Rotary encoder

Paul Burke · Dec 20, 2005

Pete wrote:

You're probably right. There is a fairly small incorporated assembly
for under 5 pounds from Agilent. It's important for me to get the
component cost right down which doesn't always give the easy solution.

It all depends on how many pulses-per-rev you need. If it's not many,
and you can house a big encoder, you can drill holes in a disk and make
a simple PCB to take a pair of suitably- positioned slotted
optocouplers. But if it's got to be small and high resolution, buy it
in, you'll spend years developing the optics (that's what the encoder
manufacturers did anyway).

Paul Burke

Dec 20, 2005

John Fields wrote:

On 19 Dec 2005 23:17:40 -0800, bill.sloman@ieee.org wrote:

zwsdotcom@gmail.com wrote:
bill.sloman@ieee.org wrote:

Perhaps you might like to reprogram the relevant bit of your brain? You

You're assuming it's flash.

I've seen John Field's brain in action here before. There's nothing
flash about it.

---
Is that supposed to be a slur of some kind?

No. It was just a pun. In at least one of my dialects "flash" means
much the same as "flashy", with a similar sort of implication to
"scintillating", though slightly less positive - "flashy" and "flash"
suggest more superficial brilliance, without real depth.

John Woodgate could probably give chapter and verse, if he were around.

--------------------
Bill Sloman, Nijmegen

Dec 20, 2005

John Fields wrote:

On 19 Dec 2005 17:06:25 -0800, bill.sloman@ieee.org wrote:

John Fields wrote:
On Mon, 19 Dec 2005 22:20:57 GMT, no-one@dont-mail-me.com (Robert
Scott) wrote:

On 19 Dec 2005 12:07:30 -0800, "Pete" <designelect@aol.com> wrote:

Hi,

I need to make a rotary encoder which fits onto a motor shaft from
which I will read the amount of movement in both directions.

The way I want to do this is by using a mechanism similar to that found
in a ball mouse where a slotted wheel interrupts the light to a pair of
sensors.

I've taken apart a couple of mice but can't find any markings on these
devices (phototransistors). If anyone could point me in the right
direction for a manufacturer, I would be very grateful.

Before you re-invent the rotary encoder, look around for an
off-the-shelf solution. There are many many forms of rotary encoder
packages. They come in a wide range of resolutions. Most of them
have their own shaft which you would have to couple to your motor
shaft. However there are also the "hollow shaft" type that can be
fitted onto an existing shaft. In searching, use the term
"incremental encoder".

---
Unfortunately, an incremental encoder won't supply him with the
directional information he needs, so his search term needs to be
"absolute encoder", and he'll also need to specify the resolution he
requires.

The HP incremental encoders - HEDS-9100 and up - in the Farnell
catalogue all come with either two or three channels - the two channels
are two incremental outputs in quadrature, from which any competent
enigneer can get directional information, and the third channel - when
provided - is an index output.

In fact most of the incremental encoders in the Farnell catalogue
explicitly offer quadrature outputs, and I suspect the rest do too,
even if Farnell's copy-writers haven't bothered to mention it

Perhaps you might like to reprogram the relevant bit of your brain? You
seem to have posted one of those bits of information "that ain't so".

---
Yup. Don't know what I was thinking. Incremental with quadrature
outputs is certainly what he's looking for. Just like a ball mouse.

Thanks for the correction.

My pleasure. I know you would be equally happy to field my drop-offs.

----------------
Bill Sloman, Nijmegen

Dec 20, 2005

Paul Burke wrote:

Pete wrote:
You're probably right. There is a fairly small incorporated assembly
for under 5 pounds from Agilent. It's important for me to get the
component cost right down which doesn't always give the easy solution.

It all depends on how many pulses-per-rev you need. If it's not many,
and you can house a big encoder, you can drill holes in a disk and make
a simple PCB to take a pair of suitably- positioned slotted
optocouplers. But if it's got to be small and high resolution, buy it
in, you'll spend years developing the optics (that's what the encoder
manufacturers did anyway).

All the fancy stuff is in the code wheel and the Moire mask you stick
between your LED light source and your two photodetectors,

The Moire mask must have its bars reasonably close to parallel to the
bars on the encoding disk, and it makes life easier if the
printed/etched bars on the surface of the encoding disk are on the side
facing the Moire disk (and vice versa) and the two surfaces are closer
together than the bar spacing.

Parallel bars are a must, but you can live with biggish gaps between
the rotor and the stator if you use a well collimated source, so you
don't get too much penumbra around the shadows of the bars when they
fall on the analysing mask (or vice versa).

Sub-micron encoders apparently use fancier diffraction effects, but the
OP isn't interested in this sort of stuff.

In one system I did, we just left about an inch of lead on the legs of
the LED and the photo-diodes, and bent the leads with pliers after
assembly to get the LED and the two photodiodes in the right places to
interrogate the encoding disk through mask. Worked fine, and never gave
us any trouble.

