- can't figure correct resistance for teflon coated copper wire - 13 Updates
- question about PC power supplies - 3 Updates
- swapping out K type thermocouples? - 2 Updates
| Runner <runners@aolnospam.com>: Nov 13 12:18PM -0500 > Since the resistance of copper goes up with temperature (R is ~ temperature) > controlling the voltage might be best. (no thermal runaway) > Are you using AC or DC power. 12 VDC. AC might be easier, get a transformer > (maybe filament transformer?) and drive it from a variac. I had originally considered this, but variacs in general are not isolated from the AC line and I felt I would have needed an additional isolation transformer, something I don't currently have and they seem to be quite costly. > DC will be trickier ('cause that power has to go somewhere) and some > PWM scheme might be the way to go. Or buy a variable DC supply... > you can use it for electroplating when not staying warm. :^) I am currently using the PWM controller with the DC lines to the blanket. So far so good. I have been monitoring temperature of the blanket wiring. It does get up to 180 F, but I am using a timer to cycle the system on and off so that the blanket is not running continuously. I'm not sure how much I will have to vary the duty cycle yet as the house hasn't reached its wintertime lows, but the hope is for a 33% time on and the rest off. Just have to wait and see. I'm currently using a mechanical timer, but I may switch out to a programmable one I have here. > In general I'm wondering why not try a heating pad and a nice down > comforter? I did this several years ago. No heating pad, but two stacked down duck filled comforters. I still have this set up on the bed in the other room. Took a long time to heat up, but once warm I couldn't cool down so ended up having to turn a box fan on at full blast at 3 AM in a 47 F bedroom! I suppose I could set the fan up on a timer to do this automatically, never thought of that. |
| "Peter W." <peterwieck33@gmail.com>: Nov 13 09:36AM -0800 https://www.amazon.com/long-hot-water-bottle/s?k=long+hot+water+bottle Has the ability to provide a short-term boost without the worry about duty-cycles and such. No controllers, timers or other needlessly complex devices. My wife and I like a cold room, but we temper that with the number of permitted pets on the bed. We have 180 pounds of available pets, being 95/25/20/20/20 (Golden/Scottie/Maine Coon/Main Coon/Main Coon Mix). And where the expression "Three dog night" came from. Once again, demonstrating that this venue exists to provide needlessly complex solutions to otherwise simple problems using the most obscure means-and-methods presented with the maximum amount of obfuscation using as many words as possible. Peter Wieck Melrose Park, PA |
| Three Jeeps <jjhudak4@gmail.com>: Nov 13 10:08AM -0800 On Saturday, October 31, 2020 at 12:17:38 AM UTC-4, Jeff Liebermann wrote: > 150 Felker St #D http://www.LearnByDestroying.com > Santa Cruz CA 95060 http://802.11junk.com > Skype: JeffLiebermann AE6KS 831-336-2558 Just to add a bit of information to this guidance, joining nichrome wire to nichrome or copper can be a bit of a challenge if you are not aware of the metallurgy issues. It does not solder with lead free rosin core solder. Connections to nichrome wire are often done with a crimp style connector. This may not be a workable solution for an electric blanket, depending on the area where the splice is applied. Nichrome can be soldered but you need a acid type flux and the degree of success is somewhat dependent on the type of nichrome (A: has no iron and behaves like stainless steel, B: contains some iron and can be more easily soldered). I've had good luck joining both types using Ruby fluid flux and in one case using flux for soldering copper pipe, e.g. plumbing flux. Some people have had good luck with 60/40 acid core flux but I have not tried it. My guess is that it would work better on C type nichrome. I also have used a small tack welder but its not a common household or shop tool. If you look on the web am sure you will find lots of alternatives. J |
| Three Jeeps <jjhudak4@gmail.com>: Nov 13 10:12AM -0800 On Friday, November 13, 2020 at 1:08:12 PM UTC-5, Three Jeeps wrote: > I also have used a small tack welder but its not a common household or shop tool. > If you look on the web am sure you will find lots of alternatives. > J whoops - typo - I have used 60/40 acid core with some success...(sorry, wrong sentence when doing 3 things at once...) J |
| legg <legg@nospam.magma.ca>: Nov 13 01:57PM -0500 On Fri, 13 Nov 2020 12:18:15 -0500, Runner <runners@aolnospam.com> wrote: >bedroom! I suppose I could set the fan up on a timer to do this >automatically, never thought of that. >> George H. Why not use a proper thermostat? I don't recommend electric blankets. For a multitude of reasons. Add or subtract blankets, as required. RL |
| Fox's Mercantile <jdangus@att.net>: Nov 13 02:07PM -0600 On 11/13/20 12:57 PM, legg wrote: > I don't recommend electric blankets. For a multitude > of reasons. I just bought a new one. I turn it one 20-30 minutes before I go to bed. I turn it off when I go to bed. But when I go to bed, the bed is nice and warm. Beats the shit out of laying there swearing for 15-20 minutes waiting for the bed to finally get warm. -- "I am a river to my people." Jeff-1.0 WA6FWi http:foxsmercantile.com |
