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Now, that's what I like about this group.
Aways someone with a brilliantly simple solution to my complex
problems.
Thanks Bill. That just might be
ticket!
Ed Anderson
RV-6A N494BW Rotary Powered
Matthews, NC
----- Original Message -----
Sent: Monday, February 02, 2004 3:20
PM
Subject: [FlyRotary] Re: Linear Position
Transducer?
Why not a simple (regular rotational) potentiometer. Put a disk on the
shaft that is the circumference of the max travel that you need, wrap a string
around the disk, attached at each end to the manifold parts, and then movement
of the manifold will cause the shaft of the pot to rotate, and the
rotation will be constrained to less than 1 revolution.
Bill Schertz
| [FlyRota] Re: Linear Position
Transducer? |
Message 35 of 35
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Actually, giving it another thought, the cheapest and easiest,would
probably be to use the innards of an old mouse. Wrap a spring-loaded
string (waxed?) several turns around the shaft of one of those small
wheels in the mouse. Remember the frequency indicators on real old
radios? (In this case it will be the string moving the axle, not the
axle moving the string). Hook up a scope to the mouse: pin 5 is
ground. Pin 2 or 3 is output, and one of the other pins supply the
power. Examine the output. Your circuit will have to be designed
to remember the last position before power-down, or you can simply move
the manifold to an end-stop and reset the position
counter. Finn Finn Lassen wrote:
Hi
Ed,
This is off-the-wall, but what is used in the $20
electronic dial calibers? Maybe it's possible to pick up the signals
to the LCD segements... I told you it was off the wall.
Now,
you can make your own:
Need a strip of binary tape: one strip is
black 1/2 the length white the rest, the second stripe is
black-white-black-white, the third twice as many black-whites, etc.
down to the resolution you want. Then a number of
led/photo-transistors pickups that can read the stripes.
The
easier way is of course just one stripe and your circuit just counts
the changes as the stripe passes through the led/photo-transistors
reader - but requires the circuit remembers the current position. Also
some way to determine direction.
Take apart an old mouse and
see how that works.
There must be 10's of ways to do
this.
Finn
Ed Anderson wrote:
Hi Guys,
I am finishing up
the design and fabrication of my variable length EDDIE intake and
need some assistance. I want to use a voltmeter (or LEDs) to
indicate the postion of the manifold. The simplist approach
would appear to have a linear resistor attached such that its arm is
moved as the manifold moves thereby changing the resistance
indicating distance.
I've done a lot of Web surfing and
found a number of linear postion potentiometers. The problem
is they cost more than I have invested in the manifold.
Regular audio linear potentiometers do not have the mechanical range
I need. I need a position indictor that has at least 5 1/2 -
6" of travel. Anyone have any ideal where something reasonably
priced might be found.
If you know of a retail catalog
that have such things I'd appreciate a pointer. I can find
plenty of Linear Postion Potentiometers - but they cost in the
hunderds of $$. Need something much cheaper.
I know I could devise a 3:1 lever ratio
or some such thing and use one of the cheap (but mechanically range
restricted) linear potentiometers for audio circuits, but would
rather not.
Thanks
Ed Anderson
RV-6A N494BW Rotary
Powered
Matthews,
NC |
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