On a sunny day (Sun, 30 Nov 2014 12:30:34 +1100) it happened Clifford Heath <no.spam@please.net> wrote in <Wmuew.496643$Lq6.215328@fx29.iad>:>2nF requires 80MHz to reach 1 ohm. Are you sure you want a kilowatt of >80MHz just to save on magnetics?Dunno what they use it for, but they will get serious RF burns if they think it is 'isolated'.
Galvanic isolation without transformers ??
Started by ●November 27, 2014
Reply by ●November 30, 20142014-11-30
Reply by ●November 30, 20142014-11-30
Den s=C3=B8ndag den 30. november 2014 02.23.09 UTC+1 skrev rickman:> On 11/29/2014 11:13 AM, Lasse Langwadt Christensen wrote: > > Den l=C3=B8rdag den 29. november 2014 16.29.25 UTC+1 skrev rickman: > >> On 11/29/2014 10:11 AM, meow2222@care2.com wrote: > >>> On Saturday, November 29, 2014 2:31:07 PM UTC, rickman wrote: > >>>> On 11/29/2014 9:04 AM, meow2222@care2.com wrote: > >>>>> On Saturday, November 29, 2014 7:41:59 AM UTC, John Fields wrote: > >>>>>> On Fri, 28 Nov 2014 03:00:12 -0800 (PST), meow2222@care2.com wrote=:> >>>>>>> On Friday, November 28, 2014 9:26:13 AM UTC, John Fields wrote: > >>>>>>>> On Thu, 27 Nov 2014 20:57:10 -0800 (PST), dakupoto@gmail.com wro=te:> >>>>>>>>> On Thursday, November 27, 2014 12:45:53 PM UTC-5, John Fields w=rote:> >>>>>>>>>> On Wed, 26 Nov 2014 21:21:58 -0800 (PST), dakupoto@gmail.com w=rote:> >>>>> > >>>>> > >>>>>>>> For example, consider 120 volt 60Hz mains being used to drive a > >>>>>>>> 12V/12mA load through two capacitors for "perfect" isolation fro=m> >>>>>>>> both sides of the mains: > >>>>>>>> > >>>>>>>> C1 > >>>>>>>> 120L>-----[CAP]----+ > >>>>>>>> |R1 > >>>>>>>> [1000R] > >>>>>>>> C2 | > >>>>>>>> 120N>-----[CAP]----+ > >>>>>>>> > >>>>>>>> FIG 1. > >>>>>>>> > >>>>>>>> In order to make life easier, though, we can combine C1 and C2 -=for> >>>>>>>> now - and have our circuit look like this: > >>>>>>>> > >>>>>>>> E1 E2 > >>>>>>>> / C1 / > >>>>>>>> 120L>-----[CAP]----+ > >>>>>>>> |R1 > >>>>>>>> [1000R] > >>>>>>>> <--I1--> | > >>>>>>>> 120N>--------------+ > >>>>>>>> > >>>>>>>> FIG 2. > >>>>> > >>>>>>>> Finally, to return to the configuration in figure 1, the capacit=ors> >>>>>>>> are equal-valued and in series, so the value of each must be twi=ce> >>>>>>>> the value of the single cap shown in figure 2, or 534nF each. > >>>>>>>> > >>>>>>>> That's about half a microfarad each for a 12mA load, so if the l=oad> >>>>>>>> goes to 120mA the caps go to about 5.5=E6=B9=A9 each, and to abo=ut 55=E6=B9=A9> >>>>>>>> each for a 1200mA load. > >>>>>>>> > >>>>>>>> Because of that and because of the safety issues surrounding usi=ng> >>>>>>>> caps for off-line voltage droppers, transformers start looking > >>>>>>>> better than caps somewhere between three and ten VA, I'd guess, =with> >>>>>>>> anything notmuch higher than that being no contest. > >>>>> > >>>>>>> The C in your circuit acts like a dropper or ballast, it doesn't =give full isolation. Touch the load and you can still get a shock. Cs on bo= th L&N give a load floating at half mains V, ground the load and i doubles.> >>>>> > >>>>>> I disagree in that the shock can only occur if the toucher isn't > >>>>>> floating, and since the capacitors' dielectric provides the > >>>>>> insulation to prevent ohmic contact between the load and either si=de> >>>>>> of the mains, the load is, by definition, isolated. > >>>>> > >>>>> Lets be clear here. Capacitors pass current at 110/230v ac. How muc=h current depends on the capacitance. A cap that passed 1A to a load would = also pass about 1A to a human, frying them. Its only safe when, among other= things, the cap is small enough to limit current to a touch-safe value.