# What is this type of dial/knob called?

K

#### Kruminilius W.

Jan 1, 1970
0
I'm trying to find the type of dial that you can turn in one direction or
the other without it stopping (unlike a potentiometer). I have no idea what
this part is called. Any thoughts?

Thanks.

A

#### Andrew Holme

Jan 1, 1970
0
Kruminilius said:
I'm trying to find the type of dial that you can turn in one direction or
the other without it stopping (unlike a potentiometer). I have no idea what
this part is called. Any thoughts?

Thanks.

Do you mean an optical shaft encoder?

K

#### Kruminilius W.

Jan 1, 1970
0
I think the optical shaft encoder would do what I want, but they appear to
be fairly expensive. The device I'm thinking of probably generates some
type of current when the knob is turned, where the current is proportional
to the rotation speed. I imagine that they're pretty cheap since I've seen
them on a variety of cheap electronic devices such as the volume/digial

J

#### John Popelish

Jan 1, 1970
0
Kruminilius said:
I think the optical shaft encoder would do what I want, but they appear to
be fairly expensive. The device I'm thinking of probably generates some
type of current when the knob is turned, where the current is proportional
to the rotation speed. I imagine that they're pretty cheap since I've seen
them on a variety of cheap electronic devices such as the volume/digial

Anything digital generates pulses, (counts) not voltage. Here is an
example of a low cost encoder used as a manual digital pulse source
available from Digikey:
http://www.grayhill.com/Grayhill.ns...753570fa03f86256846007456b2/$FILE/E-33-34.pdf M #### Matthias Melcher Jan 1, 1970 0 What you are looking for is a rotational encoder, or gray code encoder. There are some low cost ($3 to $6) ones out there but some of them really suck (they ar not sturdy, go clack clack clack, and lose contact after a while). Optical encoders are much nicer, but incredibly expensive.$125 and
up. You can get those even with an RS232 interface that returns relative (I
moved 20 degrees) or absolute values (I am at 24 degrees).

see:

http://www.digikey.com/scripts/DkSearch/dksus.dll?Criteria?Ref=56293&Site=US&Cat=33096389

Low end:
http://rocky.digikey.com/WebLib/Bourns/Web Data/ECW1J Series.pdf

High end:
http://rocky.digikey.com/WebLib/CUI Inc/Web data/MEH30-XXXXP-XX-XX-XX.pdf

J

#### John Popelish

Jan 1, 1970
0
Matthias said:
What you are looking for is a rotational encoder, or gray code encoder.
There are some low cost ($3 to$6) ones out there but some of them really
suck (they ar not sturdy, go clack clack clack, and lose contact after a
while). Optical encoders are much nicer, but incredibly expensive. $125 and up. (snip) The optical encoders are more expensive than the contact types, but there are some inexpensive ones available from Digikey.$20.55
http://www.grayhill.com/Grayhill.ns...b22369d0aa786256846007185ff/$FILE/E-15-16.pdf$33.20
http://www.grayhill.com/Grayhill.ns...18d91ce4aba862568970060a1e5/$FILE/Bltn725.pdf$44.62
http://www.grayhill.com/grayhill.ns...9beda758ae78625687b005e3a4b/$FILE/E-19-23.pdf$30.00
http://rocky.digikey.com/WebLib/CUI Inc/Web data/RE20XXXXXXX.pdf
\$51.37
http://www.bourns.com/pdf/enc1j.pdf

W

#### william coleman

Jan 1, 1970
0
Kruminilius said:
I'm trying to find the type of dial that you can turn in one direction or
the other without it stopping (unlike a potentiometer). I have no idea what
this part is called. Any thoughts?

Thanks.
It is called a pot without stops

A

Jan 1, 1970
0
Kruminilius W. said:
I think the optical shaft encoder would do what I want, but they appear to
be fairly expensive. ....................
The device I'm thinking of probably generates some
type of current when the knob is turned, where the current is proportional
to the rotation speed. .......................
I imagine that they're pretty cheap since I've seen
them on a variety of cheap electronic devices such as the volume/digial

50 cent electric gear motor with a knob on the end?

Al...

C

#### colin

Jan 1, 1970
0
william coleman said:
It is called a pot without stops

or a knob with a loose grub screw, i like the cheap 50cent dc motor idea
best

Colin =^.^=

M

#### me

Jan 1, 1970
0
I'm trying to find the type of dial that you can turn in one direction
or the other without it stopping (unlike a potentiometer). I have no
idea what this part is called. Any thoughts?

Thanks.

There are optical shaft encoders, or cheaper mechanical encoders like are
used to adjust the display on some computer monitors. There are variable
capacitors. Also popular is the metal shaft with a knob on it, which moves
a dial string.

What exactly are you wanting to use this dial you are looking for for...

B

#### Ben Stephens

Jan 1, 1970
0
Kruminilius said:
I'm trying to find the type of dial that you can turn in one direction or
the other without it stopping (unlike a potentiometer). I have no idea what
this part is called. Any thoughts?

Thanks.
What about those wheels in a balled computer mouse??? they do what you
want to do, but they are fragile.

K

#### Kitchen Man

Jan 1, 1970
0
It is called a pot without stops

I don't think so. The poster appears to be looking for a device that
indicates relative rotation, not absolute position. His example is of
a digital volume knob on an inexpensive stereo. He's got some good
answers on that - most intriguing to me is the electric motor
(generator, actually, since mechanical motion is producing current)
idea. I think using one of the cheaper optical encoders is probably
the simplest implementation.

K

#### Kitchen Man

Jan 1, 1970
0
What about those wheels in a balled computer mouse??? they do what you
want to do, but they are fragile.

Yep. Those are the optical encoders that have been discussed. I
think the OP wants a more rugged human interface - something to be
moved with the fingers?

J

#### John Fields

Jan 1, 1970
0
The poster appears to be looking for a device that
indicates relative rotation, not absolute position. His example is of
a digital volume knob on an inexpensive stereo. He's got some good
answers on that - most intriguing to me is the electric motor
(generator, actually, since mechanical motion is producing current)
idea.

J

Jan 1, 1970
0

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