Just to hijack things slightly, regarding the 'Designed to Fail' aspect. We have had a number of electric blankets over the years and they all seem to last about 3 years and then die. In all cases it has been the controller that dies although the problem is presented as a blanket failure. We swap the controllers side-side and all is well again (I don't use mine, my wife uses her side only). Then next time we buy a replacement controller set. Except that after 5-6 years replacement controllers are no longer available anywhere. I've taken a number of the controllers apart but been unable to figure out the faulty part. The more expensive ones appear to have 2 PICs or similar in them, one driving the display. The cheaper units have just one. The firmware in the PICs appears to be protected against downloading & examination. It's quite possible that there's a count-down timer involved in the firmware. The only other component that is possibly involved is the neon indicator lamp. it seems to be being used as a voltage reference of some sort. As they age they get dimmer and may be it's having an effect. Manufacturers data is useless and the patents involved are so tangled the actual detail is hidden and may refer to a different idea / product anyway. Even the most expensive, all singing/dancing LCD display units have a neon indicator that has a line going to a voltage divider and then to the micro. IIRC last time we had two controllers replaced under warranty as they were still just inside the period, then bought 2 more for about $120 each. Then, next time they were just not to be found. So far I think we've had about 8 controllers 'fail' - including the cheaper ones (same brand) on my daughters bed. All after about 3-4 years of use, and all with no problem / difference to be found in the blanket itself= .. We now have a heat pump in the bedroom & my daughter has moved out so the blankets get a lot less use and I'm not as worried about it. But it seems a complete waste to have to throw out a completely 'good' blanket because of designed-in failure & irreplaceable parts. If I had my way we wouldn't buy that brand (Sunbeam) again but the selection is limited by the 'requirements' and I get little say in that part of the process. Oh yes, last time it happened, about a year ago, we couldn't find a blanket with all the features we wanted anyway - timed switchon being the main requirement. Apparently UL have decided that that mode is unsafe unless you use an external timer. rant over (for now). RP On Fri, 30 Nov 2018 at 06:05, John Gardner wrote: > The "Electric Blanket Institute" also reports that other > > brands made by Beddeford include Sealey, Cannon, > > and Delightful Nights... > > On 11/29/18, John Gardner wrote: > > According to Boodle, Biddeford products are "now made in China". > > > > What a surprise. > > > > Perhaps factory "value re-engineering" is a factor in the failure? > > > > ... > > > > > > On 11/29/18, Art wrote: > >> I think you're so right Alan, > >> > >> The blanket has 3 loops of wire over the entire surface of the queen > >> size version, so there is about one wire every foot or so. If there we= re > >> more feet of wire per each blanket, the power density would be much > >> improved and the surface temperature of the insulation would be lower. > >> So, for the same amount of power from the outlet, any wires pressed > >> against each other from 'bunching' would be much less prone to failure > >> by melting. > >> > >> Now, add in teflon or similar higher melting point insulation, and the > >> problem would probably be nonexistent and there would be no need for a= ny > >> failsafe spiral copper wire wrap. > >> > >> I am very upset to hear that low temperature melting insulation was us= ed > >> INTENTIONALLY! > >> > >> BTW, the company rep had no idea why the copper spiral winding was not > >> connected inside the blanket. I'm wondering now if it was a Chinese > >> fake??? It was purchased through JC Penny however. > >> > >> I wish I wasn't so anxious to throw the remains in the trash!!! It was > >> trash day however, the bedding had burned and there was no need to kee= p > >> it. So, after the autopsy, everything went into the trash! Damn, I wis= h > >> I had kept the remains::> > >> > >> In fairness to Biddeford, their rep offered to replace my mattress and > >> the damaged bedding, even though this was a 5 to 7 year old blanket. I > >> declined his offer, but I did accept the replacement blanket he offere= d. > >> > >> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D > >> > >> Just between you and me, I'm tempted to dissect the blanket Biddeford > >> sends and then rebuild it with some larger gauge teflon insulated > >> stranded copper wire...using more wire loops, but running it on 3 to 1= 2 > >> volts (or even lower). There would be no failsafe protection, but it > >> probably isn't needed anyway IF the blanket has more feet of wire with= in > >> the blanket itself. To demonstrate that no failsafe protection is > >> needed, I'd roll the thing into a ball and leave it operating. I think > >> it would be much safer. > >> > >> I think I'd have a PIC monitoring the current draw constantly, so any > >> shorting out of the conductors within the blanket would be detected > >> immediately. There would be no need for the failsafe spiral wrap > winding. > >> > >> I'm not sure if a heating element can be made from copper however. Tod= ay > >> we can make highly efficient power supplies at low voltage, *so maybe > >> copper wire can be used as a heating element. Comments on the heating > >> wire heating element would be appreciated.* > >> > >> Regards, > >> > >> Art > >> > >> > >> ....meaning the insulation On 11/29/18 9:40 AM, AB Pearce - UKRI STFC > >> wrote: > >>>> Mind you: that didn't stop a faulty washing machine from starting t= he > >>>> tragic fire in Grenfell Towers. > >>> And the ongoing evidence seems to suggest that the cost cutting of > >>> appliance manufacturers is causing rather too many fires in homes, > >>> sadly. > >>> > >>> > >>> > >> > >> -- > >> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > >> View/change your membership options at > >> http://mailman.mit.edu/mailman/listinfo/piclist > >> > > > > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > -- http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .