Running electric blanket on DC?

Meh. Take it apart, look like you're doing something, then put it back together as it was. As long as she knows you did something, but not exactly what, she'll buy it.

Tim

-- "I've got more trophies than Wayne Gretsky and the Pope combined!" - Homer Simpson Website @

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It could be done but I wouldnt recommend it. The thermostat switch would likely fail quickly and start a fire as it is much harder to interrupt DC. What you would be doing is trading an insignificant (if present) hazard for a much greater one. Much safer to leave it alone.

I suggest that you direct your wife to John Moulder's site.

together as it was. As long as she >knows you did something, but not exactly what, she'll >buy it. Tim

Perception is reality!

Mike

I recall reading some years ago that in response to the alleged problem, manufacturers were rearranging the heating wire routing inside the blanket to largely cancel the fields. I believe the new wiring is just one big "hairpin" that is then routed around the blanket. There is no loop to be inside of.

I might add that the original studies on the "problem" were of ridiculously poor quality, both on statistical and logical grounds. They probably would have never gone anywhere except that a reporter wrote up a big scare-mongering story in the New Yorker, and suddenly eveybody figured this was a real problem. Things like this can easily happen in a scientifically illiterate society.

Just my 2 cents' worth!

Bob Masta dqatechATdaqartaDOTcom D A Q A R T A Data AcQuisition And Real-Time Analysis

Yeah, I know the study was crap. But my wife prefers to believe the hype. Cheers, Eric R Snow

Does the blanket generate a strong EM field? WHy not find out?

If you hook a coil to the input of an audio amp, then listen to the amplified output using headphones, you can easily hear the 60Hz magnetism detected by the coil. For instance, wave the coil around an AC wall clock motor, or around an old-style (non-electronic) fluorescent light ballast. BUZZZZZZ! Once you can detect strong AC magnetic fields, wave your coil around the electric blanket and see if it's stronger than, say, standing under a fluorescent ceiling light.

Here's a great little $12 amp. All hobbyists should have one of these (I have several. They have lots of uses.) :

Mini audio amplifier w/speaker, 9V

That, a couple of mini-jacks, and a telephone pickup coil, and you're ready to scan the environment for those lethal 60Hz hums.

Telephone pickup coil

When I did this years ago at home, I discovered that the whole house was full of 60Hz b-fields. It was wired with old-style knob-and-tube wireing, where all of the conductors are several feet apart, rather than being twisted together inside a steel pipe.

((((((((((((((((((((((( ( ( (o) ) ) ))))))))))))))))))))))) William J. Beaty Research Engineer snipped-for-privacy@chem.washington.edu UW Chem Dept, Bagley Hall RM74 snipped-for-privacy@eskimo.com Box 351700, Seattle, WA 98195-1700 ph206-543-6195 http//staff.washington.edu/wbeaty/

Be a hero & convert it :)

Just a FWB (no cap) & its DC - _definitely_ not AC anymore!

Valid data snipped...

She wants you to convert it to run on DC? Put your full wave bridge in the circuit. Presto - its DC - Yes its unfiltered DC but it _is not_ AC anymore! I don't know of any studies that have shown low levels of pulsating DC causing any problems :)

Thermostat shouldn't be stressed because of the pulsating nature of the current - heat output should be the same - the neon light may be somewhat dimmer (only if FWB is between AC cord & controller) because just one side is flashing - that will prove its running on DC.

Depending on how much room there is in the control box & the wiring arrangement, the preferred place for the bridge would be where the actual heater connects to the controller - the thermostat & neon would still be conducting AC but the heating element is running on DC. If that is difficult (maybe because of the small wires?) - Second best (but still very acceptable) would be at the AC input (cord) side.

Please think "Safety" when working with AC mains.

Everyone comes out a winner :)

Kim

Don Kelly schrieb:

I agree and would like to mention a further problem: If you just rectify (without filtering by a condenser) you get the same heat, but you still have a lot of alternating current (and field). If you filter to get pure DC, you need a very large condenser and ir will give the peak voltage (165v for 117V AC) and the blanket will overheat..... Greetings R.Z.

Good idea! wimmin will buy anything. it's not a good idea to convert hte blanket to dc, anyway. All the time its running on AC, there's an even distribuion of blood cells in your body. If you change to DC, all you blood cells will either get drawn to your head or your feet depending on which way around the polarity is. ;-)

--Getcher self a couple of warm doggies; works wonders, heh.

-- "Steamboat Ed" Haas : Whatever happened Hacking the Trailing Edge! : to Ethyl Meatplow?

Greetings William, Thanks for the link to the amp and the ideas to use it. I can already think of other uses for it. Eric R Snow

Perfect answer Rich! I'll just say that the engineers on line have conducted a study and found that ac is actually good for you as it keeps the blood evenly distributed. Eric