-----------------
Bill Sloman, Nijmegen

Spehro Pefhany · Dec 20, 2005

On 20 Dec 2005 14:53:12 -0800, the renowned bill.sloman@ieee.org
wrote:

John Fields wrote:
On 19 Dec 2005 23:17:40 -0800, bill.sloman@ieee.org wrote:

zwsdotcom@gmail.com wrote:
bill.sloman@ieee.org wrote:

Perhaps you might like to reprogram the relevant bit of your brain? You

You're assuming it's flash.

I've seen John Field's brain in action here before. There's nothing
flash about it.

---
Is that supposed to be a slur of some kind?

No. It was just a pun. In at least one of my dialects "flash" means
much the same as "flashy", with a similar sort of implication to
"scintillating", though slightly less positive - "flashy" and "flash"
suggest more superficial brilliance, without real depth.

John Woodgate could probably give chapter and verse, if he were around.

"as flash as a rat with a gold tooth" ?

Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

Rich Grise, but drunk · Dec 21, 2005

On Tue, 20 Dec 2005 18:45:34 -0500, Spehro Pefhany wrote:

On 20 Dec 2005 14:53:12 -0800, the renowned bill.sloman@ieee.org
wrote:

John Fields wrote:
On 19 Dec 2005 23:17:40 -0800, bill.sloman@ieee.org wrote:

zwsdotcom@gmail.com wrote:
bill.sloman@ieee.org wrote:

Perhaps you might like to reprogram the relevant bit of your brain? You

You're assuming it's flash.

I've seen John Field's brain in action here before. There's nothing
flash about it.

---
Is that supposed to be a slur of some kind?

No. It was just a pun. In at least one of my dialects "flash" means
much the same as "flashy", with a similar sort of implication to
"scintillating", though slightly less positive - "flashy" and "flash"
suggest more superficial brilliance, without real depth.

John Woodgate could probably give chapter and verse, if he were around.

"as flash as a rat with a gold tooth" ?

Is it true that crematoria capture the gold and such from dental fillings?

Thanks,
Rich

John Fields · Dec 21, 2005

On 20 Dec 2005 14:53:12 -0800, bill.sloman@ieee.org wrote:

John Fields wrote:
On 19 Dec 2005 23:17:40 -0800, bill.sloman@ieee.org wrote:

zwsdotcom@gmail.com wrote:
bill.sloman@ieee.org wrote:

Perhaps you might like to reprogram the relevant bit of your brain? You

You're assuming it's flash.

I've seen John Field's brain in action here before. There's nothing
flash about it.

---
Is that supposed to be a slur of some kind?

No. It was just a pun. In at least one of my dialects "flash" means
much the same as "flashy", with a similar sort of implication to
"scintillating", though slightly less positive - "flashy" and "flash"
suggest more superficial brilliance, without real depth.

---
That's very kind; thank you, sir!

---

John Woodgate could probably give chapter and verse, if he were around.

---
And, no doubt, would...

--
John Fields
Professional Circuit Designer

theJackal · Dec 21, 2005

On 19 Dec 2005 23:17:40 -0800, bill.sloman@ieee.org wrote:

zwsdotcom@gmail.com wrote:
bill.sloman@ieee.org wrote:

Perhaps you might like to reprogram the relevant bit of your brain? You

You're assuming it's flash.

I've seen John Field's brain in action here before. There's nothing
flash about it.

-------------------
Bill Sloman, Nijmegen

Kind way of saying he's an imbecile you mean.

theJackal

Jim Thompson · Dec 21, 2005

On Wed, 21 Dec 2005 18:41:11 +0100, theJackal
<f_a_s_t_g_s_f_r_i_d_e_r@hotmail.com> wrote:

On 19 Dec 2005 23:17:40 -0800, bill.sloman@ieee.org wrote:

zwsdotcom@gmail.com wrote:
bill.sloman@ieee.org wrote:

Perhaps you might like to reprogram the relevant bit of your brain? You

You're assuming it's flash.

I've seen John Field's brain in action here before. There's nothing
flash about it.

-------------------
Bill Sloman, Nijmegen

Kind way of saying he's an imbecile you mean.

theJackal

480)460-2350 | |
| E-mail Address at Website Fax

John Fields · Dec 21, 2005

On Wed, 21 Dec 2005 18:41:11 +0100, theJackal
<f_a_s_t_g_s_f_r_i_d_e_r@hotmail.com> wrote:

On 19 Dec 2005 23:17:40 -0800, bill.sloman@ieee.org wrote:

zwsdotcom@gmail.com wrote:
bill.sloman@ieee.org wrote:

Perhaps you might like to reprogram the relevant bit of your brain? You

You're assuming it's flash.

I've seen John Field's brain in action here before. There's nothing
flash about it.

-------------------
Bill Sloman, Nijmegen

Kind way of saying he's an imbecile you mean.

---
It's really a shame that you don't have the skills required to
follow a thread without tripping yourself up and making it clear
what a buffoon you are. Had you been capable of following the
thread you might have learned that Mr. Sloman was kind enough to
have cleared up what he meant a post or so back.

