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Infrared emitter and detector pair

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m II

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Feb 14, 2011, 11:16:56 PM2/14/11
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I have a pair of these I'd like to use in a tachometer setup. The
emitter is 13 to 15 mw output. The detector is 20 degrees angle of half
sensitivity.

The problem is that it's really hard to put a cog wheel type interrupter
blade between them.

Is there any possibility of using reflective tape on the flywheel and
placing the emitter/receiver pair parallel and adjacent to each other?

Would there be enough light reflected, say, at 5 or 6 mm to get a useful
measurement?

mike the genuine
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ne...@jecarter.us

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Feb 15, 2011, 10:03:01 AM2/15/11
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On Mon, 14 Feb 2011 21:16:56 -0700, m II <C...@in.the.hat> wrote:

>-----BEGIN PGP SIGNED MESSAGE-----
>Hash: SHA1
>
>I have a pair of these I'd like to use in a tachometer setup. The
>emitter is 13 to 15 mw output. The detector is 20 degrees angle of half
>sensitivity.
>
>The problem is that it's really hard to put a cog wheel type interrupter
>blade between them.
>
>Is there any possibility of using reflective tape on the flywheel and
>placing the emitter/receiver pair parallel and adjacent to each other?
>
>Would there be enough light reflected, say, at 5 or 6 mm to get a useful
>measurement?
>
>
>
>mike the genuine

I have an ancient tachometer (displays RPM on an analog meter ;-) that
uses light from a focused flashlight bulband a relatively fast
detector to measure RPM using reflected light. I use metallic duct
tape (aluminum, not cloth) as the reflective surface if the
shaft/fan/whatever does have sufficient contrast.

I think that same tape would work for IR.

I have a newer laser + photo-diode version for measuring speeds above
10,000RPM. Same principle, just newer technology - and a digital
readout.

John

Herman

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Feb 16, 2011, 6:47:55 AM2/16/11
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"m II" <C...@in.the.hat> wrote in message news:4d59...@news.x-privat.org...

You can't make nothing for 40 bucks.
http://www.harborfreight.com/digital-photo-sensor-tachometer-66632.html


m II

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Feb 16, 2011, 12:44:25 PM2/16/11
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On 11-02-16 04:47 AM, Herman wrote:

> You can't make nothing for 40 bucks.
> http://www.harborfreight.com/digital-photo-sensor-tachometer-66632.html


That would be perfect if all I needed was the rpm. I want to use the rpm
reading to vary a servo, which will move the throttle linkage on a small
generator.

Something similar to this:

http://www.youtube.com/watch?v=v7GLQU-0Nwc

I need to use a reflector instead of a cogged wheel to direct the light
to the phototransistor.

I guess a hall effect setup, with a rotating magnet would be fine, but I
already have the photo detector.

mike


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George Herold

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Feb 16, 2011, 3:23:18 PM2/16/11
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I'm sure you can get the IR source->mirror->photodiode to work. I'm
not sure I'd want to mount it on a IC motor and expect it to stay
aligned with all the vibration.

How 'bout something else... surely there's lots of ways to sense the
RPM of a motor. Can you pick off a signal that does the spark
timing? Maybe a coil wrapped about the spark plug wire?

George H.

whit3rd

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Feb 16, 2011, 5:12:05 PM2/16/11
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On Feb 14, 8:16 pm, m II <C...@in.the.hat> wrote:

> I have a pair of these I'd like to use in a tachometer setup.

> Is there any possibility of using reflective tape on the flywheel and


> placing the emitter/receiver pair parallel and adjacent to each other?

Sure; you can buy an emitter/sensor pair already packaged to
accomplish
that (Sharp GP2S24xxx parts are the first my catalog here mentions).

But, what do you mean 'flywheel'? If this is for an automobile,
there's
no need to do anything exotic, the primary side of the ignition coil
has a large and reliable electrical signal all ready for you.

John Fields

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Feb 16, 2011, 7:13:40 PM2/16/11
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On Wed, 16 Feb 2011 10:44:25 -0700, m II <C...@in.the.hat> wrote:

>-----BEGIN PGP SIGNED MESSAGE-----
>Hash: SHA1
>
>On 11-02-16 04:47 AM, Herman wrote:
>
>> You can't make nothing for 40 bucks.
>> http://www.harborfreight.com/digital-photo-sensor-tachometer-66632.html
>
>
>That would be perfect if all I needed was the rpm. I want to use the rpm
>reading to vary a servo, which will move the throttle linkage on a small
>generator.
>
>Something similar to this:
>
>http://www.youtube.com/watch?v=v7GLQU-0Nwc
>
>I need to use a reflector instead of a cogged wheel to direct the light
>to the phototransistor.
>
>I guess a hall effect setup, with a rotating magnet would be fine, but I
>already have the photo detector.