| Runner <runners@aolnospam.com>: Nov 13 03:41PM -0500 On 11/13/20 3:07 PM, Fox's Mercantile wrote: > But when I go to bed, the bed is nice and warm. > Beats the shit out of laying there swearing for 15-20 > minutes waiting for the bed to finally get warm. If a Sunbeam, good luck keeping it working. I went through three in five years before finally going the DIY route. I'm not sure what's happened to them. I couldn't even get any of the ones I bought to last out the season. I think it has something to do with the current circuit they use and the blanket wiring. Growing up, my parents and I had their blankets and they lasted 15 years before I unfortunately tossed them a decade ago. |
| Runner <runners@aolnospam.com>: Nov 13 03:43PM -0500 On 11/13/20 1:57 PM, legg wrote: >> automatically, never thought of that. >>> George H. > Why not use a proper thermostat? With the blanket? Maybe, but not sure how to incorporate or what to use. |
| Fox's Mercantile <jdangus@att.net>: Nov 13 08:05PM -0600 On 11/13/20 2:41 PM, Runner wrote: > they use and the blanket wiring. Growing up, my parents and I had their > blankets and they lasted 15 years before I unfortunately tossed them a > decade ago. My previous one was a Sunbeam, it went tits up after three years. The new one is a Biddeford. Unlike the Subeam, it's soft and fuzzy. -- "I am a river to my people." Jeff-1.0 WA6FWi http:foxsmercantile.com |
| Runner <runners@aolnospam.com>: Nov 13 09:16PM -0500 On 11/13/20 9:05 PM, Fox's Mercantile wrote: >> tossed them a decade ago. > My previous one was a Sunbeam, it went tits up after three years. > The new one is a Biddeford. Unlike the Subeam, it's soft and fuzzy. I didn't have much luck with Biddeford either. I tried one of their heated mattress pads. It didn't last a season. Hopefully, you'll have better luck with their blankets. |
| Runner <runners@aolnospam.com>: Nov 13 09:31PM -0500 On 11/13/20 1:12 PM, Three Jeeps wrote: >> J > whoops - typo - I have used 60/40 acid core with some success...(sorry, wrong sentence when doing 3 things at once...) > J I never did go with the nichrome wire. I have some, but used it three years ago to make some telescope dew heaters. The idea was to wrap the front of the telescope with nichrome embedded in a fabric with just enough wattage to keep dew away. Works great at 5 to 10 watts. For that I believe I crimped it to the supply wires. When I started on the blanket, there was no way I was going to try using nichrome for something that large and went with some 22 ga Teflon coated wire I had around for years. So far, it has been working out well. I can get up to 80 watts, but I will mostly be running at half that or a little over as there's much less heating to deal with. Today, the dimmer arrived and I tried out a jacket I also wired. It too reaches 80 watts but again I will only need about 50. 80 watts seems a bit too much even in a cold house. Initially, to hold the Teflon wiring in place, I used hot glue. However, when 80 watts passed through, some of it began to not only outgas but melt so I removed all of it and went with nylon ties. I first tested the nylon and a bit of blanket fabric by heating in the oven at 90 C for several hours and both came out fine. I was a bit concerned as nylon seems advertised to hold well up to like 85 C, but I don't see any issues. Only other issue was temperature. The longer the blanket is on at the max, the warmer it slowly creeps up. So, I have to either run it at less power, which I will normally do, or have a duty cycle using a timer. I have since incorporated a timer for when it gets colder in here. I'm going to try for a 33% time on and 2/3 time off and see how it goes. Someone has suggested a thermostat, but not sure how other than maybe using a probe attached to the blanket wires and then a relay turns the blanket on and off as needed. |
| "ohg...@gmail.com" <ohger1s@gmail.com>: Nov 14 03:47AM -0800 On Friday, November 13, 2020 at 3:41:19 PM UTC-5, Runner wrote: > they use and the blanket wiring. Growing up, my parents and I had their > blankets and they lasted 15 years before I unfortunately tossed them a > decade ago. Sunbeam blankets don't flat out quit, they slowly get colder over time. Not sure why that is. It's like they're programmed to do so. Too bad because their controllers are great. I switched to their mattress pads and they get inert over two or three seasons. Looking for another option right now. |
| Runner <runners@aolnospam.com>: Nov 14 10:57AM -0500 >> blankets and they lasted 15 years before I unfortunately tossed them a >> decade ago. > Sunbeam blankets don't flat out quit, they slowly get colder over time. Not sure why that is. It's like they're programmed to do so. Too bad because their controllers are great. I switched to their mattress pads and they get inert over two or three seasons. Looking for another option right now. Exactly right, don't just quit but lose warmth over time. Out of the three Sunbeam blankets I owned and two heated throws, they all did this. This was my main inspiration for my DIY revamping. There's actually a fair amount of online info on the Sunbeams if you do a patent number search. A circuit block will come up along with at least one schematic. I thought the culprit might have been a small SMD voltage sampling transistor inside the little box where the cord plugs into the blanket, but replaced that and still no heating. I also swapped out controllers for a different one to no avail. So, that left the blanket itself. I suspect the changing of wire resistance from repeated heating is what does it and of course there's no solution without either a revamping as I have done, or a new blanket. Patent numbers show that someone definitely designed their latest circuitry. IMHO, probably due to lawsuits and other worries from the past, it was overdesigned and thus now stops working after short order. There is no easy solution unless one wants to try other brands and take a chance that you might come across one that actually keeps working. |