> >>>>> > >>>>> > >>>>>> In addition, the OP's: > >>>>>> > >>>>>> "Indeed, it is very much possible to provide galvanic isolation wi=th> >>>>>> capacitors for AC, and in fact, capacitive reactance may be used t=o> >>>>>> reduce high mains side current(5A) on manageable isolated load sid=e,> >>>>>> as well." > >>>>>> > >>>>>> seems to indicate interest in situations where the load will be > >>>>>> floating, so even a single-capacitor solution should work for him. > >>>>> > >>>>> Single caps work ok for the load, but leave a potential toucher tou=ching the mains directly.> >>>>> > >>>>> > >>>>>>> I've long thought that CR droppers would make the basis of good p=ower supplies for sub-mA [touchable] loads, and could be allowed quite safe= ly..> >>>>> > >>>>>> I'd only ever advocate the use of a reactively controlled supply i=f> >>>>>> it was used in a double-insulated device. > >>>>> > >>>>> If the caps are suitably rated and sized, and you have sufficient c=urrent control for safety from either C or R in the psu, you get something = needing multiple failures for any risk to occur, which is perfectly satisfa= ctory safety-wise. At that point there is no need for any insulation from t= he user.> >>>> > >>>> I've always wondered about the wisdom of the "multiple" failure meth=od> >>>> to minimize risk. Like "double insulated" hand tools, vs. grounded > >>>> devices. If one layer of the insulation fails you are not exposed t=o a> >>>> shock. But at that point the tool is only "single insulated" and th=e> >>>> low risk has just become much higher. If there is no way to determi=ne> >>>> that one of the two protections has failed, there can potentially be > >>>> many devices running around that are just one failure away from an > >>>> accident. > >>> > >>> There are. Its a big improvement. > >> > >> There are what? What is a big improvement? > >> > >> > >>>> Potentially, again if there is no way to verify the proper functioni=ng> >>>> of each layer of protection, such a device could have been manufactu=red> >>>> with one layer of protection defective. > >>> > >>> Plenty of those about. > >> > >> I'm not convinced we weren't a lot better with mandatory grounds on al=l> >> hand held power tools.... other than the battery powered ones of cours=e,> >> lol. > >> > > > > Around here very little is grounded, most sockets and plugs don't even =have> > ground. ground fault interrupter is mandatory > > > > The biggest problem is that it puts the chassis of most things with swi=tching supplies at 120V via the Y capacitors> > It'll give you good jolt if you touch something grounded and a computer=,> > plenty of inputs have been killed by plugging an ungrounded computer in=to a TV> > grounded via the antenna cable >=20 > I have no idea what you are talking about. I guess you aren't in the=20 > US. Here outlets have ground by law.correct, I'm in Denmark>=20 > Hot chassis have not be used here in over 50 years! >=20The chassis is not hot, but the capacitive divider formed by the input filt= er puts the chassis at half the mains voltage, very low current but still e= nough to give you a buzz or kill an IC input http://www.murata.com.sg/Portal/ASEANWeb.nsf/dx/faq8.jpg/$file/faq8.jpg -Lasse -Lasse
Reply by ●November 30, 20142014-11-30
On Sat, 29 Nov 2014 06:04:39 -0800 (PST), meow2222@care2.com wrote:>On Saturday, November 29, 2014 7:41:59 AM UTC, John Fields wrote: >> On Fri, 28 Nov 2014 03:00:12 -0800 (PST), meow2222@care2.com wrote: >> >On Friday, November 28, 2014 9:26:13 AM UTC, John Fields wrote: >> >> On Thu, 27 Nov 2014 20:57:10 -0800 (PST), dakupoto@gmail.com wrote: >> >> >On Thursday, November 27, 2014 12:45:53 PM UTC-5, John Fields wrote: >> >> >> On Wed, 26 Nov 2014 21:21:58 -0800 (PST), dakupoto@gmail.com wrote: > > >> >> For example, consider 120 volt 60Hz mains being used to drive a >> >> 12V/12mA load through two capacitors for "perfect" isolation from >> >> both sides of the mains: >> >> >> >> C1 >> >> 120L>-----[CAP]----+ >> >> |R1 >> >> [1000R] >> >> C2 | >> >> 120N>-----[CAP]----+ >> >> >> >> FIG 1. >> >> >> >> In order to make life easier, though, we can combine C1 and C2 -for >> >> now - and have our circuit look like this: >> >> >> >> E1 E2 >> >> / C1 / >> >> 120L>-----[CAP]----+ >> >> |R1 >> >> [1000R] >> >> <--I1--> | >> >> 120N>--------------+ >> >> >> >> FIG 2. > >> >> Finally, to return to the configuration in figure 1, the capacitors >> >> are equal-valued and in series, so the value of each must be twice >> >> the value of the single cap shown in figure 2, or 534nF each. >> >> >> >> That's about half a microfarad each for a 12mA load, so if the load >> >> goes to 120mA the caps go to about 5.5�F each, and to about 55�F >> >> each for a 1200mA load. >> >> >> >> Because of that and because of the safety issues surrounding using >> >> caps for off-line voltage droppers, transformers start looking >> >> better than caps somewhere between three and ten VA, I'd guess, with >> >> anything notmuch higher than that being no contest. > >> >The C in your circuit acts like a dropper or ballast, it doesn't give full isolation. Touch the load and you can still get a shock. Cs on both L&N give a load floating at half mains V, ground the load and i doubles. > >> I disagree in that the shock can only occur if the toucher isn't >> floating, and since the capacitors' dielectric provides the >> insulation to prevent ohmic contact between the load and either side >> of the mains, the load is, by definition, isolated. > >Lets be clear here. Capacitors pass current at 110/230v ac. How much current depends on the capacitance. A cap that passed 1A to a load would also pass about 1A to a human, frying them. Its only safe when, among other things, the cap is small enough to limit current to a touch-safe value. > > >> In addition, the OP's: >> >> "Indeed, it is very much possible to provide galvanic isolation with >> capacitors for AC, and in fact, capacitive reactance may be used to >> reduce high mains side current(5A) on manageable isolated load side, >> as well." >> >> seems to indicate interest in situations where the load will be >> floating, so even a single-capacitor solution should work for him. > >Single caps work ok for the load, but leave a potential toucher touching the mains directly. > > >> >I've long thought that CR droppers would make the basis of good power supplies for sub-mA [touchable] loads, and could be allowed quite safely. > >> I'd only ever advocate the use of a reactively controlled supply if >> it was used in a double-insulated device. > >If the caps are suitably rated and sized, and you have sufficient current control for safety from either C or R in the psu, you get something needing multiple failures for any risk to occur, which is perfectly satisfactory safety-wise. At that point there is no need for any insulation from the user. > >Such supplies could run many small digital electronics, maybe some clocks, and perhaps audio devices using a piezo type speaker. > > >NT--- Since everything I wrote referred to a floating load, was geared to respond to the OP's query, and nowhere mentioned providing access to either side of the load for humans or other machines to touch, It seems you're setting up straw men in order to try to shoot down I don't know what... Do you?
Reply by ●November 30, 20142014-11-30
On Saturday, November 29, 2014 5:23:09 PM UTC-8, rickman wrote: [about ungrounded TV power connection]> Hot chassis have not be used here in over 50 years!Maybe not for modern TVs (with touchable inputs for sound, VGA video, HDMI, composite video, component video, etc.), but for simpler items (like a clock-radio) that's still a viable design strategy.
