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Finding a loop detector



 
 
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  #11  
Old October 15th 13, 02:29 AM posted to rec.bicycles.tech
datakoll
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Posts: 7,793
Default Finding a loop detector

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  #12  
Old October 15th 13, 02:34 AM posted to rec.bicycles.tech
datakoll
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Posts: 7,793
Default Finding a loop detector

eyeyehahhaha wishful thinKing 360....try 200 pounds THUMP. FIND THE SENSITIVE AREA...I ASSUME ON THE LEAD GOING BACK TO THE SWTICH BOX.

Speak with your engineer...ak abt going to light/ultrasonic beam triggers.

Look for the subject as a legal issue....tampering with those controls is deafinitly illegal. as chaos with social liability. .
  #13  
Old October 15th 13, 02:59 AM posted to rec.bicycles.tech
Jeff Liebermann
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Posts: 4,018
Default Finding a loop detector

On Mon, 14 Oct 2013 10:10:57 -0700 (PDT), Frank Krygowski
wrote:

So: Anyone know the easiest way to determine the exact location
of such a buried coil?


The compass, stud finder, and divining rod will not work. What you
need is a coil resonant to the operating frequency, some kind of
detector, and an indicator. The problem is that the frequencies used
vary from 10 Khz to as high as 200 Khz. That means either a broadband
detector, or a tunable coil.
http://en.wikipedia.org/wiki/Induction_loop

If you have a smartphone of some flavor, you can probably use one of
the oscilloscope apps to act as the amplifier, detector, and display.
Something like this:
https://play.google.com/store/apps/details?id=com.nfx.noscpro&hl=en
There are also various "ghost finder" and "EMF detector" apps that are
basically LF (low frequency) signal detectors. For example:
https://play.google.com/store/apps/details?id=com.superphunlabs.emf&hl=en
https://play.google.com/store/apps/details?id=com.codebros.emffree&hl=en
They use the phones magnetic sensor as a LF pickup coil. I have no
idea of the operating frequency range or sensitivity, but methinks
it's worth trying.

Otherwise, I would build a resonant pickup coil, setup a tuning system
(switched caps and tuning capacitor), mount it on a wooden stick, and
plug the coil into the microphone input. Then use an oscilloscope
application to view the signal. If the signal is low, add a battery
powered audio amp. If you want, I can throw something together (time
permitting) and see what it produces.




--
Jeff Liebermann
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
  #14  
Old October 15th 13, 03:09 AM posted to rec.bicycles.tech
Jay Beattie
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Posts: 4,322
Default Finding a loop detector

On Monday, October 14, 2013 6:59:41 PM UTC-7, Jeff Liebermann wrote:
On Mon, 14 Oct 2013 10:10:57 -0700 (PDT), Frank Krygowski

wrote:



So: Anyone know the easiest way to determine the exact location


of such a buried coil?




The compass, stud finder, and divining rod will not work. What you

need is a coil resonant to the operating frequency, some kind of

detector, and an indicator. The problem is that the frequencies used

vary from 10 Khz to as high as 200 Khz. That means either a broadband

detector, or a tunable coil.

http://en.wikipedia.org/wiki/Induction_loop



If you have a smartphone of some flavor, you can probably use one of

the oscilloscope apps to act as the amplifier, detector, and display.

Something like this:

https://play.google.com/store/apps/details?id=com.nfx.noscpro&hl=en

There are also various "ghost finder" and "EMF detector" apps that are

basically LF (low frequency) signal detectors. For example:

https://play.google.com/store/apps/details?id=com.superphunlabs.emf&hl=en

https://play.google.com/store/apps/details?id=com.codebros.emffree&hl=en

They use the phones magnetic sensor as a LF pickup coil. I have no

idea of the operating frequency range or sensitivity, but methinks

it's worth trying.



Otherwise, I would build a resonant pickup coil, setup a tuning system

(switched caps and tuning capacitor), mount it on a wooden stick, and

plug the coil into the microphone input. Then use an oscilloscope

application to view the signal. If the signal is low, add a battery

powered audio amp. If you want, I can throw something together (time

permitting) and see what it produces.


So, is there a cell phone app for triggering the loop?

-- Jay Beattie.
  #15  
Old October 15th 13, 03:30 AM posted to rec.bicycles.tech
James[_8_]
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Posts: 6,153
Default Finding a loop detector

On 15/10/13 12:59, Jeff Liebermann wrote:
On Mon, 14 Oct 2013 10:10:57 -0700 (PDT), Frank Krygowski
wrote:

So: Anyone know the easiest way to determine the exact location
of such a buried coil?


