Wall warts, et heat
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I find it both fascinating and nearly elementary when I read about
problems and questions about wall warts. The little packages were a surprise to me when they first appeared, and I had to buy some extra "extension outlets" to plug them into, making sure that the darn extensions had a switch on them. It didn't take long before I lost track of what was plugged into what, then I noted that too many of them generated a bit too much heat while being "on" all day. This started concerning me when I noticed some hash in a receiver that was all but inline with a computer accessory wall wart, and led to a rethink of how to address the situation better. The whole idea really made for a big warning, when the Commodore outfit introduced their "cheap little computers", and unless you unplugged their version of a wall wart, it really heated up big time! My thought was "Why set up an outside power supply to just save space, and have a half baked, undervalued little heater to do the job?". The whole mess came to a head one day in a big nearby city, when a guy "rewarded his family with a computer", plugged it in with good faith, went out to eat dinner, and came home to a burned-out apartment complex! The Fire Marshall traced the source to that wall wart, and he got sued by his neighbors for the value of their lost items, then by the apartment management. He, in turn, sued the computer company, so everyone wound up in litigation for years, all due to a dangerous design for a power supply. When I had mine "sputter" on me one day, I took time to look up and order an aftermarket replacement, and dug into the factory version. It was a solid block of epoxy fill in an otherwise fair design, but due to the lack of cooling, it had no place to put the heat from pure aluminum heat sinks, and the regulators would burn out! My solution for all of them was to make up, if not buy, a short extension cord to plug into the socket strip, and have an inline switch to turn each one off with. I've had variations on that for a long time now, and one other idea worked fairly well, too, to just wait for "after warranty", then open the little case, note where air holes needed to be drilled, then ventilate them as best I could. Some didn't get ventilated in time, and are "hanging on a sick list" until I can get time to figure out a parts replacement. The one aspect of this whole mess is that a few of them have oddball voltages coming out, to power an oddball addon for a computer or radio accessory, so it's not a case of "simply setting up a 12 vdc strip for everything and grab power from a very well made, highly regulated 12 vdc power supply". I continue to clench my teeth when I see "a neat little package that works fine, just plug the wall wart into the wall socket and enjoy the toy". That's a cheap, and somewhat dangerous way to avoid adding a bit of bulk, a far better power supply, a switch, and some ventilation to a toy or rig that someone will use for who knows how long. The other irritant is the guy who, when he was asked "How would you go green", said "If everyone would simply unplug these little things, we could save x number of $$ in fuel for the power company". Essentially, he's blaming the victim for the crime. Maybe its time for all of us to find a way around the nonsense, look over our shacks, and think "safety" from the beginning. Perhaps this would give everyone some practice in building better power supplies? Good luck, 73's Gil WA5YKK ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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I believe one powerful motivation for the outboard supply approach is
that it exempts the manufacturer from having to put the entire assembly through the various safety and regulatory processes (UL, CSA, CE, etc.). He can instead put the regulatory burden on the subcontractor who furnishes the supply. This can save LOTS of money when bringing a new electronic product to market. 73... Randy, W8FN > I continue to clench my teeth when I see "a neat little package that >works fine, just plug the wall wart into the wall socket and enjoy the >toy". That's a cheap, and somewhat dangerous way to avoid adding a bit >of bulk, a far better power supply, a switch, and some ventilation to a >toy or rig that someone will use for who knows how long. ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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Many of the ones we find in the UK emit copious amounts of RF
interference. Although they are CE marked, we suspect that this only stands for - China Export. 73 Stewart G3RXQ On Wed, 09 Dec 2009 07:01:05 -0600, Randy Farmer wrote: > I believe one powerful motivation for the outboard supply approach is > that it exempts the manufacturer from having to put the entire > assembly through the various safety and regulatory processes (UL, > CSA, CE, etc.). He can instead put the regulatory burden on the > subcontractor who furnishes the supply. This can save LOTS of money > when bringing a new electronic product to market. > > 73... > Randy, W8FN > >> I continue to clench my teeth when I see "a neat little package that >>works fine, just plug the wall wart into the wall socket and enjoy the >>toy". That's a cheap, and somewhat dangerous way to avoid adding a bit >>of bulk, a far better power supply, a switch, and some ventilation to a >>toy or rig that someone will use for who knows how long. > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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