Reply by ●November 30, 20142014-11-30
On Sunday, November 30, 2014 2:26:18 AM UTC+1, Clifford Heath wrote:> On 29/11/14 08:23, Jasen Betts wrote: > > On 2014-11-28, Phil Allison <pallison49@gmail.com> wrote: > >> daku...@gmail.com wrote: > >>> Recently, > >>> we were discussing the general issue of > >>> galvanic isolation, and one of the items > >>> discussed was capacitive isolation. Indeed, > >>> it is very much possible to provide galvanic > >>> isolation with capacitors for AC, and in > >>> fact, capacitive reactance may be used > >>> to reduce high mains side current(5A) > >>> on manageable isolated load side, as well. > >>> May be this scheme could be used in some > >>> low power power supplies. Surely this would > >>> reduce the time needed to wind transformer > >>> coils. > >> > >> > >> ** You are talking complete bollocks. > >> > >> Capacitive *galvanic* isolation from the AC supply only works for signals - not power. > > > > increase the power frequency to several megahertzc and you can push > > quite a bit through capacitors > > 2nF requires 80MHz to reach 1 ohm. Are you sure you want a kilowatt of > 80MHz just to save on magnetics?If you need a low cost, low power supply, the high frequency low capacity coupling idea is good. The limiting factor is, beyond EMC, the approval agency maximum "leakage" current over the barrier (for domestic is is often 0.5mA at 230V ac, so the capacitance must be below 6nF) Cheers Klaus
Reply by ●November 30, 20142014-11-30
On 11/30/2014 4:41 PM, risskovboligrenovering@gmail.com wrote:> On Sunday, November 30, 2014 2:26:18 AM UTC+1, Clifford Heath wrote: >> On 29/11/14 08:23, Jasen Betts wrote: >>> On 2014-11-28, Phil Allison <pallison49@gmail.com> wrote: >>>> daku...@gmail.com wrote: >>>>> Recently, >>>>> we were discussing the general issue of >>>>> galvanic isolation, and one of the items >>>>> discussed was capacitive isolation. Indeed, >>>>> it is very much possible to provide galvanic >>>>> isolation with capacitors for AC, and in >>>>> fact, capacitive reactance may be used >>>>> to reduce high mains side current(5A) >>>>> on manageable isolated load side, as well. >>>>> May be this scheme could be used in some >>>>> low power power supplies. Surely this would >>>>> reduce the time needed to wind transformer >>>>> coils. >>>> >>>> >>>> ** You are talking complete bollocks. >>>> >>>> Capacitive *galvanic* isolation from the AC supply only works for signals - not power. >>> >>> increase the power frequency to several megahertzc and you can push >>> quite a bit through capacitors >> >> 2nF requires 80MHz to reach 1 ohm. Are you sure you want a kilowatt of >> 80MHz just to save on magnetics? > > If you need a low cost, low power supply, the high frequency low capacity coupling idea is good. > > The limiting factor is, beyond EMC, the approval agency maximum "leakage" current over the barrier (for domestic is is often 0.5mA at 230V ac, so the capacitance must be below 6nF) > > Cheers > > Klaus >Surely you risk RF burns doing this, besides all the cost and complexity disadvantages. You might not die from a bad RF burn the way you might from 50/60 Hz, but you might wish you had. :( Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net
Reply by ●November 30, 20142014-11-30
On Sunday, November 30, 2014 10:46:18 PM UTC+1, Phil Hobbs wrote:> On 11/30/2014 4:41 PM, risskovboligrenovering@gmail.com wrote: > > On Sunday, November 30, 2014 2:26:18 AM UTC+1, Clifford Heath wrote: > >> On 29/11/14 08:23, Jasen Betts wrote: > >>> On 2014-11-28, Phil Allison <pallison49@gmail.com> wrote: > >>>> daku...@gmail.com wrote: > >>>>> Recently, > >>>>> we were discussing the general issue of > >>>>> galvanic isolation, and one of the items > >>>>> discussed was capacitive isolation. Indeed, > >>>>> it is very much possible to provide galvanic > >>>>> isolation with capacitors for AC, and in > >>>>> fact, capacitive reactance may be used > >>>>> to reduce high mains side current(5A) > >>>>> on manageable isolated load side, as well. > >>>>> May be this scheme could be used in some > >>>>> low power power supplies. Surely this would > >>>>> reduce the time needed to wind transformer > >>>>> coils. > >>>> > >>>> > >>>> ** You are talking complete bollocks. > >>>> > >>>> Capacitive *galvanic* isolation from the AC supply only works for signals - not power. > >>> > >>> increase the power frequency to several megahertzc and you can push > >>> quite a bit through capacitors > >> > >> 2nF requires 80MHz to reach 1 ohm. Are you sure you want a kilowatt of > >> 80MHz just to save on magnetics? > > > > If you need a low cost, low power supply, the high frequency low capacity coupling idea is good. > > > > The limiting factor is, beyond EMC, the approval agency maximum "leakage" current over the barrier (for domestic is is often 0.5mA at 230V ac, so the capacitance must be below 6nF) > > > > Cheers > > > > Klaus > > > > Surely you risk RF burns doing this, besides all the cost and complexity > disadvantages. You might not die from a bad RF burn the way you might > from 50/60 Hz, but you might wish you had. :( >RF burn? Where might that come from? The HF loop is closed. Square wave generator/buffer -> Two plate capacitors -> bridge rectifier -> Load. No HF escapes the loop, only low frequency mains leakage is running across the barrier Cheers Klaus
Reply by ●November 30, 20142014-11-30
On Saturday, November 29, 2014 3:29:25 PM UTC, rickman wrote:> On 11/29/2014 10:11 AM, meow2222@care2.com wrote: > > On Saturday, November 29, 2014 2:31:07 PM UTC, rickman wrote: > >> On 11/29/2014 9:04 AM, meow2222@care2.com wrote: > >>> On Saturday, November 29, 2014 7:41:59 AM UTC, John Fields wrote: > >>>> On Fri, 28 Nov 2014 03:00:12 -0800 (PST), meow2222@care2.com wrote: > >>>>> On Friday, November 28, 2014 9:26:13 AM UTC, John Fields wrote: > >>>>>> On Thu, 27 Nov 2014 20:57:10 -0800 (PST), dakupoto@gmail.com wrote=:> >>>>>>> On Thursday, November 27, 2014 12:45:53 PM UTC-5, John Fields wro=te:> >>>>>>>> On Wed, 26 Nov 2014 21:21:58 -0800 (PST), dakupoto@gmail.com wro=te:> >>> If the caps are suitably rated and sized, and you have sufficient cur=rent control for safety from either C or R in the psu, you get something ne= eding multiple failures for any risk to occur, which is perfectly satisfact= ory safety-wise. At that point there is no need for any insulation from the= user.> >> > >> I've always wondered about the wisdom of the "multiple" failure method > >> to minimize risk. Like "double insulated" hand tools, vs. grounded > >> devices. If one layer of the insulation fails you are not exposed to =a> >> shock. But at that point the tool is only "single insulated" and the > >> low risk has just become much higher. If there is no way to determine > >> that one of the two protections has failed, there can potentially be > >> many devices running around that are just one failure away from an > >> accident. > > > > There are. Its a big improvement. >=20 > There are what? What is a big improvement?there are:> >> many devices running around that are just one failure away from an > >> accident.Its a big improvement on nearly all devices in such a condition, as used to= be the case [until the 1970s in the UK].> >> Potentially, again if there is no way to verify the proper functioning > >> of each layer of protection, such a device could have been manufacture=d> >> with one layer of protection defective. > > > > Plenty of those about.> I'm not convinced we weren't a lot better with mandatory grounds on all==20> hand held power tools.... other than the battery powered ones of course,==20> lol.I certainly prefer earthed power tools, fwiw NT
Reply by ●November 30, 20142014-11-30
On Sunday, November 30, 2014 5:25:25 PM UTC, John Fields wrote:> On Sat, 29 Nov 2014 06:04:39 -0800 (PST), meow2222@care2.com wrote: > >On Saturday, November 29, 2014 7:41:59 AM UTC, John Fields wrote: > >> On Fri, 28 Nov 2014 03:00:12 -0800 (PST), meow2222@care2.com wrote: > >> >On Friday, November 28, 2014 9:26:13 AM UTC, John Fields wrote: > >> >> On Thu, 27 Nov 2014 20:57:10 -0800 (PST), dakupoto@gmail.com wrote: > >> >> >On Thursday, November 27, 2014 12:45:53 PM UTC-5, John Fields wrot=e:> >> >> >> On Wed, 26 Nov 2014 21:21:58 -0800 (PST), dakupoto@gmail.com wro=te:> > > > > >> >> For example, consider 120 volt 60Hz mains being used to drive a > >> >> 12V/12mA load through two capacitors for "perfect" isolation from > >> >> both sides of the mains: > >> >>=20 > >> >> C1 > >> >> 120L>-----[CAP]----+ > >> >> |R1 > >> >> [1000R] > >> >> C2 | > >> >> 120N>-----[CAP]----+=20 > >> >>=20 > >> >> FIG 1. > >> >>=20 > >> >> In order to make life easier, though, we can combine C1 and C2 -for > >> >> now - and have our circuit look like this: > >> >>=20 > >> >> E1 E2 > >> >> / C1 / > >> >> 120L>-----[CAP]----+ > >> >> |R1 > >> >> [1000R] > >> >> <--I1--> | > >> >> 120N>--------------+=20 > >> >>=20 > >> >> FIG 