On Thursday, April 11, 2019 at 10:10:56 AM UTC-4, Don Kuenz wrote:> Just before this issue went to press, I received a product safety > complaint via NSW Fair Trading, alleging that _Silicon Chip_ > magazine is unsafe. Apparently, this is because we explain how > to build mains-powered devices, such as the Touch & IR Remote > Control Dimmer featured in February and March this year. ... > > http://www.siliconchip.com.au/Issue/2019/April/Nannies+want+to+stop+you+building+mains-powered+projects > > A couple of years ago, the number of people in SED who apparently lack > any practical experience with full wave bridge rectifiers that plug > directly into an electrical outlet surprised me. As a teenage circuit > designer, it was only natural for me to design and build power supplies > that plugged directly into an electrical outlet. A power supply was > typically the first phase of any new design because it was needed to > power sub-circuits in order to verify my design as components were > assembled. > What happens after 120VAC becomes taboo? Do we start to take a long > hard look at +48VDC? > > Thank you, 73, > > -- > Don Kuenz KB7RPU > There was a young lady named Bright Whose speed was far faster than light; > She set out one day In a relative way And returned on the previous night.There is issue of a lifetime of PTSD treatment from just the experience of a shock.
Nannies want to stop you from building mains-powered projects
Started by ●April 11, 2019
Reply by ●April 14, 20192019-04-14
Reply by ●April 14, 20192019-04-14
On Sun, 14 Apr 2019 15:49:11 -0700 (PDT), bloggs.fredbloggs.fred@gmail.com wrote:>On Thursday, April 11, 2019 at 10:10:56 AM UTC-4, Don Kuenz wrote: >> Just before this issue went to press, I received a product safety >> complaint via NSW Fair Trading, alleging that _Silicon Chip_ >> magazine is unsafe. Apparently, this is because we explain how >> to build mains-powered devices, such as the Touch & IR Remote >> Control Dimmer featured in February and March this year. ... >> >> http://www.siliconchip.com.au/Issue/2019/April/Nannies+want+to+stop+you+building+mains-powered+projects >> >> A couple of years ago, the number of people in SED who apparently lack >> any practical experience with full wave bridge rectifiers that plug >> directly into an electrical outlet surprised me. As a teenage circuit >> designer, it was only natural for me to design and build power supplies >> that plugged directly into an electrical outlet. A power supply was >> typically the first phase of any new design because it was needed to >> power sub-circuits in order to verify my design as components were >> assembled. >> What happens after 120VAC becomes taboo? Do we start to take a long >> hard look at +48VDC? >> >> Thank you, 73, >> >> -- >> Don Kuenz KB7RPU >> There was a young lady named Bright Whose speed was far faster than light; >> She set out one day In a relative way And returned on the previous night. > >There is issue of a lifetime of PTSD treatment from just the experience of a shock.Yikes. I had one that left me shaking for a full day. -- John Larkin Highland Technology, Inc lunatic fringe electronics
Reply by ●April 14, 20192019-04-14
On Sun, 14 Apr 2019 15:49:11 -0700, bloggs.fredbloggs.fred wrote:> There is issue of a lifetime of PTSD treatment from just the experience > of a shock.Only for snowflakes, pansies and nancy-boys. Seems nearly everyone in the search for victimhood and a free hand-out claims they suffer from PTSD nowadays. -- This message may be freely reproduced without limit or charge only via the Usenet protocol. Reproduction in whole or part through other protocols, whether for profit or not, is conditional upon a charge of GBP10.00 per reproduction. Publication in this manner via non-Usenet protocols constitutes acceptance of this condition.
Reply by ●April 14, 20192019-04-14
On 14/04/2019 18:55, upsidedown@downunder.com wrote:> On Sun, 14 Apr 2019 08:01:28 -0000 (UTC), Jasen Betts > <jasen@xnet.co.nz> wrote: > >> On 2019-04-13, Cursitor Doom <curd@notformail.com> wrote: >>> On Sat, 13 Apr 2019 10:28:43 -0700, John Larkin wrote: >>> >>>> I theorized that my 1200 volt pulse generator wouldn't shock me (it >>>> makes 7 ns pulses at 5 MHz maybe) so I grabbed the output. Nothing >>>> happened. If you tease it with a fingertip, you can get a tiny RF burn. >>> >>> I get the exact same sensation from touching an exposed HDMI socket! >>> Feels like about 110V. No idea why such a voltage should be present on an >>> unshielded, exposed socket that kids could easily stick in their >>> mouths. :-/ >> >> "Y" capacitors. > > A mains filter that has an Y-capacitor is intended to be connected to > a Class I grounded socket.No, Y capacitors with the correct certifications and capacitance value may also be connected from mains to the SELV secondary circuitry and exposed metal on class II appliances. It is done to provide a return path for the high frequency current that flows in the inter-winding capacitance of SMPS transformers, to prevent some of that RF current flowing in cables and failing conducted EMC. There is a limit to how much current the Y-capacitor are allowed to deliver to the user without being "hazardous", which sets the maximum Y capacitor value that can be used in one appliance, but if you interconnect a lot of AV equipment - TV, DVD player, various set top boxes etc. then it adds up to the point where the total current is somewhat painful. Putting a screen/shield between the windings of the transformer, connected to neutral, would be a nicer way to fix it, but would cost more.