---
If you can get Fairchild to sample you one of these:

http://www.fairchildsemi.com/ds/QR/QRD1113.pdf

or if you can get one through disty, you'd probably be better off than
trying to cobble something together out of what you have on hand; no
offense intended. :-)

There are also reflective sensors available which exhibit greater
sensitivity by having their emitter and detector angled so that their
axes are collinear when a reflective surface with its plane normal to
their half angle is placed a certain distance away from them, but I'm
off to cook roasted beets, baked chicken thighs, and sliced tomatoes
sprinkled with oregano and drizzled with extra virgin olive oil for
dinner, so I can't help with that search right now. :-(

;)


---
JF

m II

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Feb 16, 2011, 7:46:13 PM2/16/11
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"m II" wrote in message news:4d59...@news.x-privat.org...

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Actually I couldn't care less but wanted to see how many people still
haven't kill filtered me for putting my problems to the public.

Thanks for your responses. It is good to know who your real friends are.

http://groups.google.ca/groups/search?hl=en&as_q=&as_epq=GymyBobism&as_oq=&as_eq=&num=100&scoring=&lr=&as_sitesearch=&as_qdr=&as_drrb=b&as_mind=1&as_minm=1&as_miny=2003&as_maxd=1&as_maxm=1&as_maxy=2008&as_ugroup=&as_usubject=&as_uauthors=m+II&safe=off


mike the genius

m II

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Feb 16, 2011, 8:25:53 PM2/16/11
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On 11-02-16 05:13 PM, John Fields wrote:

> If you can get Fairchild to sample you one of these:
>
> http://www.fairchildsemi.com/ds/QR/QRD1113.pdf
>
> or if you can get one through disty, you'd probably be better off than
> trying to cobble something together out of what you have on hand; no
> offense intended. :-)
>
> There are also reflective sensors available which exhibit greater
> sensitivity by having their emitter and detector angled so that their
> axes are collinear when a reflective surface with its plane normal to
> their half angle is placed a certain distance away from them, but I'm
> off to cook roasted beets, baked chicken thighs, and sliced tomatoes
> sprinkled with oregano and drizzled with extra virgin olive oil for
> dinner, so I can't help with that search right now. :-(


A: I like the angling of the two items to increase the reflected light.
That alone should make this work. I'll find the protractor and the draw
the plane of reflection tonight.

B: Having been a vegetarian for over ten years, I can honestly say your
idea of dinner is revolting. No offense intended.

Who knew they actually had'em?

http://i193.photobucket.com/albums/z265/timmrd/DSC_0009-2-1.jpg

which was found here:

http://tinyurl.com/36a8dw6


mike
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Rich Grise

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Feb 16, 2011, 9:29:01 PM2/16/11
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John Fields wrote:

> sprinkled with oregano and drizzled with extra virgin olive oil for
> dinner, so I can't help with that search right now. :-(

How is "extra virgin" olive oil different from plain ol' ordinary
everyday olive oil, other than the price?

Thanks,
Rich

k...@att.bizzzzzzzzzzzz

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Feb 16, 2011, 9:45:13 PM2/16/11
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On Wed, 16 Feb 2011 18:29:01 -0800, Rich Grise <ri...@example.net.invalid>
wrote:

"Virgin" means that it's olive oil (no chemicals added). "Extra-virgin" means
it's from the "first pressing" of the olives and is supposed to be better.
Neither of these terms have any legal meaning and the meaning words, if not
the oil, are often adulterated.

stra...@yahoo.com

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Feb 17, 2011, 12:08:33 AM2/17/11
to

Those are similar to some Omron opto-reflective sensors I used as the
pedal switching in the pipe organ I built 23 years ago. Those, some
black masking tape and 3M reflector tape worked just fine. 2 sensors
per pedal and I had MIDI velocity.

G²

John Fields

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Feb 17, 2011, 5:32:02 AM2/17/11
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On Wed, 16 Feb 2011 18:29:01 -0800, Rich Grise
<ri...@example.net.invalid> wrote:

---
From:

http://en.wikipedia.org/wiki/Olive_oil#Retail_grades_in_IOC_member_nations

"Extra-virgin olive oil comes from virgin oil production only,
contains no more than 0.8% acidity, and is judged to have a superior
taste. Extra Virgin olive oil accounts for less than 10% of oil in
many producing countries. It is used on salads, added at the table to
soups and stews and for dipping."

---
JF

John Fields

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Feb 17, 2011, 6:02:42 AM2/17/11
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On Wed, 16 Feb 2011 18:25:53 -0700, m II <C...@in.the.hat> wrote:


>B: Having been a vegetarian for over ten years, I can honestly say your
>idea of dinner is revolting. No offense intended.

---
Offense taken.

Plonk.

---
JF

Rich Grise

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Feb 17, 2011, 6:32:57 AM2/17/11
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John Fields wrote:
> On Wed, 16 Feb 2011 18:29:01 -0800, Rich Grise
>>John Fields wrote:
>>
>>> sprinkled with oregano and drizzled with extra virgin olive oil for
>>> dinner, so I can't help with that search right now. :-(
>>
>>How is "extra virgin" olive oil different from plain ol' ordinary
>>everyday olive oil, other than the price?
>>
> From:
>
> http://en.wikipedia.org/wiki/Olive_oil#Retail_grades_in_IOC_member_nations
>
> "Extra-virgin olive oil comes from virgin oil production only,
> contains no more than 0.8% acidity, and is judged to have a superior
> taste. Extra Virgin olive oil accounts for less than 10% of oil in
> many producing countries. It is used on salads, added at the table to
> soups and stews and for dipping."
>
Thanks for this - I fear I've never tasted olive oil, and am kind of
surprised that it has any flavor at all - when I get a salad and ask
for "just some oil and vinegar on the side," what they bring, according
to my taste buds, might as well be Mazola or 10W30. ;-)

Thanks!
Rich

John Fields

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Feb 17, 2011, 7:38:37 AM2/17/11
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On Wed, 16 Feb 2011 12:23:18 -0800 (PST), George Herold
<ghe...@teachspin.com> wrote:


> I'm sure you can get the IR source->mirror->photodiode to work. I'm
>not sure I'd want to mount it on a IC motor and expect it to stay
>aligned with all the vibration.
>
> How 'bout something else... surely there's lots of ways to sense the
>RPM of a motor. Can you pick off a signal that does the spark
>timing? Maybe a coil wrapped about the spark plug wire?
>
>George H.

---
As a capacitive pick-off?

---
JF

George Herold

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Feb 17, 2011, 9:03:27 AM2/17/11
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There ya go... even easier than mucking with the high voltage side....
always a worry that the HV will fry something.

George H.

George Herold

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Feb 17, 2011, 9:11:55 AM2/17/11
to
On Feb 17, 7:38 am, John Fields <jfie...@austininstruments.com> wrote:
> On Wed, 16 Feb 2011 12:23:18 -0800 (PST), George Herold
>
> <gher...@teachspin.com> wrote:
> > I'm sure you can get the IR source->mirror->photodiode to work.  I'm
> >not sure I'd want to mount it on a IC motor and expect it to stay
> >aligned with all the vibration.
>
> > How 'bout something else... surely there's lots of ways to sense the
> >RPM of a motor.  Can you pick off a signal that does the spark
> >timing?  Maybe a coil wrapped about the spark plug wire?
>
> >George H.
>
> ---
> As a capacitive pick-off?
>
> ---
> JF

No, I was thinking about sensing the current in the coil.... But
better to work on the primary side as Whit3rd suggested. Too much
worry about getting 'whacked' by the HV.

George H.

m II

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Feb 17, 2011, 12:05:18 PM2/17/11
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that was a surprise

mike

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John Fields

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Feb 17, 2011, 2:58:18 PM2/17/11
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---
You can't sense the current in a conductor by wrapping a coil of wire
around it.

---
JF

George Herold

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Feb 17, 2011, 10:33:59 PM2/17/11
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> JF- Hide quoted text -
>
> - Show quoted text -

Oh, does it need to be a torriod?
Thanks for the correction.

George H.

Fred Bartoli

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Feb 18, 2011, 4:07:47 AM2/18/11
to
George Herold a �crit :

Yup. Lookup Rogowski coils.

