Re: PC Interference from shredder Was: Kinda fun
This is why I have some sympathy for the military guys who have to decide what knowledge to classify. We're told all the horror stories about stupidly-held secrets that don't need to be secrets, and it isn’t that I don't believe them. And the boundaries of one military airfield may not be that big a deal. But sometimes really important secrets can be noodled out from seemingly innocent data, and knowing that one can't foresee all the problems must keep those guys up at night. --- Bob Bridges, robhbrid...@gmail.com, cell 336 382-7313 /* Space isn't remote at all. It's only an hour's drive away, if your car could go straight upward. -Sir Fred Hoyle */ -Original Message- From: IBM Mainframe Discussion List On Behalf Of Paul Gilmartin Sent: Sunday, November 12, 2023 08:56 A co-worker had worked for the FAA at a commercial airport near a military airfield. Military controlled its airspace; airport controlled its. He made a scatter plot of where planes vanished from civilian control, thinking it might be useful..He showed it to a military colleague who was aghast that the boundary of military control, classified, was publicly available. -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
Re: PC Interference from shredder Was: Kinda fun
When I was at Orange Coast College in the mid-70s, we had a 370-155 that had non-IBM memory. The College had a microwave link between the Costa Mesa campus and the Huntington Beach campus. The microwave link was at the campus library, and they fired it up about 9AM each week-day. The computer center was in the path between the two campuses. We would get machine checks each morning and about two minutes or so later, the system would IPL and everything would be fine until the next morning. We finally got someone to look at the problem, and if I remember correctly, the microwave dish was slightly out of alignment and once they fixed that, no more machine checks. Lloyd Sent from AT Yahoo Mail for iPad On Sunday, November 12, 2023, 8:55 AM, Paul Gilmartin <042bfe9c879d-dmarc-requ...@listserv.ua.edu> wrote: On Sun, 12 Nov 2023 10:48:19 +0100, Bernd Oppolzer wrote: > >At some point he looked out of the window and he saw the radar tower, >which is about >half a mile away and is needed for the traffic control of the airport >nearby. So he speculated > A co-worker had worked for the FAA at a commercial airport near a military airfield. Military controlled its airspace; airport controlled its. He made a scatter plot of where planes vanished from civilian control, thinking it might be useful..He showed it to a military colleague who was aghast that the boundary of military control, classified, was publicly available. I heard a story of a physics lab that tried to operate a computer room next to a spark chamber. -- gil -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
Re: PC Interference from shredder Was: Kinda fun
On Sun, 12 Nov 2023 10:48:19 +0100, Bernd Oppolzer wrote: > >At some point he looked out of the window and he saw the radar tower, >which is about >half a mile away and is needed for the traffic control of the airport >nearby. So he speculated > A co-worker had worked for the FAA at a commercial airport near a military airfield. Military controlled its airspace; airport controlled its. He made a scatter plot of where planes vanished from civilian control, thinking it might be useful..He showed it to a military colleague who was aghast that the boundary of military control, classified, was publicly available. I heard a story of a physics lab that tried to operate a computer room next to a spark chamber. -- gil -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
Re: PC Interference from shredder Was: Kinda fun
I like these stories. in the nineties I had similar problems with my new computer, which had external SCSI drives in a separate box, and a 1,5 meter SCSI cable between this box and the PC tower. A friend of mine who knows more about electrical engineering than I do came along to look for the problem. At some point he looked out of the window and he saw the radar tower, which is about half a mile away and is needed for the traffic control of the airport nearby. So he speculated about the problems coming from the radar pulses ... in fact, my office at that time was in the 3rd floor of the house, and we're just in between the tower and the main entry path of the airplanes. I don't recall exactly how we fixed the problem ... today, the computer is still in use, but now it is in the 2nd floor :-) in my private computer museum (OS/2 box, still running). Kind regards Bernd Am 12.11.2023 um 02:50 schrieb Steve Thompson: Many years ago at Hagerstown MD, they had a computer (I think it was an NCR3 or 3000, it's just been too long ago) that at odd points would just fail. My father was an RF tech working on radios, and had a contract for the Police Department... so I will make this short. It turns out that a few stories below this computer room was the door out of the garage where the police cars were parked. And so upon exiting the parking garage and entering the alley to the street, officers would key their mics to verify their radio was working and that would cause the computer system to lock up (machine check?). This was discovered by an NCR CE that had an Oscilloscope doing tracing trying to find what was causing this problem and just happened to be standing at the window looking down when a police car came out and the machine froze. the police mobile radios were a harmonic of the system clock!! And were 100 Watts IRC. A sign was put at the exit of the garage informing anyone who keyed their mic for their radio before getting out of the alley, upon being discovered who they were, their pay check would be the last one to be passed out at the end of the month. This problem had been invariably happening during payroll runs and they had to be restarted from the beginning. Problem stopped. Steve Thompson Oh, and the windows did have a metal grid over them in an attempt to prevent things like this. On 11/11/2023 5:07 PM, Tom Brennan wrote: Just before I worked with mainframes I drew maps on a computer that had a big display, a small drawing pad and pen, and a large light table with a "puck" for tracing existing maps into the computer. Both the puck and pen worked by receiving a magnetic signal from the pad or table in order to determine its location. About once a week someone would complain that their pen was throwing the cursor