2. > > > >> >> Finally, to return to the configuration in figure 1, the capacitors > >> >> are equal-valued and in series, so the value of each must be twice > >> >> the value of the single cap shown in figure 2, or 534nF each. > >> >>=20 > >> >> That's about half a microfarad each for a 12mA load, so if the load > >> >> goes to 120mA the caps go to about 5.5=E6=B9=A9 each, and to about =55=E6=B9=A9> >> >> each for a 1200mA load. > >> >>=20 > >> >> Because of that and because of the safety issues surrounding using > >> >> caps for off-line voltage droppers, transformers start looking > >> >> better than caps somewhere between three and ten VA, I'd guess, wit=h> >> >> anything notmuch higher than that being no contest. =20 > > > >> >The C in your circuit acts like a dropper or ballast, it doesn't give=full isolation. Touch the load and you can still get a shock. Cs on both L= &N give a load floating at half mains V, ground the load and i doubles.> > > >> I disagree in that the shock can only occur if the toucher isn't > >> floating, and since the capacitors' dielectric provides the > >> insulation to prevent ohmic contact between the load and either side > >> of the mains, the load is, by definition, isolated. > > > >Lets be clear here. Capacitors pass current at 110/230v ac. How much cur=rent depends on the capacitance. A cap that passed 1A to a load would also = pass about 1A to a human, frying them. Its only safe when, among other thin= gs, the cap is small enough to limit current to a touch-safe value.> > > > > >> In addition, the OP's: > >>=20 > >> "Indeed, it is very much possible to provide galvanic isolation with > >> capacitors for AC, and in fact, capacitive reactance may be used to > >> reduce high mains side current(5A) on manageable isolated load side, > >> as well." > >>=20 > >> seems to indicate interest in situations where the load will be > >> floating, so even a single-capacitor solution should work for him. > > > >Single caps work ok for the load, but leave a potential toucher touching=the mains directly.> > > > > >> >I've long thought that CR droppers would make the basis of good power=supplies for sub-mA [touchable] loads, and could be allowed quite safely.> > > >> I'd only ever advocate the use of a reactively controlled supply if > >> it was used in a double-insulated device. > > > >If the caps are suitably rated and sized, and you have sufficient curren=t control for safety from either C or R in the psu, you get something needi= ng multiple failures for any risk to occur, which is perfectly satisfactory= safety-wise. At that point there is no need for any insulation from the us= er.> > > >Such supplies could run many small digital electronics, maybe some clock=s, and perhaps audio devices using a piezo type speaker.> Since everything I wrote referred to a floating load, was geared to > respond to the OP's query, and nowhere mentioned providing access to > either side of the load for humans or other machines to touch, It > seems you're setting up straw men in order to try to shoot down I > don't know what... >=20 > Do you?And what I wrote was clearly about touchable psus... that's life. Not sure = where you get the straw man bit from. Yeah, the shift in the thread seems c= lear enough, a few paragraphs up. NT
Reply by ●November 30, 20142014-11-30
On Sat, 29 Nov 2014 08:13:02 -0800 (PST), Lasse Langwadt Christensen <langwadt@fonz.dk> wrote:> >> >> Potentially, again if there is no way to verify the proper =functioning>> >> of each layer of protection, such a device could have been =manufactured>> >> with one layer of protection defective. >> > >> > Plenty of those about. >>=20 >> I'm not convinced we weren't a lot better with mandatory grounds on =all=20>> hand held power tools.... other than the battery powered ones of =course,=20>> lol. >>=20 > >Around here very little is grounded, most sockets and plugs don't even =have>ground. ground fault interrupter is mandatory =20 > >The biggest problem is that it puts the chassis of most things with =switching supplies at 120V via the Y capacitors>It'll give you good jolt if you touch something grounded and a computer,==20>plenty of inputs have been killed by plugging an ungrounded computer =into a TV>grounded via the antenna cable > >-LasseIn a lot of places where the device is electric supply is from two hot wire without any neutral (including such instances here in the US) they use an X capacitor instead of a Y capacitor. ?-) =20
