=20

[FlyRota] Re: Linear Posit= ion=20 Transducer?

Message 35 of 35 =20

From:	Finn = Lassen=20 Add Contact
Sent:	2/2/2004 11:09:26 AM=20=
To:	flyrotary@lancaironline=2Enet
Cc:
Subject:	[Fly= Rotary]=20 Re: Linear Position Transducer?
Attachments:

=20

Actually, giving it another thought, the cheapest and easiest,wou= ld=20 probably be to use the innards of an old mouse=2E
Wrap a spring-loa= ded=20 string (waxed?) several turns around the shaft of one of those small=20= wheels in the mouse=2E Remember the frequency indicators on real old r= adios?=20 (In this case it will be the string moving the axle, not the axle movi= ng=20 the string)=2E

Hook up a scope to the mouse: pin 5 is ground=2E= Pin 2=20 or 3 is output, and one of the other pins supply the power=2E
Exami= ne the=20 output=2E
Your circuit will have to be designed to remember the las= t=20 position before power-down, or you can simply move the manifold to an=20= end-stop and reset the position counter=2E

Finn

Finn Las= sen=20 wrote:

Hi=20 Ed,

This is off-the-wall, but what is used in the $20 electro= nic=20 dial calibers? Maybe it's possible to pick up the signals to the LCD=20= segements=2E=2E=2E I told you it was off the wall=2E

Now, you= can make=20 your own:
Need a strip of binary tape: one strip is black 1/2 the=20= length white the rest, the second stripe is black-white-black-white,= the=20 third twice as many black-whites, etc=2E down to the resolution you = want=2E=20 Then a number of led/photo-transistors pickups that can read the=20 stripes=2E

The easier way is of course just one stripe and y= our=20 circuit just counts the changes as the stripe passes through the=20 led/photo-transistors reader - but requires the circuit remembers th= e=20 current position=2E Also some way to determine direction=2E

T= ake=20 apart an old mouse and see how that works=2E

There must be 10= 's of=20 ways to do this=2E

Finn

Ed Anderson wrote:

Hi Guys,

I am finishing= up the=20 design and fabrication of my variable length EDDIE intake and need=20= some assistance=2E I want to use a voltmeter (or LEDs) to in= dicate=20 the postion of the manifold=2E The simplist approach would a= ppear=20 to have a linear resistor attached such that its arm is moved as t= he=20 manifold moves thereby changing the resistance indicating=20 distance=2E

I've done a lot of Web surfing an= d found=20 a number of linear postion potentiometers=2E The problem is = they=20 cost more than I have invested in the manifold=2E Regular au= dio=20 linear potentiometers do not have the mechanical range I need=2E&n= bsp; I=20 need a position indictor that has at least 5 1/2 - 6" of travel=2E= =20 Anyone have any ideal where something reasonably priced might be=20= found=2E

If you know of a retail cat= alog=20 that have such things I'd appreciate a pointer=2E I can find=20= plenty of Linear Postion Potentiometers - but they cost in the=20 hunderds of $$=2E Need something much cheaper=2E

I know I could devise a 3:1 lever= ratio=20 or some such thing and use one of the cheap (but mechanically rang= e=20 restricted) linear potentiometers for audio circuits, but would ra= ther=20 not=2E
=20

Thanks

Ed Anderson
RV-6A N494BW Rotar= y=20 Powered
Matthews,=20 NC