
is to pick up where it left off at power down.  A pot has the same
resistance whether the system has power or not.

A pot almost always has a mechanical stop.  Resistance can only go so far.
An encoder does not necessarily have a mechanical stop and can be rotated
continuously without stopping.

An example of an encoder is a computer mouse (at least the old ones).  Some
new car stereos have them too.

Two different animals that can be used in similar ways and each has its
advantages.

Sorry for the long message, but I am short on time.

Marv
-- 


> From: "Frank Riedel" <frank@rezultat.dk>
> Reply-To: simpits-tech@simpits.org
> Date: Mon, 5 Aug 2002 23:35:45 +0200
> To: <simpits-tech@simpits.org>
> Subject: Re: [simpits-tech] Switchs, Rotary and pot
> 
> Thanks alot for the explanation ;o)
> 
> I found the F16 panels at simpits.org...
> 
> Did i get it right - rotary encoders = potentiometers ??
> 
> Thanks
> Frank !
> 
> ----- Original Message -----
> From: "Andreas Fransson" <andreas.fransson@post.utfors.se>
> To: <simpits-tech@simpits.org>
> Sent: Monday, August 05, 2002 9:09 PM
> Subject: Re: [simpits-tech] Switchs, Rotary and pot
> 
> 
>> Frank,
>> 
>> 3-way switches are (usually) on-off-on. With or without automatic return
> to
>> center position (not sure what the english expression for this would be).
>> 
>> Rotaries, if you mean rotary switches and not rotary encoders, may or may
>> not have limits. A couple I have here for example do not. They go all the
>> way around. What they do is just rotate a common ground around a number of
>> connections. Like a "normal" switch but with many more positions. Mine
> have
>> 12 I think. You could say that they are "all-on" in the sense that one
> lead
>> is always active. Encoders are a different breed altogether. They are
>> commonly used to sense motion (rotation) rather than indicate switch
>> positions.
>> 
>> "Pots", or potentiometers, are basically variable resistors. I you use one
>> with EPIC, or as a replacement for a joystick pot, it is 100 ohm linear
> pots
>> you want.
>> 
>> If you use the EPIC, the kind of switches you use are almost unimportant.
>> EPL (the EPIC programming language) is very flexible. It's not at all like
>> the standard joystick momentary on/off pushbuttons.
>> 
>> What aircraft (or whatever) panels are you looking for?
>> 
>> Andreas
>> http://valhallainc.d2g.com
>> 
>> 
>> From: "Frank Riedel" <frank@rezultat.dk>
>>> Hi All !
>>> 
>>> 3 way switchs - is that off-on-off  or ????
>>> Rotary - is that 360 dg. or ???
>>> 2 way switchs - is that on-on  or ???
>>> Pot - is that a normal potmeter 100 ohm or  ???
>>> Is EPIC control all those switchs nomatter if it is on-of or on-on ???
>>> 
>>> Do anyone of you guys have a link to a page where i can read about it
> ???
>>> 
>>> and do anyone have a set of drawings of panels without knobs on ????
>>> 
>>> thanks for all your help... i'm on the road for my first real pit ;o)
>>> 
>>> Frank
>> 
>> 
>> 
>> _______________________________________________
>> Simpits-tech mailing list
>> Simpits-tech@simpits.org
>> http://www.simpits.org/mailman/listinfo/simpits-tech
>> To unsubscribe, please see the instructions at the bottom of the above
> page.  Thanks!
> 
> 
> _______________________________________________
> Simpits-tech mailing list
> Simpits-tech@simpits.org
> http://www.simpits.org/mailman/listinfo/simpits-tech
> To unsubscribe, please see the instructions at the bottom of the above page.
> Thanks!