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Electronics => Electronics => Topic started by: cata on October 14, 2010, 06:48:16 AM

Title: potintometer
Post by: cata on October 14, 2010, 06:48:16 AM

I search after a very large scale potintiometer

Title: Re: DC angle control
Post by: billhowl on October 14, 2010, 08:49:08 AM

I don't know of any other potentiometer that combines continuous rotation and negligable dead band, avaialbe from standard sources like Digikey and Mouser. It is a specialized item and can cost $$$.
You can use this Melexis MLX90316 (http://www.melexis.com/ProdMain.aspx?nID=566 (http://www.melexis.com/ProdMain.aspx?nID=566)), which is carried by DigiKey.

Quote

The MLX90316 is a CMOS Hall sensor that gives the angular position of a magnetic field parallel to the IC surface with an SPI interface. It is designed for contactless rotary position sensors that are frequently required in both automotive and industrial applications. The MLX90316 detects the absolute angular position of a small magnet (diametrally magnetized) that is positioned and rotates above the device surface. By default, the output transfer characteristic is programmed to get a 10%Vdd ... 90%Vdd analog output swing for 0 … 360 Degrees travel (complete revolution).

http://www.melexis.com/Assets/EVB90316_Datasheet_5323.aspx (http://www.melexis.com/Assets/EVB90316_Datasheet_5323.aspx)
http://search.digikey.com/scripts/DkSearch/dksus.dll?lang=en&site=US&WT.z_homepage_link=hp_go_button&KeyWords=MLX90316&x=33&y=19 (http://search.digikey.com/scripts/DkSearch/dksus.dll?lang=en&site=US&WT.z_homepage_link=hp_go_button&KeyWords=MLX90316&x=33&y=19)
http://www.melexis.com/prodfiles/0005323_MLX90316_EVB-DMB_Rev01.pdf (http://www.melexis.com/prodfiles/0005323_MLX90316_EVB-DMB_Rev01.pdf)

http://interface.khm.de/index.php/lab/experiments/rotary-positionsensor-mlx90316/ (http://interface.khm.de/index.php/lab/experiments/rotary-positionsensor-mlx90316/)

Title: Re: DC angle control
Post by: Soeren on October 14, 2010, 02:00:47 PM

Hi,

Quote from: cata on October 14, 2010, 06:48:16 AM

Hi, I search a rotational potentiometer to connect it in a DC motor for know the angle (I purposely don't want a servo)
Does anyone know if there are a potentiometer without limitation ?
I see a lot of potentiometer that have until 10 rotation limitation but my question is if there are exist a non rotation potentiometer limitation ?

They do exist (there's two on the table right in front of me), but they're usually only made for special uses, so they're not exactly cheap.

Regular potentiometers can be found which can be modified if you're handy, but all potentiometer based encoders will go from a few Ohm to max. and then repeat of course.

Then there's angular encoders of various construction, switches, gated infrared light, hall based etc. For the critical stuff, some people still use resolvers (devices that outputs a sine and a cosine signal).

If you tell us what it's for, the needed precision, estimated lifetime etc. and your budget, I'm sure a  solution can be found.