Tire Pressure Sensor

[Luhan Monat]

Jim Thompson wrote:

On Fri, 8 Apr 2005 19:57:07 +0100, "Dave Garnett"
dave.garnett@metapurple.co.uk> wrote:


"Luhan Monat" <x@y.z> wrote in message news:Wgi5e.19$EX4.11@fed1read01...

Hi,

I would like to make a remote tire pressure monitor (0-50 psi) for my
bicycle. Any ideas on where to get a sensor cheap? Accuracy is not
critical, as long as temperature drift is not excessive.

Instead of pressure, how about measuring how flat the tyre is ? Insert into
the valve stem a sort of plunger that is spring loaded against the inner
tube and tyre. Every time the wheel goes round the plunger will be
compressed and released. You could make the motion generate a voltage to
turn the electronics on, and then measure the change in inductance to get
the actual distance moved. You might even be able to extract enough power to
power a short transmit burst, and hence need no batteries ...

You would need a filter for an alarm so that the odd bump didn't register,
but a gradual change would ...

Dave



Not bad! But why not a fixed, but compressible, rod as part of the
wheel structure? If it touches repetitively, set off an alarm.

...Jim Thompson
I've just realized that I dont need to transmit any data. I can just

put the whole alarm including pizo noisemaker on the wheel itself
(mounted near the hub). The PIC can wake up every 10 seconds or so,
take a reading, determine if there is a leak, and sound the alarm.

Much thanks for all the ideas.

--
Luhan Monat (luhanis 'at' yahoo 'dot' com)
"The future is not what it used to be..."
http://members.cox.net/berniekm

 

[Joerg]

Hello Luhan,

I've just realized that I dont need to transmit any data. I can just
put the whole alarm including pizo noisemaker on the wheel itself
(mounted near the hub). The PIC can wake up every 10 seconds or so,
take a reading, determine if there is a leak, and sound the alarm.

Then the bike becomes like "modern" cars. One day, after not having used
it for a while, you come into your garage and something is going
beeeeep......beeeeep......

Regards, Joerg

http://www.analogconsultants.com

 

[Jim Thompson]

On Fri, 08 Apr 2005 15:20:02 -0700, Luhan Monat <x@y.z> wrote:

Jim Thompson wrote:
On Fri, 8 Apr 2005 19:57:07 +0100, "Dave Garnett"
dave.garnett@metapurple.co.uk> wrote:


"Luhan Monat" <x@y.z> wrote in message news:Wgi5e.19$EX4.11@fed1read01...

Hi,

I would like to make a remote tire pressure monitor (0-50 psi) for my
bicycle. Any ideas on where to get a sensor cheap? Accuracy is not
critical, as long as temperature drift is not excessive.

Instead of pressure, how about measuring how flat the tyre is ? Insert into
the valve stem a sort of plunger that is spring loaded against the inner
tube and tyre. Every time the wheel goes round the plunger will be
compressed and released. You could make the motion generate a voltage to
turn the electronics on, and then measure the change in inductance to get
the actual distance moved. You might even be able to extract enough power to
power a short transmit burst, and hence need no batteries ...

You would need a filter for an alarm so that the odd bump didn't register,
but a gradual change would ...

Dave



Not bad! But why not a fixed, but compressible, rod as part of the
wheel structure? If it touches repetitively, set off an alarm.

...Jim Thompson
I've just realized that I dont need to transmit any data. I can just
put the whole alarm including pizo noisemaker on the wheel itself
(mounted near the hub). The PIC can wake up every 10 seconds or so,
take a reading, determine if there is a leak, and sound the alarm.

Much thanks for all the ideas.

Actually, the BIG GUY plan is that tires will come from the
manufacturer with an RFID tag and pressure sensor installed.

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

 

[Doug Warner]

Joerg <notthisjoergsch@removethispacbell.net> wrote:

Then the bike becomes like "modern" cars. One day, after not having used
it for a while, you come into your garage and something is going
beeeeep......beeeeep......

Centrifugal switch, or accelerometer. So it only draws power (and

alarms) while moving.

To reply, please remove one letter from each side of "@"
Spammers are VERMIN. Please kill them all.

 

[Paul Hovnanian P.E.]

Joerg wrote:

Hello Luhan,

Trouble is, slow leaks are hard to spot while riding until its way too
late. This is a real issue, worth doing an RF/Micro system on the rear
wheel (which tends to get all the leaks). Test for both pressure level,
and change in pressure to warn as much ahead as possible.

True. But when I was in driving school they still taught us how to watch
for weird behavior of the vehicle. Low pressure, ice, slush etc. They
also taught us how to react.

