For many years, the airport Schiphol in the hall with luggage belts and
the adjacent waiting area for pickup
have been using a system like this, where the light follows movements.
The only consequence is that if you sit down to wait for your luggage
and there is nobody moving near you,
then the light dims and you are in what feels like twilight while moving
passengers "take the light with them".
Modern LED bulbs make dimming trivial and efficient, old style
incandescent could be dimmed but lost
efficiency much faster than that the power dropped, in other words:
consumption did not go down much,
only light output. Halogen lights cannot normally be dimmed continuously
without seriously affecting life, as their
extended life and increased efficiency depend on the bulb's filament
being hot enough to deposit evaporated
metal back, picked up from the colder glass by the halogen gass.
(Note that modern incandescents often are a small plug-in halogen bulb
welded to two wires inside the larger glass "pear".)

The trick in having a comfortable amount of light without the on/off
behavior of the security motion-sensing lights
is simply that the (analog) output of the motion sensor should control
the LED dimming, after going through a filter
that has a fast attack and slow decay time delay (RC filter plus diode)
so the light brightens quickly when you move
nearby but then takes a long time to gradually reduce brightness
afterwards. You can choose whether it should dim 
to a sustained light level or that it falls all the way back to dark,
that way you don't even need to use light switches which
can be a welcome relief for disabled who need to adapt an existing home
to reduced mobility without the financial
burden to retrofit all lights to remote control systems.

Note, especially in the short run, it might be easier to create some
fixtures that have this function with built-in motion
sensors and dimmers and can take a regular dimmable (LED) bulb, before
attempting to make LED bulbs with
this function.

One issue with building it into the bulb itself is the
obstruction/orientation problem. Shades and frosting from existing
fixtures can make it difficult for a motion-sensing bulb to detect your
presence. And you might want to detect motion
only in certain directions to avoid movement outside or in an adjacent
room to trigger the light, but the screw-in thread
of regular bulbs make it unpredictable in which direction it will
detect. This can be solved with a movable blinder on the
bulb, but that makes it prone to installation errors.

Still interesting ways to solve efficiency questions.
To tie this back to EVs: my current electric truck uses one motor
winding for boost inductor and one motor inverter IGBT
as switch, despite it only supporting 3kW charging rate which means that
the current is below 10 Amps and it would be
much more efficient to use a dedicated switch and inductor. Just
magnetizing the whole motor costs power, losses in the
large IGBT are high and because of the high losses in motor and
controller, the water pump must be running and after
charging a while even the radiator fan is coming on because the inverter
is getting warm enough to trigger this.

I am planning to replace this inefficient charger (which can lose as
much as 50% of the energy when charging from 110V)
with a simple PFC (Power Factor Correction) input stage of a server
power supply and this should bring my charger
efficiency back up over 95%, requiring only a small fan to cool the
inductor and switching transistor. When I use two
PFC front ends from two supplies then I can even select whether to
charge at 6kW as most public chargers allow, or to
charge at the current 3kW rate that can be handled from a 240V source at
about 12 Amps or even from 110V outlet and
the 12A max inlet current of the PFC front end will limit the charging
to a safe ~1400 Watts.
I may even go as far as controlling the max AC current that is drawn,
which then can take the control from the pilot signal
in a J1772 plug.

-----Original Message-----
From: EV [] On Behalf Of Lee Hart via EV
Sent: Sunday, January 07, 2018 11:19 AM
To: Electric Vehicle Discussion List
Cc: Lee Hart
Subject: Re: [EVDL] Fwd: Self diming street lights

Robert Bruninga via EV wrote:
> here is a brilliant idea in Norway.
> Have the lights dim to 20% when no cars or people are driving by.
> Neat!  Saves 80% of light power while still providing full 
> illumination when someone needs it.

It *is* a good idea. Street lights are a good first application, because
they are expensive enough to afford the extra hardware, and the "bean
counters" that buy them are fanatically interested in minimizing
operating cost.

I had an opportunity to work with the legendary Hans Camenzind (designer
of the 555 timer, among other things). He felt we were going in the
wrong direction with integrated circuits. We were making them ever more
complicated, to do BIG things. What they *should* be doing is making
them simpler, to do SMALL things very well. For example, a pocket
calculator, which has exactly one chip. Thus they are produced by the
billions, easy to use, run on solar power, sell for $1, and work for

But today's designers aren't looking for such applications. They spend
all their time designing smartphones and computers, massively complex
devices that cost a lot, eat lots of power, are hard to learn, full of
bugs, and only last a few years.

One of his "missing products" was the smart bulb. It basically detects
people, and is on when they are near, and dims progressively as they
move away. As you move about your house, the lights are only on where
*you* are. Not like cheap motion-detecting lamps, these would smoothly
dim and brighten so the illumination where you are says about the same.

Another was the smart doorknob. Grab it, and it recognizes you and lets
you in (or locks if you're the wrong person).

Designers occasionally work on such devices, but wind up with massively
complex expensive solutions. The key KISS -- Keep It Simple, Stupid. You
don't want a light bulb that has an IP address, requires a network
connection, needs a linux computer somewhere to run it, and an IT person
to program it. You have to be able to just screw it in, and you're done.

Designing complex things is easy. Designing simple things is HARD!
Whether we or our politicians know it or not, Nature is party to all our
deals and decisions, and she has more votes, a longer memory, and a
sterner sense of justice than we do. -- Wendell Berry
Lee Hart, 814 8th Ave N, Sartell MN 56377,
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