Electrowarmth 12 volt mattress heater

[E350]

boywonder: Wait just one minute!!! So rather than using an inverter to change DC current to AC current, from what you said, all you would need to do is to transform our existing 12v DC current up to 120v DC current to flow through the larger more resistant wires of an 120v AC electric blanket. Right?

Maybe by using a transformer, maybe by switching your house battery bank to series for the night?

And BTW, screw the microprocessor controlled new style electric blanket controllers and go with a simple rheostat DC controller. Because if it weren't for a lifetime warranty from a company that cares, Lands' End, my home use ~$250 120v AC electric blanket would be worthless.

And what daveb previously alluded to is a possible correlation between AC current electric blankets and leukemia.

[boywonder]

Originally Posted by E350

boywonder: Wait just one minute!!! So rather than using an inverter to change DC current to AC current, from what you said, all you would need to do is to transform our existing 12v DC current up to 120v DC current to flow through the larger more resistant wires of an 120v AC electric blanket. Right?

Maybe by using a transformer, maybe by switching your house battery bank to series for the night?

Well......I woudn't want to sleep on top of 120V DC! ......and transformers only work with AC.......

[E350]

Hmmm... obviously I am lacking some fundamental knowledge here...

Now that you mention it, I think there was some discussion of possible electocution with the ~120v DC high voltage current which is used to fire the HEUI injectors in a 7.3L PSD and that disconnecting the injector wiring plug one at a time while running to check for a non-contributing cylinder was not really advisable, albeit shown on Youtube...

Note to self: Cancel the Kickstarter campaign to become a Hobby Vendor selling DC electric blankets to members of the SportsMobileForum.

[Vegasrandall]

And for you DIY types. http://www.instructables.com/id/DIY-heated-clothing/. Some of the heat controllers use a resistor to vary the temperature, this uses juice! In my motorcycle days we used a car turn signal blinker inline to make it a on-off cycle to turn the heat down without the load.(if that makes sense)

[TexGX]

Got mine in today. Will test out next weekend.

texGX

[JWA]

Originally Posted by E350

Note to self: Cancel the Kickstarter campaign to become a Hobby Vendor selling DC electric blankets to members of the SportsMobileForum.

Shucks---just when I was about to donate heavily to such things!

Since we're drifting away from the OP anyway I'd be curious from an electronics POV why a MSW source would fry microprocessors. With today's glut of these types devices its something we all need to know more about.

[JWA]

Originally Posted by E350

[Today I will continue to weld an awning frame. Miled steel .065 square tubing. I don't like how MIG welding is treating my eyes and I can't get my auto darkening variable shade Miller 9000i Titanium helmet to work right for me.........

Please be VERY careful with ANY brand auto-darkening welding shades----the potential long term effects just lately becoming better known says eye discomfort or possible eye damage is not uncommon, that the more traditional fixed shades might be better over time.

Additionally the shade number needs to be more carefully matched to your actual welding tasks---Lincoln Electric has a nice short and sweet Q&A about their line of auto-darkening shades and helmets.

BE CAREFUL with those eyes, from one who has useful vision in just one, NOT related to any welding etc.

[boywonder]

Originally Posted by JWA

Since we're drifting away from the OP anyway I'd be curious from an electronics POV why a MSW source would fry microprocessors. With today's glut of these types devices its something we all need to know more about.

Yes, great question......

[daveb]

Originally Posted by boywonder

Yes, great question......

Way out of my expertise…at least this many years since my schooling days. The fact that many have reported failures (in particular with newer electric blanket controllers) suggests something is up, well maybe. Perhaps how the AC controller, which is basically a step down power supply, has some issues with the harmonics of a MSW inverter??? There are reports of other type issues (maybe not full failures) with fluorescent lighting, some lap top dongles and radio noise using MSW inverters yet I know some members use them for these devices with no problems. I heard motors (inductive loads) have an issue with modified sine waves but I’ve never actually seen it myself. My best guess is some products (not electric motors) have better built power supplies that can tolerate a square wave. So maybe it’s just the cheap power supply used on today’s blankets can’t handle MSW’s very well.
My point is I’d rather not be the beta tester on this one. I was told that older blankets don’t have an issue with this and all I can figure is components that are used today over what was used in the past are the problem. The deal with the internet is people echo what they have heard. So even what I’ve posted (not knowing the real truth through experience) may be echoing through this forum. If it’s on the net its got to be true

Even engineers might argue over this one. Overall the way I feel is being it seems silly to invert DC to AC (factoring in the inverters losses) for a simple blanket when you can pay a little more for a DC model is why wouldn't you? I guess if the DC models preform poorly might be a reason.

BTW I bought a DC to DC power supply for my laptop because I didn't want to crank up the big inverter just to power a minimal load and I didn't want to damage an expensive laptop using a cheap MSW mini-inverter. Just cautious I guess.

[boywonder]

...A couple of first hand data points.......

I have a cheap 300W tripplite MSW inverter that I move around the vehicles as required, and it charges all of our laptops, camera batteries, etc just fine.

The Tripplite 2000W MSW inverter that we installed in the neighbors RV has powered everything fine so far....Microwave, Keurig coffee maker, etc.

Modern MSW inverters have to somewhat resemble a sine wave.....There are new very fast MOSFETs around these days that I think are driving down the cost and size of true sine wave inverters as well. If you look at some of the newer style inverters, they are smaller and less expensive than the older style tripplites, etc. If the devices are fast enough, you can just slice up your modified sine wave into smaller higher resolution slices.