On Sun, 08 Jan 2012 12:33:52 -0700, wrote:

Let's look at your list:

Think about something run by a thermostat, low control switch, or
motion detector. They tend to cycle erratically.

A thermostat - refrigerator, freezer, or heating / cooling tends to
cycle at a fairly constant rate, at least for the majority of the time
(an exception would be when a large amount of food is added to a
refrigerator, or a freezer, or when the set temerature of a thermostat
is changed).

I wasn't thinking of an appliance as much as an HVAC system that has a
time adjusted thermostat, and plenty of walk-in or walk-through
traffic. I've worked with a cold storage warehouse where the cooling
system would cycle as you describe as long as nothing was going in or
out. However, when large containers of vegetables went into the
warehouse, the cooler would run for about an hour before it started
cycling evenly as you suggest. Same with HVAC system in areas with
heavy foot traffic.

A motion detector would operate at erratic times, but
not for only 10 seconds.

That depends on what the motion detector is running. I'm thinking
more like a security DVR. When my cheap eBay piece of junk security
DVR detects motion, it starts recording continuously for about 5
minutes. If multiple cameras detect motion, with some overlap, it
could easily end up recording for hours.

There are motion detector lighting systems that work this way. For
example, a local eco-friendly business saves electricity by not having
the parking lights on unless it first detects motion. The lights are
timed to stay on for approximately twice the time it takes to walk
across the parking lot. I think that's about 4 minutes.

Things like a
furnace, electric heater, water pressure boost pump, pool heater,
demand water heater, sump pump, etc.

Again, these would tend to operate on a regular cycle except for an
'on demand' water heater. However, the 'on demand' heater fails the
'on for one hour ' parameter.

The on demand (tankless) water heater is very erratic. However, I
will admit that it doesn't run for very long after the water is shut
off. That's probably not it.

Electric heaters are much like the HVAC system. It really depends on
what's going on in the house or office. If there's heavy traffic, the
heater will cycle erratically. If it's a stable environment, it will
cycle evenly. If someone left a window open, it will cycle at the
whim of the wind.

Water pressure booster pumps are to get the water pressure up to about
30 psi minimum. They operate much like well pumps. If there's a
demand, they run. If there's no demand for water, they don't run.

Sump pumps might be a stretch, unless they're dealing with a water
leak that is also erratic. Add sewage pumps to the list for those
with toilets below the sewer or septic level.

There are also some uncommon
devices that cycle. Negative ion generator, parking lot light
controller, external HDD or NAS boxes, motion detector operated
devices, iPhone background sync, etc.

Again, these devices fail either the '10 second' or 'one hour'
parameter.

I beg to differ. One negative ion generator I had to deal with was
purchased on eBay and apparently had never bothered to pass FCC Part
15 radiation testing. It wiped the entire HF band. Oddly, it wasn't
the ozone err.... negative ion generator part that was generating the
RFI. It was the motor that pushed the air through a HEPA filter. The
motor would run whenever the device detected motion in the room as an
energy saving feature. I think the hysteresis was about 2 minutes,
but I'm not sure. If someone was in the room, it would easily run for
an hour.

I know a bit too much about external USB HDD drives and NAS boxes from
my day job. Usually, they just sit there doing nothing. However, if
the owner has it setup to do either continuous or scheduled backups,
it will run erratically according to the program parameters. The 10
second cycles could easily be some manner of continuous backup
program, such as Memeo, which comes with WD drives. Memeo sends a
copy of any file that changes on the computah to the external drive in
short bursts, when the machine isn't busy. That takes a few seconds.
The 1 hr run could be a more complete backup, or an image backup. Same
with the NAS storage box, except over the LAN instead of USB.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558