Thinking Outside The Box

On 3/15/2012 1:00 AM, Ralph Barone wrote:
Peter wrote:
On 3/13/2012 11:19 PM, James wrote:
On 14/03/12 14:09, Peter Cole wrote:
On 3/13/2012 5:00 PM, James wrote:
snip

I'm not sure what point you're attempting to make.

It appears that in the quoted conversation above, you believe that "by
definition" the use of a switching regulator results in the LED being
switched ON and OFF at a high rate.

If that is what you meant, you are incorrect.


You do like to split hairs. You are rather arbitrarily deciding that
"switching an LED on and off" means zero current.

What is your definition of "OFF"? Where I come from OFF = 0.

The "switch" in a switching regulator is either on or off, by
definition. In that sense, a LED is not switched. The switch is the FET
in this circuit. The current in the LED may go to zero in the primary
(full power) cycle, or may not. In dimmed mode, it will typically always
go to zero.

On 3/15/2012 1:00 AM, Ralph Barone wrote:
Peter wrote:
On 3/12/2012 11:42 PM, Ralph Barone wrote:
Peter wrote:
On 3/12/2012 5:50 AM, Phil W Lee wrote:
Jeff considered Sun, 11 Mar 2012
16:09:07 -0700 the perfect time to write:

On Sun, 11 Mar 2012 15:26:01 -0700,
wrote:

On 3/11/2012 3:16 PM, Jeff Liebermann wrote:

Trivia: All high power (0.5w) LED lights use PWM (pulse width
modulation) for dimming, to control heating, and to improve
efficiency. Even in the full brightness mode, they flash. You can
see the PWM with a photo diode and oscilloscope, or just shine the
light on a rotating colored disk to see the strobe effect. I wonder
if Germany considers this as a flashing bicycle light.

I would view the Wikipedia article on bicycle lighting with a lot of
grains of salt. It's been hijacked by several individuals with a
specific agenda. A huge number of obvious errors and if you try to
correct them, someone undoes the correction.

I don't see any evidence of hijacking or an agenda in the history
since 2005:
http://en.wikipedia.org/w/index.php?title=Bicycle_lighting&offset=&limit=500 &action=history
Looks like mostly additions, spelling corrections, juggling
references, and discussions (talk). Which individuals are allegedly
responsible?

If you're referring to my mention of PWM in bicycle lighting, that was
verified by me with several LED flashlights and one Bike Planet
bicycle headlight. At such power levels, one would need to be a
masochist to use a linear regulator (except in retrofit flashlight
bulbs). Would you like me to post an oscilloscope photo?

So based on your analysis of ONE bicycle light, you assert that all
use PWM?
Why on earth would they?
All you need is a current limiting device, which is typically a
resistor,

No, it's typically a switching regulator, which modulates duty cycle, AKA PWM.

The use of a switching regulator does not necessarily result in the LED
being switched ON and OFF at a high rate.

I think it does, by definition.

I beg to disagree. Your PC power supply contains a switching regulator, yet
it produces constant DC voltages. A buck converter for LED lighting use
could be designed to produce any desired amount of "flicker", right down to
essentially zero if desired.
Yes, obviously the PC doesn't switch on & off rapidly, the regulation
transistors do. The power supply has a finite amount of ripple at a
frequency equal to the switching frequency. I suppose the term
"constant" is relative to the amount of ripple. The degree of ripple
regulation required is determined by the ripple tolerance of the load
devices. If the load was heating elements, 100% ripple might be fine,
CPU's & RAM's, not so much.

A buck converter for LED lighting use
could be designed to produce any desired amount of "flicker", right down to
essentially zero if desired.

If by "flicker" you mean ripple, then yes, it can be set by the amount
of stored energy between the switching cycles, via inductors (stored
current) or capacitors (stored voltage), and the switching cycle period.
"Essentially zero" means essentially infinite inductance/capacitance or
frequency, though.


I haven't analyzed any, so I
can't comment on how many bike light current regulators PWM the LED, versus
more sophisticated control methods.

As an EE, I can't think of any more "sophisticated" method, unless you're
modulating it to send data or something. FWIW, I've designed a few PWM
circuits for lamp (arc) control, a few switching power supply regulators
and a motor controller or 2.