--
Thanks,
Fred.

John Fields

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Feb 18, 2011, 6:48:12 AM2/18/11
to

---
Nope, a toroid. ;)

---
JF

Winston

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Feb 18, 2011, 9:27:02 AM2/18/11
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Fred Bartoli wrote:
> George Herold a écrit :

Or spiral.
http://en.wikipedia.org/wiki/Rogowski_coil

--Winston

Phil Hobbs

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Feb 18, 2011, 10:31:03 AM2/18/11
to

It means that it's green and putrid-tasting. You have to add balsamic
vinegar to cut the taste, and then put it over bad-tasting 'baby greens'
to make a modern salad. Ain't progress wonderful. :(

Cheers

Phil "plain lettuce forever" Hobbs


--
Dr Philip C D Hobbs
Principal
ElectroOptical Innovations
55 Orchard Rd
Briarcliff Manor NY 10510
845-480-2058

email: hobbs (atsign) electrooptical (period) net
http://electrooptical.net

George Herold

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Feb 18, 2011, 1:33:47 PM2/18/11
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On Feb 18, 10:31 am, Phil Hobbs

<pcdhSpamMeSensel...@electrooptical.net> wrote:
> k...@att.bizzzzzzzzzzzz wrote:
> > On Wed, 16 Feb 2011 18:29:01 -0800, Rich Grise<ri...@example.net.invalid>
> > wrote:
>
> >> John Fields wrote:
>
> >>> sprinkled with oregano and drizzled with extra virgin olive oil for
> >>> dinner, so I can't help with that search right now. :-(
>
> >> How is "extra virgin" olive oil different from plain ol' ordinary
> >> everyday olive oil, other than the price?
>
> > "Virgin" means that it's olive oil (no chemicals added).  "Extra-virgin" means
> > it's from the "first pressing" of the olives and is supposed to be better.
> > Neither of these terms have any legal meaning and the meaning words, if not
> > the oil, are often adulterated.
>
> It means that it's green and putrid-tasting.  You have to add balsamic
> vinegar to cut the taste, and then put it over bad-tasting 'baby greens'
> to make a modern salad.  Ain't progress wonderful. :(
>
> Cheers
>
> Phil "plain lettuce forever" Hobbs

Oh, Honeymoon salad?

"Lettuce alone, undressed."

George H.


>
> --
> Dr Philip C D Hobbs
> Principal
> ElectroOptical Innovations
> 55 Orchard Rd
> Briarcliff Manor NY 10510
> 845-480-2058
>

> email: hobbs (atsign) electrooptical (period) nethttp://electrooptical.net- Hide quoted text -

Phil Hobbs

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Feb 18, 2011, 2:02:54 PM2/18/11
to
George Herold wrote:
> On Feb 18, 10:31 am, Phil Hobbs
> <pcdhSpamMeSensel...@electrooptical.net> wrote:
>> k...@att.bizzzzzzzzzzzz wrote:
>>> On Wed, 16 Feb 2011 18:29:01 -0800, Rich Grise<ri...@example.net.invalid>
>>> wrote:
>>
>>>> John Fields wrote:
>>
>>>>> sprinkled with oregano and drizzled with extra virgin olive oil for
>>>>> dinner, so I can't help with that search right now. :-(
>>
>>>> How is "extra virgin" olive oil different from plain ol' ordinary
>>>> everyday olive oil, other than the price?
>>
>>> "Virgin" means that it's olive oil (no chemicals added). "Extra-virgin" means
>>> it's from the "first pressing" of the olives and is supposed to be better.
>>> Neither of these terms have any legal meaning and the meaning words, if not
>>> the oil, are often adulterated.
>>
>> It means that it's green and putrid-tasting. You have to add balsamic
>> vinegar to cut the taste, and then put it over bad-tasting 'baby greens'
>> to make a modern salad. Ain't progress wonderful. :(n

>>
>> Cheers
>>
>> Phil "plain lettuce forever" Hobbs
>
> Oh, Honeymoon salad?
>
> "Lettuce alone, undressed."
>
> George H.
>>

:)

