Electric blankets, Gratuitous complexity??

[mike]

snipped righteous rants etc...

Products are designed to produce the best perceived value by the most
customers...mitigated by applicable safety regulations.

People who like to sleep in their truck are not the target demographic
and never will be.
If you expect to sleep "outside the box", you need to pick your
electric blankets more carefully. Ranting won't help.

 

[Adrian Tuddenham]

Or, just put a small transformer on the affected device.

....or buy another blanket that is better designed.

 

[Jasen Betts]

I noticed the same thing during the recent power failure..

The electronically controlled electric blanket will not run on my
modified sine inverter.

I think the third wire might be connected to a thermistor or
temperature sensor in the blanket that the controller uses.

it could just be a shield, an scr-controlled electric blanket would
otherwise radiate EMI something fierce.

If you don't mind wrecking the controller, you could wire the heater
directly to the plug and use it on high... or wire in a switch with a
diode and have full and 1/2. That would also defeat the timer
function. Also beware this also might disable the overheat safety
feature.

it would probably be bad for the inverter too.

I'm thinking about designing a filter that will round off the modified
sine enough so that the blanket can work with the inverter.

an off-the-shelf line filter might do that.

 

[whoyakidding]

My hot-wired blanket now works, and as far as the risk of fire goes, even at
full blast, it's got a long long way to go before ignition... heh, famous
last words, eh?? LOL

It sounds like you're on a parallel path to what I have in my
motorhome. It had 2 tired deep cycle batteries which I replaced and
added a third. If I remember right I have about 1kwh capacity to 50%.
I bought a 1000W true sine inverter on sale for $150. Now I have more
battery capacity for running the furnace heavily overnight when dry
camping in cold temperatures. And I don't have to use the generator
nearly so often. Even the inverter microwave is OK at half power.

In my rig the bedroom is at the back. It stays cool when the rest of
the coach is toasty. I've considered getting an electric blanket and
running it off the inverter and then turning down the furnace
thermostat overnight. I should break even on the battery use and come
out ahead on propane. One wrinkle is that the furnace has an outlet
into the holding tank compartment. If I run the furnace too little in
below freezing temperatures then I'd have to worry about the dump
valves freezing. I've traveled in the off season and my record so far
for being comfortable is 14 degrees Fahrenheit. Man the RV crowd
really thins out when it gets cold. If I get a chance to
experiment further I'll report here.

 

[tm]

Oh, and yes -- I know about those controllers that do switch only at the
zero-crossings, but then count cycles to accomplish duty cycle control.

Those are even more "gratuitously complex" than the others, but perhaps
they've gotten that sort of control down into the $0.80USD range. That's
about the price it would have to be to find its way into a consumer
electric blanket.

LLoyd

A cheap pic could easily do that. It used to be a bi-metallic thermo
switch.

 

[Jim Wilkins]

...
The small standby UPS does no wave shaping when allowing the load to
run on "line " voltage - and most are, at best, modified sine wave
output.

A UPS "modified sine wave" is a sequence of positive and negative
square pulses at 160 to 170V, with enough off time between them to
reduce the average (RMS?) voltage to 120V. I've seen the pulse width
increase at higher loads that pulled down the peak voltage.

An APC Smart-Ups has a pure sine output on battery.
https://www.apc.com/products/family/index.cfm?id=165

Some of them can run off large external batteries without overheating.
Check the surplus stores for used ones. The downloadable manual shows
the simple but not obvious way to remove the old batteries.

I just discovered that the sensor-logging feature of HWiNFO32 v4.06
freeware can record the run time of an unattended laptop on its
battery, It captures the battery voltage, the power drain and the
estimated percent of remaining capacity, which will show a sudden drop
to empty if the battery's microcontroller IC needs to recalibrate
itself with a full discharge cycle.
http://www.hwinfo.com/

I use recording TV and displaying Internet weather radar as
representative high and moderate power applications to check UPS run
time. During an outage I wouldn't let it run idle on precious battery
power though that's the easiest measurement to make. The Event Log
will capture shutdown time.

I haven't tried yet, but it should also show when the UPS or inverter
powering the laptop plus your test load shuts off and the laptop
switches to internal battery.

 

[Jim Wilkins]

That Bethany VOA site is now a stinking golf course.

It went the way of the American values it promoted.