OK, unclear language on my part. What I meant to say was that I didn't know
how many lights did a raw PWM on the LED (and relied on the inherent
current limiting of the battery ESR to avoid frying the LED) and how many
employed actual switching current regulators, which may have some residual
ripple, but effectively provide a constant DC current to the LED.

The difference between "raw" PWM and "sophisticated" PWM is the addition
of an inductor, basically. I suppose a really cheap device could leave
out the inductor if the battery ESR was high and/or the voltage matched
the LED operating voltage well enough, but I don't really see the point.
If that was true, you could leave out the regulator entirely, except for
dimming/flashing.

If you didn't care about peak LED (or switch) current, hence ripple, you
could simply vary the switch duty cycle, sense the RMS current, and feed
back to regulate. Adding an inductor (and catch diode) simply lowers the
peak current and ripple. The ripple could go to zero with an
appropriately high peak. If the LED is battery operated, the peak would
be limited by the battery & switch(on) effective series resistance,
proportional to the difference in voltage between the battery and the
LED forward voltage.

Since most of the LED lights I have used seem to run at rated LED
currents at full brightness (i.e. don't derate the LED), and LED
efficiency drops off with current far below maximum (peak efficiency
50% Imax), it wouldn't seem to make sense to allow peak current to go
over Imax from an efficiency standpoint, even if it didn't damage
anything, so it seems like even the cheapest lights run the regulators
in "continuous" mode (LED current never goes to zero in the switching
cycle) at full power setting.

More simply put, if you want to run a 3.5V LED from a 7V battery, you'll
have ~50% duty cycle switching at whatever frequency you choose. The
current ripple will be set by the inductor size and switching frequency.
Iavg could result from switching between 0 and 2xIavg, or -0.001Iavg and
+0.001Iavg. The first case might seem impossible because of LED/switch
ratings, but Imax is often a thermal consideration, so at high enough
frequency it wouldn't necessarily be impractical.

My cheapest power LED device is a 2xAA cell 3W flashlight. It has a
buck/boost circuit, since it will run on a single AA cell (NiMh). That
light cost $12, so I think "sophisticated" power management isn't an
economic issue with any of these lights.


PS: Would you consider hysteretic PWM to be a different beast from regular
(compare desired waveform to triangle reference, switch transistors
accordingly) PWM?

Not really, they're basically the same depending on whether you want to
hold ripple or frequency constant.

On 16/03/12 04:41, Duane Hebert wrote:
On 3/15/2012 11:03 AM, SMS wrote:
On 3/14/2012 6:50 PM, John B. wrote:

Out of curiosity, how long will your phone battery last when tracking
with the GPS? I've tried it with two different phones and neither
would last until I got back from my Sunday ride.
I tried with straight GPS and assisted GPS and in either case the
battery was dead when I got home.

On my Android phone the GPS drains the battery in about an hour. A GPS
uses a lot of power. You could get a battery sleeve for the iPhone to
increase the run time.


An hour? Even with the screen closed? I guess I'll find out as a friend
soaked his iPhone sailing and switched to Android.

I don't think that the *OS* can be directly compared for battery life.
There are many phones running Android OS, with different hardware.
Battery capacity, CPU speed and display size and backlight make
differences, not so much the OS.

Running the GPS module will use a bit more, and again it depends on the
type of GPS.

Perhaps this is a good example for Mr Liebermann to invest in designing
a universal phone charger powered by a bicycle dynamo - though I won't
be using one.

--
JS.

On 3/15/2012 5:14 PM, James wrote:
On 16/03/12 04:41, Duane Hebert wrote:
On 3/15/2012 11:03 AM, SMS wrote:
On 3/14/2012 6:50 PM, John B. wrote:

Out of curiosity, how long will your phone battery last when tracking
with the GPS? I've tried it with two different phones and neither
would last until I got back from my Sunday ride.
I tried with straight GPS and assisted GPS and in either case the
battery was dead when I got home.

On my Android phone the GPS drains the battery in about an hour. A GPS
uses a lot of power. You could get a battery sleeve for the iPhone to
increase the run time.