Reply by ●April 14, 20192019-04-14
On 4/14/19 12:29 PM, John Larkin wrote:> On Sun, 14 Apr 2019 08:14:44 -0700 (PDT), jurb6006@gmail.com wrote: > >>> "What's this constant obsession with race about?" >> >> I wouldn't say he is obsessed with it just because he is willing to make a little joke, or discuss the issue. > > But he talks about race more than he talks about electronic design. In > SED. > >> >> In fact I think it is more obsessive to consciously avoid the subject. > > This is SED. What he avoids is electronics. > > Actually, most of the people who post here avoid electronics. >There wasn't anything related to electronics design in this thread to begin with. it began with: "What happens after 120VAC becomes taboo? Do we start to take a long hard look at +48VDC?" that is to say rather like the thread on "Western Culture Has Died a Politically-Correct Death" I rarely see so much histrionic behavior. panicking because a magazine got ONE complaint. OMG I'm building a tube circuit right now call the police!!!!!
Reply by ●April 14, 20192019-04-14
On 4/14/19 12:29 PM, John Larkin wrote:> On Sun, 14 Apr 2019 08:14:44 -0700 (PDT), jurb6006@gmail.com wrote: > >>> "What's this constant obsession with race about?" >> >> I wouldn't say he is obsessed with it just because he is willing to make a little joke, or discuss the issue. > > But he talks about race more than he talks about electronic design. In > SED.PS: weren't you just commenting on a design thread I started hardly a week ago? are you suffering short-term memory loss? Don't make up history for the benefit of guys who never once post their own designs, bro. I do.
Reply by ●April 14, 20192019-04-14
On 4/14/19 9:56 PM, bitrex wrote:> On 4/14/19 12:29 PM, John Larkin wrote: >> On Sun, 14 Apr 2019 08:14:44 -0700 (PDT), jurb6006@gmail.com wrote: >> >>>> "What's this constant obsession with race about?" >>> >>> I wouldn't say he is obsessed with it just because he is willing to >>> make a little joke, or discuss the issue. >> >> But he talks about race more than he talks about electronic design. In >> SED. > > PS: weren't you just commenting on a design thread I started hardly a > week ago? are you suffering short-term memory loss? > > Don't make up history for the benefit of guys who never once post their > own designs, bro. I do. >Like remember that time in this thread where I suggested using optocouplers and twisted pair and then everyone else thought it was cool to suggest that <mer3bep6r9sko13tgn5uamjed2vj3bvg8r@4ax.com> like oh right maybe a 60' run of wire driving a CMOS logic gate referenced to grounds in two different buildings is gonna be a problem. I like the relay logic idea better though hey it was good enough for people in the 1920s
Reply by ●April 15, 20192019-04-15
On Mon, 15 Apr 2019 09:46:38 +1000, Chris Jones <lugnut808@spam.yahoo.com> wrote:>On 14/04/2019 18:55, upsidedown@downunder.com wrote: >> On Sun, 14 Apr 2019 08:01:28 -0000 (UTC), Jasen Betts >> <jasen@xnet.co.nz> wrote: >> >>> On 2019-04-13, Cursitor Doom <curd@notformail.com> wrote: >>>> On Sat, 13 Apr 2019 10:28:43 -0700, John Larkin wrote: >>>> >>>>> I theorized that my 1200 volt pulse generator wouldn't shock me (it >>>>> makes 7 ns pulses at 5 MHz maybe) so I grabbed the output. Nothing >>>>> happened. If you tease it with a fingertip, you can get a tiny RF burn. >>>> >>>> I get the exact same sensation from touching an exposed HDMI socket! >>>> Feels like about 110V. No idea why such a voltage should be present on an >>>> unshielded, exposed socket that kids could easily stick in their >>>> mouths. :-/ >>> >>> "Y" capacitors. >> >> A mains filter that has an Y-capacitor is intended to be connected to >> a Class I grounded socket. > >No, Y capacitors with the correct certifications and capacitance value >may also be connected from mains to the SELV secondary circuitry and >exposed metal on class II appliances.This is of course true for truly SELV (Separate Extra Low Voltage) system, However, in the OP's case this was only PELV due to the external HDMI connection. In fact a Class II device with no external connections could have 230 V live in the chassis. Think about the hundreds of millions AC/DC tube televisions in the past.>It is done to provide a return >path for the high frequency current that flows in the inter-winding >capacitance of SMPS transformers, to prevent some of that RF current >flowing in cables and failing conducted EMC. > >There is a limit to how much current the Y-capacitor are allowed to >deliver to the user without being "hazardous", which sets the maximum Y >capacitor value that can be used in one appliance, but if you >interconnect a lot of AV equipment - TV, DVD player, various set top >boxes etc. then it adds up to the point where the total current is >somewhat painful. > >Putting a screen/shield between the windings of the transformer, >connected to neutral, would be a nicer way to fix it, but would cost more.