The compass, stud finder, and divining rod will not work. What you
need is a coil resonant to the operating frequency, some kind of
detector, and an indicator. The problem is that the frequencies used
vary from 10 Khz to as high as 200 Khz. That means either a broadband
detector, or a tunable coil.
http://en.wikipedia.org/wiki/Induction_loop

If you have a smartphone of some flavor, you can probably use one of
the oscilloscope apps to act as the amplifier, detector, and display.
Something like this:
https://play.google.com/store/apps/details?id=com.nfx.noscpro&hl=en
There are also various "ghost finder" and "EMF detector" apps that are
basically LF (low frequency) signal detectors. For example:
https://play.google.com/store/apps/details?id=com.superphunlabs.emf&hl=en
https://play.google.com/store/apps/details?id=com.codebros.emffree&hl=en
They use the phones magnetic sensor as a LF pickup coil. I have no
idea of the operating frequency range or sensitivity, but methinks
it's worth trying.

Otherwise, I would build a resonant pickup coil, setup a tuning system
(switched caps and tuning capacitor), mount it on a wooden stick, and
plug the coil into the microphone input. Then use an oscilloscope
application to view the signal. If the signal is low, add a battery
powered audio amp. If you want, I can throw something together (time
permitting) and see what it produces.



You will have fun listening to 200kHz signals with a microphone input
circuit and A/D. Often the maximum sample rate is 192kHz for high end
audio A/D converters. I don't know what phone circuits are capable of,
but I'd be surprised if it was that high.

--
JS

  #16  
Old October 15th 13, 03:43 AM posted to rec.bicycles.tech
Jay Beattie
external usenet poster
 
Posts: 4,322
Default Finding a loop detector

On Monday, October 14, 2013 7:30:26 PM UTC-7, James wrote:
On 15/10/13 12:59, Jeff Liebermann wrote:

On Mon, 14 Oct 2013 10:10:57 -0700 (PDT), Frank Krygowski


wrote:




So: Anyone know the easiest way to determine the exact location


of such a buried coil?




The compass, stud finder, and divining rod will not work. What you


need is a coil resonant to the operating frequency, some kind of


detector, and an indicator. The problem is that the frequencies used


vary from 10 Khz to as high as 200 Khz. That means either a broadband


detector, or a tunable coil.


http://en.wikipedia.org/wiki/Induction_loop




If you have a smartphone of some flavor, you can probably use one of


the oscilloscope apps to act as the amplifier, detector, and display.


Something like this:


https://play.google.com/store/apps/details?id=com.nfx.noscpro&hl=en


There are also various "ghost finder" and "EMF detector" apps that are


basically LF (low frequency) signal detectors. For example:


https://play.google.com/store/apps/details?id=com.superphunlabs.emf&hl=en


https://play.google.com/store/apps/details?id=com.codebros.emffree&hl=en


They use the phones magnetic sensor as a LF pickup coil. I have no


idea of the operating frequency range or sensitivity, but methinks


it's worth trying.




Otherwise, I would build a resonant pickup coil, setup a tuning system


(switched caps and tuning capacitor), mount it on a wooden stick, and


plug the coil into the microphone input. Then use an oscilloscope


application to view the signal. If the signal is low, add a battery


powered audio amp. If you want, I can throw something together (time


permitting) and see what it produces.








You will have fun listening to 200kHz signals with a microphone input

circuit and A/D. Often the maximum sample rate is 192kHz for high end

audio A/D converters. I don't know what phone circuits are capable of,

but I'd be surprised if it was that high.



--

JS


O.K., in that case, I'll continue my practice of dragging a '69 Malibu hood behind my bike to trigger the loops.

BTW, I have a friend who is convinced that you can treat a non-responsive turn signal as "broken" and may permissibly run the light. After ferreting through our version of the UVC, I found nothing to support that belief -- meaning that you can't run the light if you don't trigger the loop. I'm not clear on what you are supposed to do, however. I run the light -- but I look for cops first.

-- Jay Beattie.
  #17  
Old October 15th 13, 03:45 AM posted to rec.bicycles.tech
Frank Krygowski[_2_]
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Posts: 7,511
Default Finding a loop detector

On Monday, October 14, 2013 9:59:41 PM UTC-4, Jeff Liebermann wrote:
If you want, I can throw something together (time
permitting) and see what it produces.


Well sure, if you like. But I'm hoping for something as simple as possible.

I've posted the question on a couple other lists. Before putting any time into it, you might want to wait to see if there's a known solution out there. Thanks for the offer, though.

- Frank Krygowski
  #18  
Old October 15th 13, 04:05 AM posted to rec.bicycles.tech
James[_8_]
external usenet poster
 
Posts: 6,153
Default Finding a loop detector

On 15/10/13 13:43, Jay Beattie wrote:

O.K., in that case, I'll continue my practice of dragging a '69
Malibu hood behind my bike to trigger the loops.