An hour? Even with the screen closed? I guess I'll find out as a friend
soaked his iPhone sailing and switched to Android.

I don't think that the *OS* can be directly compared for battery life.
There are many phones running Android OS, with different hardware.
Battery capacity, CPU speed and display size and backlight make
differences, not so much the OS.

Running the GPS module will use a bit more, and again it depends on
the type of GPS.

Perhaps this is a good example for Mr Liebermann to invest in
designing a universal phone charger powered by a bicycle dynamo -
though I won't be using one.



Not sure what part of that is the OS and what part is the hardware.
There are no iPhones running Android OS AFAIK.
Like I said, I will see when my friend starts riding with his Android.

Anyway, before I would use a dynamo to charge my phone I would buy a
Garmin. I doubt that I will do either though.

On Thu, 15 Mar 2012 06:23:34 -0400, Duane Hebert
wrote:

On 3/14/2012 9:50 PM, John B. wrote:
On Wed, 14 Mar 2012 13:39:50 -0400,
wrote:

On 03/14/2012 01:25 PM, Peter Cole wrote:
On 3/14/2012 10:17 AM, Duane wrote:
On 03/14/2012 09:36 AM, sms88 wrote:
On 3/14/2012 4:05 AM, Duane Hebert wrote:

LOL. Last one for me was when I asked my son why his touch screen was
shattered again.
"Took a puck, dad." Why you need a cell phone in your pocket when
you're
playing hockey is sort of beyond me.
But then again, I'm "so twentieth century."
I'm thinking of getting my kids a second phone, a cheap flip phone, to
take to school or on trips. $30/year on Pageplus (Verizon MVNO), and
there's really no reason they need a smart phone at school. At least
they don't have iPhones which are often stolen, only $100 gently used
HTC Incredibles on Pageplus. I used to think there was no reason to have
a phone at school at all, until two recent code-red incidents at their
school. It was good to be able to send and receive texts with news of
what was happening because the students were scared and knew nothing of
what was happening.

He has a cheap phone now and an iPod Touch for his music and WIFI. The
iPod is on its 3rd screen. He also has blue tooth head phones because
the plugs keep getting screwed up.
My daughter (college frosh) has the same setup. She uses an ancient flip
phone for calls& text and an iTouch for surf& music on school or home
WiFi. She's too frugal for a data plan (me so proud). When I got her the
touch, I put it in a semi-case, having heard so many cracked screen
stories, so far so good. My son, on the other hand, was an early smart
phone adapter, he's on his fourth or fifth, I've lost count, I think his
carrier will own him well into middle age, but it's his money (mostly).

I considered getting an iTouch for myself, after seeing my friends
iPhone in action last year. The idea of a nice GPS unit combined with
Google maps seemed like a cyclist's dream come true. Instead, I got a
Kindle Fire because the format seemed so much more useful for the kind
of stuff I do most of the time. It does have WiFi location, which I
guess works OK in an urban environment. I sideloaded Google maps, and it
appears they cache for when you're out of hotspot range, but I haven't
yet taken it out for a ride. Boston isn't a very large city, but this
season I hope to find some new routes through some dense and unfamiliar
neighborhoods, I hope it will help.

I have a couple of apps on my iPhone to track rides. I use them to map
a ride and share it with some friends. The club also posts the maps in
garmin format that I can import into one of the apps on my phone. I
generally don't need this when riding with the group as there are enough
guys with garmin cycle computers to find our way around.

The one I probably use the most is the yellow pages locator to find the
closest ice cream.
Out of curiosity, how long will your phone battery last when tracking
with the GPS? I've tried it with two different phones and neither
would last until I got back from my Sunday ride.
I tried with straight GPS and assisted GPS and in either case the
battery was dead when I got home.


I have an iPhone 4 and running either MapMyRide, AllSport LE or Strava,
with each set to ignore stops I have been able to record a 5 hour ride.
But this is with the screen off. If I keep the screen on, it lasts only
a couple of hours.

I had not thought of turning the screen off. Just stick the phone in
my pocket and setting off. I'll try that next time.
--
Cheers,

John B.