Cheers

Phil Hobbs

Rich Grise

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Feb 18, 2011, 6:23:11 PM2/18/11
to
George Herold wrote:
> On Feb 18, 10:31 am, Phil Hobbs
>> k...@att.bizzzzzzzzzzzz wrote:
>> > On Wed, 16 Feb 2011 18:29:01 -0800, Rich
>> > Grise<ri...@example.net.invalid> wrote:
>> >> John Fields wrote:
>>
>> >>> sprinkled with oregano and drizzled with extra virgin olive oil for
>> >>> dinner, so I can't help with that search right now. :-(
>>
>> >> How is "extra virgin" olive oil different from plain ol' ordinary
>> >> everyday olive oil, other than the price?
>>
>> > "Virgin" means that it's olive oil (no chemicals added).
>> > "Extra-virgin" means it's from the "first pressing" of the olives and
>> > is supposed to be better. Neither of these terms have any legal meaning
>> > and the meaning words, if not the oil, are often adulterated.
>>
>> It means that it's green and putrid-tasting.  You have to add balsamic
>> vinegar to cut the taste, and then put it over bad-tasting 'baby greens'
>> to make a modern salad.  Ain't progress wonderful. :(
>> Phil "plain lettuce forever" Hobbs
>
> Oh, Honeymoon salad?
>
> "Lettuce alone, undressed."
>
I like my salad like I like my women - not dressed. ;-)

Cheers!
Rich

Jasen Betts

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Feb 19, 2011, 4:13:09 AM2/19/11
to
On 2011-02-17, George Herold <ghe...@teachspin.com> wrote:
> On Feb 17, 7:38 am, John Fields <jfie...@austininstruments.com> wrote:
>> On Wed, 16 Feb 2011 12:23:18 -0800 (PST), George Herold

>> > How 'bout something else... surely there's lots of ways to sense the
>> >RPM of a motor.  Can you pick off a signal that does the spark
>> >timing?  Maybe a coil wrapped about the spark plug wire?

>> As a capacitive pick-off?

> No, I was thinking about sensing the current in the coil....

I think John was picturing your descritionj being a coil wound round the plug
lead. I can see a way to wrap a coil round a plug lead and achieve
magnetic coupling, it'd be wrapped in such a way as to form a toroid
shape.

> better to work on the primary side as Whit3rd suggested.

Yes, this is how most automotive tachometers work.

anoter way to do it would be to sense the leaking magneic field of the
spark coil.

or to put a coil in a magnetic field near the ring gear on the
flywheel (or tap the one that's already present in many vehicles)

--
⚂⚃ 100% natural

Bob Masta

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Feb 19, 2011, 8:17:39 AM2/19/11
to
On Thu, 17 Feb 2011 13:58:18 -0600, John Fields
<jfi...@austininstruments.com> wrote:

>You can't sense the current in a conductor by wrapping a coil of wire
>around it.
>

Several turns of wire around a spark plug wire will work
just fine for tachometer purposes. With a simple limiter
you can read the RPM directly using a sound card. See
"Engine RPM Measurement" at
<http://www.daqarta.com/dw_0a0r.htm>.

Best regards,


Bob Masta

DAQARTA v6.00
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, Sound Level Meter
Frequency Counter, FREE Signal Generator
Pitch Track, Pitch-to-MIDI
Science with your sound card!

whit3rd

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Feb 19, 2011, 1:25:28 PM2/19/11
to
On Feb 19, 5:17 am, N0S...@daqarta.com (Bob Masta) wrote:
> On Thu, 17 Feb 2011 13:58:18 -0600, John Fields
>
> <jfie...@austininstruments.com> wrote:
> >You can't sense the current in a conductor by wrapping a coil of wire
> >around it.
>
> Several turns of wire around a spark plug wire will work
> just fine for tachometer purposes.

Both these statements are right. A 'coil of wire around it' doesn't
achieve current sensing unless your winding is not a simple
wraparound, because it's parallel windings that have flux
coupling. The wire-around sensor is a capacitive (voltage
spike) sense transducer, not a current transducer.

John Fields

unread,
Feb 19, 2011, 2:27:54 PM2/19/11
to
On Sat, 19 Feb 2011 13:17:39 GMT, N0S...@daqarta.com (Bob Masta)
wrote:

>On Thu, 17 Feb 2011 13:58:18 -0600, John Fields
><jfi...@austininstruments.com> wrote:
>
>>You can't sense the current in a conductor by wrapping a coil of wire
>>around it.
>>
>
>Several turns of wire around a spark plug wire will work
>just fine for tachometer purposes.

---
That wasn't the point, though.

---
JF

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