 

[[email protected]]

I didn't know thtey had such things, but
http://www.amazon.com/Heated-Fleece-Travel-Electric-Blanket/dp/B000V8QVX6
http://www.walmart.com/ip/Maxsa-Comfy-Cruise-12-Volt-Electric-Blanket-Navy-Blue/10756183

Onlly 25 dollars for each.


They let babies drive trucks!

He turned 45 a couple weeks after the crash

Glad he's doing so well

Yea, he's only got less than 30 degrees total lateral movement, and
by the end od a day his neck is sore - but with convex mirrors on the
truck he's OK as long as he's carefull. Guess they figured it was
better to let him drive again than to try to retrain him for something
else.
Darn good driver. Other than being struck by lighning, a herd of
antelope, and about a hundred separate deer his record was very good
till he ditched and barrel rolled just west of Calgary 2 years ago May
24. Not sure how many million miles he and his little dog CB have
under thair belt - CB is 16 now and was on the road with him from the
time he was a pup antill about 6 months before the accident. (Jack
Russel /???? cross)

 

[[email protected]]

It's best when they switch on the zero crossings.

Which means either full on, half on, or off.

 

[legg]

OK.....

So ahm happier'n'a alcoholic workin the night shift in a Jack Daniels
distillery.... with my 400# deep cycle battery, 1500 W inverter (sitting
in the back seat of m'truck), and my brand new blue electric
blankey-poo.....
Now I can curl up in a fetal position -- in m'truck -- in compleat toasty
comfort.....

Now, don't ax me WHY I gotta curl up in a fetal position -- in m'truck.
Just suffice it to say, if you had my yob, you'd be curling up in a fetal
position in YOUR truck, too.

Your job? Your truck? Your blanket?

Luxury.

RL

 

[[email protected]]

[email protected] fired this volley in


Have you recently priced GTO triacs and SCRs? You won't find a turn-off
style controller at consumer prices.

LLoyd

In residential lighting dimmers, Lutron turn-off dimmers are about
double the cost of the turn-on type - which is still reasonable.

 

[[email protected]]

A UPS "modified sine wave" is a sequence of positive and negative
square pulses at 160 to 170V, with enough off time between them to
reduce the average (RMS?) voltage to 120V. I've seen the pulse width
increase at higher loads that pulled down the peak voltage.

An APC Smart-Ups has a pure sine output on battery.
https://www.apc.com/products/family/index.cfm?id=165

But a SmartUPS is not a standby - a Back-UPS is.

Some of them can run off large external batteries without overheating.
Check the surplus stores for used ones. The downloadable manual shows
the simple but not obvious way to remove the old batteries.

That is not a "small standby UPS" by anyone's definition. It is an
online UPS - AKA dual conversion.

 

[Ken S. Tucker]

It should have been turned into a museum. That site had a huge impact
on W.W. II It went from an empty pasture, to the most up to date Short
Wave Radio transmitter site in a very short period. It fed news & music
to the world, and was a huge boost to morale.

Switched wires radiate as per &E/&t (Maxwell's Eqns).
It's called sparks, and can nearly radiate all over the
radio+ spectrum.
Ken
PS: Wife & daughter used electric sheets prior to bed time.

 

[The Daring Dufas]

Wouldn't that depend on your definition of "low frequency"? My AM radio
is low frequency

My frequency of urination is high. ^_^

TDD

 

[tm]

Which means either full on, half on, or off.

So? You don't need a per cycle control. On-off every minute would be fine.
Or % of a minute.

 

[tm]

My frequency of urination is high. ^_^

TDD

You must be drinking Bud.

 

[The Daring Dufas]

You must be drinking Bud.

I've actually never consumed an alcoholic beverage in my life. I've
never had a beer, a shot of whiskey or even a glass of wine. Most
folks call me a liar but those who know me personally know my lack
of a taste for alcohol is true and that it has nothing to do with
religion. One of my blood pressure meds causes me to pee like Niagara
Falls. Plus, the caffeine in Diet Dew puts kidneys into overdrive. A
feller has to watch his figure, that's why I drink diet soft drinks. ^_^

TDD

 

[The Daring Dufas]

But it has a very short wavelength! ;-)

I've never been ashamed of my 1/4 wave whip. ^_^

TDD

 

[The Daring Dufas]

You said it was a folded dipole! ;-)

Well, there is that Slinky antenna. ^_^

TDD

 

[The Daring Dufas]

New Slinkies are plastic.

Some idiot probably got itself electrocuted with a metal one.

TDD