On Thu, 15 Mar 2012 08:03:31 -0700, SMS
wrote:

On 3/14/2012 6:50 PM, John B. wrote:

Out of curiosity, how long will your phone battery last when tracking
with the GPS? I've tried it with two different phones and neither
would last until I got back from my Sunday ride.
I tried with straight GPS and assisted GPS and in either case the
battery was dead when I got home.

On my Android phone the GPS drains the battery in about an hour. A GPS
uses a lot of power. You could get a battery sleeve for the iPhone to
increase the run time.

I have an option "assisted GPS' that apparently uses phone signals to
augment the GPS data which seems to use less battery, but in either
case the phone. But in either case it wasn't lasting long enough for
any practical use. Will try turning off the screen, as someone
suggested, next time.
--
Cheers,

John B.

On Thu, 15 Mar 2012 17:42:56 -0400, Duane Hebert
wrote:

On 3/15/2012 5:14 PM, James wrote:
On 16/03/12 04:41, Duane Hebert wrote:
On 3/15/2012 11:03 AM, SMS wrote:
On 3/14/2012 6:50 PM, John B. wrote:

Out of curiosity, how long will your phone battery last when tracking
with the GPS? I've tried it with two different phones and neither
would last until I got back from my Sunday ride.
I tried with straight GPS and assisted GPS and in either case the
battery was dead when I got home.

On my Android phone the GPS drains the battery in about an hour. A GPS
uses a lot of power. You could get a battery sleeve for the iPhone to
increase the run time.


An hour? Even with the screen closed? I guess I'll find out as a friend
soaked his iPhone sailing and switched to Android.

I don't think that the *OS* can be directly compared for battery life.
There are many phones running Android OS, with different hardware.
Battery capacity, CPU speed and display size and backlight make
differences, not so much the OS.

Running the GPS module will use a bit more, and again it depends on
the type of GPS.

Perhaps this is a good example for Mr Liebermann to invest in
designing a universal phone charger powered by a bicycle dynamo -
though I won't be using one.



Not sure what part of that is the OS and what part is the hardware.
There are no iPhones running Android OS AFAIK.
Like I said, I will see when my friend starts riding with his Android.

The Apple certainly do not run Android.

Anyway, before I would use a dynamo to charge my phone I would buy a
Garmin. I doubt that I will do either though.

I had thought of carrying a fully charged battery and changing mid
ride but that is (to use the modern jargon a pretty dorky solution.
--
Cheers,

John B.

On 3/15/2012 10:41 AM, Duane Hebert wrote:

An hour? Even with the screen closed? I guess I'll find out as a friend
soaked his iPhone sailing and switched to Android.

I have the original Motorola Android phone. Later models may be better.
I think the feeling of the designers was that the GPS was something
you'd use in the car so little effort was made in reducing GPS power
consumption.

On Thu, 15 Mar 2012 20:17:52 -0700, SMS
wrote:

On 3/15/2012 10:41 AM, Duane Hebert wrote:

An hour? Even with the screen closed? I guess I'll find out as a friend
soaked his iPhone sailing and switched to Android.

I have the original Motorola Android phone. Later models may be better.
I think the feeling of the designers was that the GPS was something
you'd use in the car so little effort was made in reducing GPS power
consumption.

Nokia had at least one phone with GPS long before Android arrived. I
think probably it became nearly a standard feature with android phones
simply so they could have the "offer everything: option.

I did see one crafty use for GPS though. If you park in a big parking
area turn on your phone and set a way point. then when you come out
with all your bags of goodies you use the go to function to guide you
to your car.
--
Cheers,

John B.

On 3/15/2012 11:17 PM, SMS wrote:
On 3/15/2012 10:41 AM, Duane Hebert wrote:

An hour? Even with the screen closed? I guess I'll find out as a friend
soaked his iPhone sailing and switched to Android.

I have the original Motorola Android phone. Later models may be better.
I think the feeling of the designers was that the GPS was something
you'd use in the car so little effort was made in reducing GPS power
consumption.

That's probably true. I know that the iPhone 3 was lousy WRT battery
life and gps apps. I'm not a big apple fan but at the time that I was
buying a phone it seemed like the best choice.