Digital Knob?

Floyd · Guest

I need a control knob that will emit pulses as it is turned. Would need to be two lines I suppose--one line for left the other for right. I don't want to use a potentiometer and an ADC since some positions would not settle on a specific value. I know something like this must exist, but after searching I can't find one.

Any ideas of the type of device I'm looking for? Keywords?
Thanks

kypec · Joined: 20 Sep 2003 Posts: 54

Try something like rotary+quadrature+encoder
Companies ALPS & Bourns are producing such encoders.

Humberto · Posted: Thu Nov 10, 2005 6:52 am

Go to:

http://www.digikey.com

and search for: GH3071-ND
will show you the model 25LB10-Q ENCODER MECHANICAL 36POS made by Grayhill Inc.

Humberto

sseidman · Joined: 14 Mar 2005 Posts: 159

You'll find mechanical and optical encoders of this type. Mechanical may bounce, and thus might need some processing on the input.

Also, they come in types that detent (i.e., you'll feel the clicks), and types that turn smoothly.

rnielsen · Joined: 23 Sep 2003 Posts: 852 Location: Utah

There are encoders that simply put out a quadrature signal (two pulses where one goes up first followed by the other which will tell you which way the encoder is turning). This type should also have a 'home' pulse so you know where you are. Unfortunately, you have to rotate around until you hit this 'mark' before you know just where you are. You would need to find this mark everytime you turned power on.

There are also Absolute encoders. This is a sort of parallel output encoder where you can know exactly which position the encoder is in even when power has just been powered up. It uses a binary type of output that counts up or down like you would in binary.

Ronald

kender · Joined: 09 Aug 2004 Posts: 768 Location: Silicon Valley

Take a look at Bourns 3315 mechanical encoder. It's available from DigiKey. The debouncing circuit schematic in the datasheet too.