Most cars are pretty good though. I was at a customer, had half their
R&D Department in a rented Saturn L300 when the right rear decided to
deflate on a county road. None of us even felt much until we were
parked, except that the car became somewhat sluggish. It remained
remarkably stable.

I've had a rear tire sidewall blow out on a Toyota Landcruiser at 70
mph. No problems. It just settled down on the rim. Don't slam on the
brake or steer suddenly and it handles just fine.

--
Paul Hovnanian mailtoaul@Hovnanian.com
------------------------------------------------------------------
ASCII stupid question, get a stupid ANSI!

 

[Paul Hovnanian P.E.]

Luhan Monat wrote:

Joerg wrote:
Hello Spehro,

I would like to make a remote tire pressure monitor (0-50 psi) for my
bicycle. Any ideas on where to get a sensor cheap? Accuracy is not
critical, as long as temperature drift is not excessive.


This is a killer app for cars 'n trucks. Sensor plus uP plus very low
power (eg. Zigbee) wireless interface = big bux for the semiconductor
companies. Especially if it gets government mandated.


It already exists. One of the guys on the German electronics forum
(Oliver Bartels) developed such a system. I believe he also used to race
Formula One rods so he should know what he's talking about.
Unfortunately the pubs are only in German:

http://www.tyretronic.com/index.php?m=200202___AANDE_200201&language=en

In that article it is mentioned that the US mandates it already but I
doubt that.

I can see this for car tires although I check mine every other week. But
for bicycles? On mine I just sit on it and then I know. Usually the
pressure is digital. It is either ok, or it went kapoof.

Regards, Joerg

http://www.analogconsultants.com

Trouble is, slow leaks are hard to spot while riding until its way too
late. This is a real issue, worth doing an RF/Micro system on the rear
wheel (which tends to get all the leaks). Test for both pressure level,
and change in pressure to warn as much ahead as possible.

I already have a micro based alarm system activated by RF remote. So, I
only need to do the hard work on the transmitting end. Something
sending out a code every 10 turns of the wheel or so to save on battery.

I wonder if something along the lines of an RFID chip in the wheel might
be more reliable. No batteries to worry about, it would be powered by
the stationary transceiver.

Yes, these systems already exist; but all I'm lacking is the sensor
itself to make a working device for myself. Also, the commercial ones
dont allow for 'leak rate' detection, they only trip a tranmitter on a
specific pressure.

--
Luhan Monat (luhanis 'at' yahoo 'dot' com)
"The future is not what it used to be..."
http://members.cox.net/berniekm

--
Paul Hovnanian mailtoaul@Hovnanian.com
------------------------------------------------------------------
I want to die quietly in my sleep, like my grandfather,
not screaming in terror, like his passengers.

 

[Paul Hovnanian P.E.]

Doug Warner wrote:

Joerg <notthisjoergsch@removethispacbell.net> wrote:

Then the bike becomes like "modern" cars. One day, after not having used
it for a while, you come into your garage and something is going
beeeeep......beeeeep......

Centrifugal switch, or accelerometer. So it only draws power (and
alarms) while moving.

A tiny generator with an unbalanced weight on the shaft. The generator
spins with the wheel, is shaft is held stationary by the weight (like a
self winding watch).
The generator keeps a small supercap charged and wakes up the monitor
logic when it begins turning.

One could conveivably extract enough power from such a setup to power a
small LED display on the wheel, similar to one of those spinning clocks.
Something I know we all need.

--
Paul Hovnanian mailtoaul@Hovnanian.com
------------------------------------------------------------------
It's easier said than done.
.... and if you don't believe it, try proving that it's easier done than
said, and you'll see that it's easier said that `it's easier done than
said' than it is done, which really proves that it's easier said than
done.

 

[Luhan Monat]

A tiny generator with an unbalanced weight on the shaft. The generator
spins with the wheel, is shaft is held stationary by the weight (like a
self winding watch).
The generator keeps a small supercap charged and wakes up the monitor
logic when it begins turning.

One could conveivably extract enough power from such a setup to power a
small LED display on the wheel, similar to one of those spinning clocks.
Something I know we all need.

This suggests another project. Timed LED's on the wheel that make
patterns or spell out messages at night. Devices such as this are
generally known as 'propeller clocks'.

--
Luhan Monat (luhanis 'at' yahoo 'dot' com)
"The future is not what it used to be..."
http://members.cox.net/berniekm

 

[Michael]

Joerg wrote:

Hello Luhan,

I've just realized that I dont need to transmit any data. I can just
put the whole alarm including pizo noisemaker on the wheel itself
(mounted near the hub). The PIC can wake up every 10 seconds or so,
take a reading, determine if there is a leak, and sound the alarm.