Reply by ●April 15, 20192019-04-15
On 2019-04-14, upsidedown@downunder.com <upsidedown@downunder.com> wrote:> On Sun, 14 Apr 2019 08:01:28 -0000 (UTC), Jasen Betts ><jasen@xnet.co.nz> wrote: > >>On 2019-04-13, Cursitor Doom <curd@notformail.com> wrote: >>> On Sat, 13 Apr 2019 10:28:43 -0700, John Larkin wrote: >>> >>>> I theorized that my 1200 volt pulse generator wouldn't shock me (it >>>> makes 7 ns pulses at 5 MHz maybe) so I grabbed the output. Nothing >>>> happened. If you tease it with a fingertip, you can get a tiny RF burn. >>> >>> I get the exact same sensation from touching an exposed HDMI socket! >>> Feels like about 110V. No idea why such a voltage should be present on an >>> unshielded, exposed socket that kids could easily stick in their >>> mouths. :-/ >> >>"Y" capacitors. > > A mains filter that has an Y-capacitor is intended to be connected to > a Class I grounded socket. If it is connected to a Class 0 ungrounded > socket or incorrectly uses an ungrounded (Euro) plug, the device > internal chassis is about Vmains/2, which is then visible e.g. in > external connectors. > In case the chassis is not connected to a grounded plug/socket, the > Y-capacitor capacitance should be selected so that the leakage current > is not harmful to humans, but may destroy electronics.What's the capacitor they put between the transformer primary and secondary in ungrounded powersupplies? I thought that was also "Y" eg: https://www.infineon.com/dgdl/Infineon-ICE2QR2280G-1-Demoboard-AN-v01_01-EN.pdf?fileId=5546d4624b0b249c014bbb35f4d13948 page 8 C4, below the transformer (first rotate the page 90 degrees clockwise ) -- When I tried casting out nines I made a hash of it.
Reply by ●April 15, 20192019-04-15
On Sat, 13 Apr 2019 20:53:06 -0700, John Larkin <jjlarkin@highlandtechnology.com> wrote:>On Sat, 13 Apr 2019 23:24:52 -0400, krw@notreal.com wrote: > >>On Sat, 13 Apr 2019 15:41:22 -0700, John Larkin >><jjlarkin@highlandtechnology.com> wrote: >> >>>On Sat, 13 Apr 2019 20:12:30 -0000 (UTC), Cursitor Doom >>><curd@notformail.com> wrote: >>> >>>>On Sat, 13 Apr 2019 08:47:02 -0700, John Larkin wrote: >>>> >>>>> He enjoyed learning that trick. But I've had interns who refused to >>>>> touch a PC board that was only powered by 3.3 volts. >>>> >>>>How long did they last? >>> >>>A couple of months. Sometimes less. >> >>We tend to keep them for years, then hire the best as regular >>employees. GT does a great job with interns. > >I usually get student, summer job people. The advantage of calling >someone an intern is that you can evaluate them for three months, and >keep or not keep them, more easily than a full hire. Nobody gets >fired. We did in fact hire our last two interns after about 2 months >each. > >It shouldn't take more than a few months to figure if someone is a >keeper. If you keep them for years, and then just hire the best, a >huge bunch of resources were wasted on the others. And they do feel >fired.They're never used as "conditional hires" (though we do use contractors that way - I started as a contractor). What I mean by interns working for us for years, is that they are in the coop program and work for us for the four or five years they're in college - six months here, four months in school, or whatever. When they graduate, many get hired full time.