--
John Fields
Professional Circuit Designer

theJackal · Dec 21, 2005

To the lover of excretory products John Field
Idiot just shut up ...
just go and play in the traffic. I'm sure many (especially members of
your family )can't wait to see you in your grave

"Go easy on your drugs ... you wannabe engineer"

theJackal

Frank Bemelman · Dec 21, 2005

"theJackal" <f_a_s_t_g_s_f_r_i_d_e_r@hotmail.com> schreef in bericht
news:ttjjq1p58fga8qgfqo8rv5o9rdfa5to61o@4ax.com...

To the lover of excretory products John Field
Idiot just shut up ...
just go and play in the traffic. I'm sure many (especially members of
your family )can't wait to see you in your grave

"Go easy on your drugs ... you wannabe engineer"

theJackal

PLONK!

--
Thanks, Frank.
(remove 'q' and '.invalid' when replying by email)

John Fields · Dec 21, 2005

On Wed, 21 Dec 2005 23:00:09 +0100, theJackal
<f_a_s_t_g_s_f_r_i_d_e_r@hotmail.com> wrote:

To the lover of excretory products John Field
Idiot just shut up ...
just go and play in the traffic. I'm sure many (especially members of
your family )can't wait to see you in your grave

"Go easy on your drugs ... you wannabe engineer"

---
It's "John Fields", cretin.

If you can't even get the name right, why do you think that your
opinion matters? It doesn't. You're just another ignorant poser
pretending to knowledge which you don't have for the sake of having
us consider you one of us. You're not. Just take a look at your
miserable performance on the fantastically funny flip-flop thread
and it should be obvious, even to you, that you're a loser.

If you need any more proof, read the seven amp LED thread again.

--
John Fields
Professional Circuit Designer

Rich Grise · Dec 21, 2005

On Wed, 21 Dec 2005 16:52:05 -0600, John Fields wrote:

On Wed, 21 Dec 2005 23:00:09 +0100, theJackal
f_a_s_t_g_s_f_r_i_d_e_r@hotmail.com> wrote:

To the lover of excretory products John Field
Idiot just shut up ...
just go and play in the traffic. I'm sure many (especially members of
your family )can't wait to see you in your grave

"Go easy on your drugs ... you wannabe engineer"

---
It's "John Fields", cretin.

If you can't even get the name right, why do you think that your
opinion matters? It doesn't. You're just another ignorant poser
pretending to knowledge which you don't have for the sake of having
us consider you one of us. You're not. Just take a look at your
miserable performance on the fantastically funny flip-flop thread
and it should be obvious, even to you, that you're a loser.

If you need any more proof, read the seven amp LED thread again.

John, are you really so lonely and desperate that you take amusement
at baiting these trolls?

Thanks,
Rich

John Fields · Dec 22, 2005

On Wed, 21 Dec 2005 23:37:21 GMT, Rich Grise
<eatmyshorts@doubleclick.net> wrote:

John, are you really so lonely and desperate that you take amusement
at baiting these trolls?

---
Nope.

--
John Fields
Professional Circuit Designer

Dec 22, 2005

Jim Thompson wrote:

On Wed, 21 Dec 2005 18:41:11 +0100, theJackal
f_a_s_t_g_s_f_r_i_d_e_r@hotmail.com> wrote:

On 19 Dec 2005 23:17:40 -0800, bill.sloman@ieee.org wrote:

zwsdotcom@gmail.com wrote:
bill.sloman@ieee.org wrote:

Perhaps you might like to reprogram the relevant bit of your brain? You

You're assuming it's flash.

I've seen John Field's brain in action here before. There's nothing
flash about it.

-------------------
Bill Sloman, Nijmegen

Kind way of saying he's an imbecile you mean.

theJackal

Sloman is the imbecile, AND an unemployed BUM on welfare.

I guess I really must be an imbecile. I keep on hoping that I'll get
one of these jobs I keep on applying for. despite the evidence of
experience - one job interview last year, and two this year. Of course,
if Philips had gone ahead with that ultrasound project, I'd be working
now.

Maybe I should become a paranoid imbecile, and blame it all on a
capitalist conspiracy organised by Jim Thompson, but my sense of humour
kicks in as soon as I try and see Jim as any kind of Master Mind.

And for students of language - "Bill" in Dutch is buttock, so over here
I really am a bum.
Technically it is "bil" rather than "bill", and the plural "billen" -
buttocks - is the high frequency form but the pun still works. Jim
doesn't exactly score points for originality.

-------------------
Bill Sloman, Nijmegen

----------------
Bill Sloman, Nijmegen

Richard the Dreaded Liber · Dec 22, 2005

On Thu, 22 Dec 2005 02:18:04 -0800, bill.sloman wrote:

Maybe I should become a paranoid imbecile, and blame it all on a
capitalist conspiracy organised by Jim Thompson, but my sense of humour
kicks in as soon as I try and see Jim as any kind of Master Mind.

LOL!
<AOL>
Me, Too!
</AOL>

Cheers!
Rich

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