Then the bike becomes like "modern" cars. One day, after not having used
it for a while, you come into your garage and something is going
beeeeep......beeeeep......

Regards, Joerg

http://www.analogconsultants.com

No, that'd not be good. But not as silly as "Your (door; trunk; whatever) is
ajar".

 

[Mac]

On Fri, 08 Apr 2005 21:55:44 -0700, Luhan Monat wrote:

A tiny generator with an unbalanced weight on the shaft. The generator
spins with the wheel, is shaft is held stationary by the weight (like a
self winding watch).
The generator keeps a small supercap charged and wakes up the monitor
logic when it begins turning.

One could conveivably extract enough power from such a setup to power a
small LED display on the wheel, similar to one of those spinning clocks.
Something I know we all need.


This suggests another project. Timed LED's on the wheel that make
patterns or spell out messages at night. Devices such as this are
generally known as 'propeller clocks'.

Actually, I think this would would be good for automotive hubcaps. I think
people would buy them by the thousands if they were cheap enough, and if
there were an easy way to put messages or graphical displays on them.

I wouldn't try to extract power from the rotation, though. I would
just sense the rotation to keep the message upright.

--Mac

 

[John Woodgate]

I read in sci.electronics.design that Spehro Pefhany
<speffSNIP@interlogDOTyou.knowwhat> wrote (in
<budf51dm1h4q0ioe0r3rjb916i9rdi7vqp@4ax.com&gt about 'Tire Pressure
Sensor', on Sat, 9 Apr 2005:

LEDs would be more eye-catching, but would require a power source at
the wheel.

Well, there are fixed and rotating members there, so it's not
impossible.
--
Regards, John Woodgate, OOO - Own Opinions Only.
There are two sides to every question, except
'What is a Moebius strip?'
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

 

[Si Ballenger]

On Sat, 09 Apr 2005 05:37:33 GMT, Mac <foo@bar.net> wrote:

On Fri, 08 Apr 2005 21:55:44 -0700, Luhan Monat wrote:



A tiny generator with an unbalanced weight on the shaft. The generator
spins with the wheel, is shaft is held stationary by the weight (like a
self winding watch).
The generator keeps a small supercap charged and wakes up the monitor
logic when it begins turning.

One could conveivably extract enough power from such a setup to power a
small LED display on the wheel, similar to one of those spinning clocks.
Something I know we all need.


This suggests another project. Timed LED's on the wheel that make
patterns or spell out messages at night. Devices such as this are
generally known as 'propeller clocks'.

Actually, I think this would would be good for automotive hubcaps. I think
people would buy them by the thousands if they were cheap enough, and if
there were an easy way to put messages or graphical displays on them.

I wouldn't try to extract power from the rotation, though. I would
just sense the rotation to keep the message upright.

The below hokeyspokes could probably be adapted to the car tire
hub caps. Back in the 50's you could get hub caps with bearings
and a weighted bottom. It stood still while the tire rotated. I
remember a 55 ford crown vic with this setup. Lowered in the rear
with finder skirts, and the non rotating hub caps on the front.
The hub caps were very big with a picture of a hula girl on them.
Had lights in the front findre wells so you could see the action
at night. Where is my Brill Cream?

http://www.drewish.com/blogger/archives/2005/03/17/2sided_pov_toy.html
http://www.hokeyspokes.com/index.shtml
http://www.treehugger.com/files/2004/12/spoke_n_wheel_l.php

 

[Doug Warner]

"Paul Hovnanian P.E." <Paul@Hovnanian.com> wrote:

A tiny generator with an unbalanced weight on the shaft. The generator
spins with the wheel, is shaft is held stationary by the weight (like a
self winding watch).

No need to go to that length, I have a SmartTire system installed on
my car. The in--tire sensor/transmitters use a pair of lithium coin
cells and last for many years. They transmit every several seconds
for about 5 minutes after starting off, then every 5 minutes. The
receiver lives in the center console.
A bicycle unit, with beeper, could be built into a module that just
screws onto the valve stem.

To reply, please remove one letter from each side of "@"
Spammers are VERMIN. Please kill them all.

 

[Rich Grise]

On Fri, 08 Apr 2005 17:22:31 +0000, Joerg wrote:

Hello Luhan,

Trouble is, slow leaks are hard to spot while riding until its way too
late. This is a real issue, worth doing an RF/Micro system on the rear
wheel (which tends to get all the leaks). Test for both pressure level,
and change in pressure to warn as much ahead as possible.