| legg <legg@nospam.magma.ca>: Nov 13 01:49PM -0500 >of current indicated per voltage be used simultaneously (in other words, >can I use say 12V @ 13A & 5V @ 19A at the same time) or are the maximum >(or near max) currents available for one voltage only at a time? For UL or CSA safety rated power supplies, the combined output powers shouldn't exceed the continuous output power rating of the product, as written on the label carrying the certification marking. The unit is safety tested with any/all combination of continuous output channel powers that can occur below the total power rating for the unit. Individual outputs are good for their labelled C x V rating. If there is a special pulsed limit for an output, it should be documented on it's spec sheet, but this need not show up on labelling. A minimum load condition may be specified to maintain the expected regulated output voltage. You'll get longer life out of the unit if you keep a derating on average loads, keep design air flow levels unrestricted and minimize the number of times the input power is cycled. RL |
| Jeff Liebermann <jeffl@cruzio.com>: Nov 13 06:01PM -0800 >powers shouldn't exceed the continuous output power rating of >the product, as written on the label carrying the certification >marking. Yep. >The unit is safety tested with any/all combination of continuous >output channel powers that can occur below the total power rating >for the unit. Yes, but not any/all combination, but rather whatever the manufacturer declares to be safe. For example, if the power supply shares the +5V and +3.3V circuitry, the maximum total power will be whatever the circuit can handle. Example of such a nightmare specification: <https://hardwareinsights.com/wp/wp-content/uploads/2013/02/PSI-Label.jpg> The +5V and +3.3V share quite a bit of circuitry. The labels says that the total simultaneous dissipation for the two sections is 130 watts. Yet, if I calculate the maximum for each section, I get: 3.3V * 22A = 72.6W 5V * 16A = 80.0W ============== Total = 153W which is more than the rated 130 watts. Same with the other sections on the chart. If I add together all the outputs: 3.3V * 22A = 72.6W 5V * 16A = 80.0W 12V1 * 15A = 180W 12V2 * 16A = 192W -12V * 0.8A = 9.6W 5VSB * 2.5A = 12.5W =============== Total = 547W which is more than the rated total output of 500 watts. -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
| legg <legg@nospam.magma.ca>: Nov 14 08:19AM -0500 On Fri, 13 Nov 2020 18:01:43 -0800, Jeff Liebermann <jeffl@cruzio.com> wrote: > =============== > Total = 547W >which is more than the rated total output of 500 watts. Where the label specifically gives grouped power ratings, they should be followed. The same goes with any other grouped rating, including the rating for the full power supply, 500W. Users are seldom provided with such detailed ratings info on the actual label, suggesting that this unit is marketed as a stand-alone product for evaluation/use by lower-volume end-user/developers. Safety testing will have evaluated those ratings as listed on the label, under any worse-case shift of load. It can be time consuming to do so, but may reduce the actual part cost to the mfr, in the long run. Too much information often indicates a not-very-rugged design, but in cost-critical markets, this is seldom a deciding factor. RL |
| "Peter W." <peterwieck33@gmail.com>: Nov 13 08:55AM -0800 > Can this longer > thermocouple's ends be cut off and be replaced with the same type of U > interface that the current one uses? Short answer is Yes, they *can* be cut off. More on this later. It seems like a lot of work for a dubious outcome. But first: Verify that the extended TC device will provide accurate information to that device. This is not certain. And also: Unless the entire environment is under difficult conditions, what about using conventional wire to extend the shorter probe? Again, verify that such an extension will still allow accurate information to get to the device. And, lastly, why not adapt to that plug. Use a couple of appropriately sized insulated push-on connectors to short spade-lugged jumpers. This being after you verify that it provides accurate information. Even better, if the spacing is correct, use crimp-on spade lugs directly onto the plug tines. Remember, this venue exists in order to provide the most difficult and complex solutions to otherwise simple problems in the most obscure and irretrievably awkward way. Peter Wieck Melrose Park, PA |
| Phil Allison <pallison49@gmail.com>: Nov 13 06:30PM -0800 ABC_D wrote: ================ > The problem is that the connecting leads don't match. Can this longer > thermocouple's ends be cut off and be replaced with the same type of U > interface that the current one uses? Thank you. ** Buy a K type socket and use that. https://au.element14.com/labfacility/am-k-ff/socket-k-ansi-mini-fascia/dp/2347130 Anything else will introduce errors due to contact potential effects ...... Phil |
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