BTW, I have a friend who is convinced that you can treat a
non-responsive turn signal as "broken" and may permissibly run the
light. After ferreting through our version of the UVC, I found
nothing to support that belief -- meaning that you can't run the
light if you don't trigger the loop. I'm not clear on what you are
supposed to do, however. I run the light -- but I look for cops
first.


I think our cops recommend you dismount and become a pedestrian.

I, like you, often run the light if it doesn't sense me, when safe to do
so.

I have found that riding in circles over the sensor area sometimes
encourages it to detect me. Just watch for cars when doing so. There
are times when it is never very safe to turn due to a continual stream
of traffic.

I've also stopped on the sensor, not triggered it, and had a car pull up
behind me that is too far back to trigger it. I then need to move
forward, and encourage the driver to move forward over the sensor area.
It all gets a bit of a nuisance at times.

--
JS



  #19  
Old October 15th 13, 04:13 AM posted to rec.bicycles.tech
Dan
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Posts: 896
Default Finding a loop detector

Frank Krygowski writes:

On Monday, October 14, 2013 9:59:41 PM UTC-4, Jeff Liebermann wrote:
If you want, I can throw something together (time
permitting) and see what it produces.



(Just a _tiny bit_ more context would have made a world of
difference here. The subject line helps some, but seriously -
look at the body of your post - no hint what you're talking
about. Comically so.)

Well sure, if you like. But I'm hoping for something as simple as possible.


The simple solution is to assume the sensor will never detect
you or your bicycle anyway, only consider the light's status as
it pertains to what other people are apt to do, then proceed
accordingly.

I've posted the question on a couple other lists. Before putting any time into it, you might want to wait to see if there's a known solution out there.


Where's the fun in that? (Unless you happen to turn up a sonic
screwdriver.)

Thanks for the offer, though.

  #20  
Old October 15th 13, 04:30 AM posted to rec.bicycles.tech
[email protected]
external usenet poster
 
Posts: 445
Default Finding a loop detector

On Mon, 14 Oct 2013 19:43:37 -0700 (PDT), Jay Beattie
wrote:

On Monday, October 14, 2013 7:30:26 PM UTC-7, James wrote:
On 15/10/13 12:59, Jeff Liebermann wrote:

On Mon, 14 Oct 2013 10:10:57 -0700 (PDT), Frank Krygowski


wrote:




So: Anyone know the easiest way to determine the exact location


of such a buried coil?




The compass, stud finder, and divining rod will not work. What you


need is a coil resonant to the operating frequency, some kind of


detector, and an indicator. The problem is that the frequencies used


vary from 10 Khz to as high as 200 Khz. That means either a broadband


detector, or a tunable coil.


http://en.wikipedia.org/wiki/Induction_loop




If you have a smartphone of some flavor, you can probably use one of


the oscilloscope apps to act as the amplifier, detector, and display.


Something like this:


https://play.google.com/store/apps/details?id=com.nfx.noscpro&hl=en


There are also various "ghost finder" and "EMF detector" apps that are


basically LF (low frequency) signal detectors. For example:


https://play.google.com/store/apps/details?id=com.superphunlabs.emf&hl=en


https://play.google.com/store/apps/details?id=com.codebros.emffree&hl=en


They use the phones magnetic sensor as a LF pickup coil. I have no


idea of the operating frequency range or sensitivity, but methinks


it's worth trying.




Otherwise, I would build a resonant pickup coil, setup a tuning system


(switched caps and tuning capacitor), mount it on a wooden stick, and


plug the coil into the microphone input. Then use an oscilloscope


application to view the signal. If the signal is low, add a battery


powered audio amp. If you want, I can throw something together (time


permitting) and see what it produces.








You will have fun listening to 200kHz signals with a microphone input

circuit and A/D. Often the maximum sample rate is 192kHz for high end

audio A/D converters. I don't know what phone circuits are capable of,

but I'd be surprised if it was that high.



--

JS


O.K., in that case, I'll continue my practice of dragging a '69 Malibu hood behind my bike to trigger the loops.

BTW, I have a friend who is convinced that you can treat a non-responsive turn signal as "broken" and may permissibly run the light. After ferreting through our version of the UVC, I found nothing to support that belief -- meaning that you can't run the light if you don't trigger the loop. I'm not clear on what you are supposed to do, however. I run the light -- but I look for cops first.

-- Jay Beattie.

MOST loop trigger intersections also have a "push to walk" switch. I
get off the bike, walk over and punch the button, then go back and
wait for the light, or "jaywalk" with the bike.
 




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