True. But when I was in driving school they still taught us how to watch
for weird behavior of the vehicle. Low pressure, ice, slush etc. They also
taught us how to react.

Most cars are pretty good though. I was at a customer, had half their R&D
Department in a rented Saturn L300 when the right rear decided to deflate
on a county road. None of us even felt much until we were parked, except
that the car became somewhat sluggish. It remained remarkably stable.

I blew a rear tire on a '76 Plymouth Gran Fury at about 60 MPH once, and

hardly felt it - I knew mainly from the sound. ("What's that noise? Oh!
I've got a blown tire!") I changed the tire in the left-hand breakdown
lane, and the spare was too low to drive on, so I waited for one of those
"highway helper" trucks to come by with some air. When I took the blown
tire, which was basically shreds on a rim, to the tire place, I asked the
tire guy, "Think you can patch that?" He said, "Uh, I don't really think
so - maybe a tube!" ;-)

Cheers!
Rich

 

[Joerg]

Hello Paul,

I've had a rear tire sidewall blow out on a Toyota Landcruiser at 70
mph. No problems. It just settled down on the rim. Don't slam on the
brake or steer suddenly and it handles just fine.

That's exactly what they hammered in. Same as driving on a road where
ice or slippery goo shows up late in the game. Keep the control, don't
panic. This was all pre-ABS and once the brakes locked up there was
hardly anything left to recover.

Regards, Joerg

http://www.analogconsultants.com

 

[Joerg]

Hello Paul,

A tiny generator with an unbalanced weight on the shaft. The generator
spins with the wheel, is shaft is held stationary by the weight (like a
self winding watch).
The generator keeps a small supercap charged and wakes up the monitor
logic when it begins turning.

That's pretty slick. But also expensive.

Regards, Joerg

http://www.analogconsultants.com

 

[Joerg]

Hello Doug,

To reply, please remove one letter from each side of "@"
Spammers are VERMIN. Please kill them all.

Your wish may have been heard. I read in the papers today that a judge
gave one of them a whopping nine years. I think that's a bit much and he
is appealing but it does send a message.

Regards, Joerg

http://www.analogconsultants.com

 

[Terry Given]

Jim Thompson wrote:

On Fri, 08 Apr 2005 17:33:07 GMT, Al <no.spam@wanted.com> wrote:


In article <m5fd511pvnq6ubmm5jrk3b8l800l3b580a@4ax.com>,
Jim Thompson <thegreatone@example.com> wrote:


On Fri, 08 Apr 2005 17:03:25 GMT, Joerg
notthisjoergsch@removethispacbell.net> wrote:


Hello Al,


Another gadget to keep up safe! Jeesh, what ever happened to checking
your tire pressure weekly? The idiots seem to be driving our technology.
More junk to break down and have fixed for yearly inspection.

Common sense seems on the way out. I mean, if people even need a
reminder on coffee cups "caution - HOT - can cause serious injury".

In Europe some folks think they can't even live without ultrasound
parking aids in the bumpers. Oh man.

Regards, Joerg

http://www.analogconsultants.com

In Boston, no ultrasonics need, they park by ear... clang, clang ;-)

...Jim Thompson

In the 60's, while a student, the massive bumpers on my '47 Pontiac
could really dish it out.

Al


I had a '61 Dauphine with tubular wrap-arounds that offered
substantial protection.

...Jim Thompson

The first day in my new apartment in Boston, I was walking to the T and
saw a guy getting into a vehicle that was stuck between 2 others (all in
contact). I was curious to see what he did, so I stopped and watched.
Bang Bang Bang Bang Bang Vroom. I was astounded, but what else could he
do. A week later I was oblivious to such driving, its ubiquitous.

Cheers
Terry

 

[Frithiof Andreas Jensen]

"Joerg" <notthisjoergsch@removethispacbell.net> wrote in message
news:xPy5e.878$RQ7.532@newssvr14.news.prodigy.com...

In Europe some folks think they can't even live without ultrasound
parking aids in the bumpers. Oh man.

Infinately Preferable to VOLVO drivers who use the "rubber fenders" on the
bumpers to gauge the distance ... when parking *and* driving.

 

[David Lesher]

Jim Thompson <thegreatone@example.com> writes:

I had a '61 Dauphine with tubular wrap-arounds that offered
substantial protection.

Anyone who owned a Dauphine must be an experienced engineer; as we
gain experience from failure....

It takes a brave man to own a French car...

--
A host is a host from coast to coast.................wb8foz@nrk.com
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433