all over the screen, so a new pen was ordered at maybe $500. The light table had bunch of fluorescent bulbs inside, and you could dim them with a knob if needed. One day I noticed that when the light was either full on or full off, there was no problem with my pen. But if the dimmer was in the middle, the pen had issues. Those dimmers used triacs which work by holding back each AC wave a bit and then sharply rising. The sharp rise generates all sorts of EMF and that's what was messing with the coil in the pen. On 11/11/2023 12:55 PM, Wayne Bickerdike wrote: On the subject of RF interference. Years ago we came back from living in California to Australia. We had a 110V coffee espresso machine. It worked well and we ran it from a voltage changer plugged into the socket. Early rise time, my wife would go into the kitchen and make a coffee. I'm in the habit of reading my email and surfing at that time (like now in Australia). For weeks and months my internet would go off and come back a few minutes later. I eventually tied it back to the coffee machine/voltage reducer. We stopped using it and all good. The wireless router runs on 2.4Ghz and is located in my study, maybe 30 feet from the kitchen and there is a double brick wall in the way. As an adjunct to this. I switch off my router at midnight and I get much better sleep. On Sun, Nov 12, 2023 at 6:11 AM Joel C. Ewing wrote: I think shielding of the PC itself is unlikely the problem, unless the case is not properly closed. All PCs I have ever seen have metal cases, which if properly seated and grounded act as a RF shield, inbound and outbound. Any electric motor could be producing power transients at power on/off and possible RF interference from contact arcing (which can increase with motor age), which might travel over the house wiring, or via air and get picked up by other cables in the room which are connected to the PC. Any magnetic effects of a motor should be minor by comparison. If it's a large enough motor, start up may produce a temporary dip in voltage big enough to be a problem for a computer that is not powered through an
Re: PC Interference from shredder Was: Kinda fun
Maybe if they covered the walls too? https://www.amazon.com/Reducing-Wallpaper-Faraday-Copper-Radiation-Shielding/dp/B09BW3CYQB On Sat, Nov 11, 2023 at 7:51 PM Steve Thompson wrote: > Many years ago at Hagerstown MD, they had a computer (I think it > was an NCR3 or 3000, it's just been too long ago) that at odd > points would just fail. My father was an RF tech working on > radios, and had a contract for the Police Department... so I will > make this short. It turns out that a few stories below this > computer room was the door out of the garage where the police > cars were parked. And so upon exiting the parking garage and > entering the alley to the street, officers would key their mics > to verify their radio was working and that would cause the > computer system to lock up (machine check?). > > This was discovered by an NCR CE that had an Oscilloscope doing > tracing trying to find what was causing this problem and just > happened to be standing at the window looking down when a police > car came out and the machine froze. the police mobile radios > were a harmonic of the system clock!! And were 100 Watts IRC. > > A sign was put at the exit of the garage informing anyone who > keyed their mic for their radio before getting out of the alley, > upon being discovered who they were, their pay check would be the > last one to be passed out at the end of the month. This problem > had been invariably happening during payroll runs and they had to > be restarted from the beginning. > > Problem stopped. > > Steve Thompson > > Oh, and the windows did have a metal grid over them in an attempt > to prevent things like this. > > On 11/11/2023 5:07 PM, Tom Brennan wrote: > > Just before I worked with mainframes I drew maps on a computer > > that had a big display, a small drawing pad and pen, and a > > large light table with a "puck" for tracing existing maps into > > the computer. Both the puck and pen worked by receiving a > > magnetic signal from the pad or table in order to determine its > > location. About once a week someone would complain that their > > pen was throwing the cursor all over the screen, so a new pen > > was ordered at maybe $500. > > > > The light table had bunch of fluorescent bulbs inside, and you > > could dim them with a knob if needed. One day I noticed that > > when the light was either full on or full off, there was no > > problem with my pen. But if the dimmer was in the middle, the > > pen had issues. Those dimmers used triacs which work by > > holding back each AC wave a bit and then sharply rising. The > > sharp rise generates all sorts of EMF and that's what was > > messing with the coil in the pen. > > > > On 11/11/2023 12:55 PM, Wayne Bickerdike wrote: > >> On the subject of RF interference. Years ago we came back from > >> living in > >> California to Australia. We had a 110V coffee espresso > >> machine. It worked > >> well and we ran it from a voltage changer plugged into the > >> socket. Early > >> rise time, my wife would go into the kitchen and make a coffee. > >> > >> I'm in the habit of reading my email and surfing at that time > >> (like now in > >> Australia). > >> > >> For weeks and months my internet would go off and come back a few > >> minutes later. I eventually tied it back to the coffee > >> machine/voltage > >> reducer. We stopped using it and all good. The wireless router > >> runs on > >> 2.4Ghz and is located in my study, maybe 30 feet from the > >> kitchen and there > >> is a double brick wall in the way. > >> > >> As an adjunct to this. I switch off my router at midnight and > >> I get much > >> better sleep. > >> > >> On Sun, Nov 12, 2023 at 6:11 AM Joel C. Ewing > >> wrote: > >> > >>> I think shielding of the PC itself is unlikely the problem, > >>> unless the > >>> case is not properly closed. All PCs I have ever seen have > >>> metal cases, > >>> which if properly seated and grounded act as a RF shield, > >>> inbound and > >>> outbound. > >>> > >>> Any electric motor could be producing power transients at > >>> power on/off > >>> and possible RF interference from contact arcing (which can > >>> increase > >>> with motor age), which might travel over the house wiring, or > >>> via air > >>> and get picked up by other cables in the room which are > >>> connected to the > >>> PC. Any magnetic effects of a motor should be minor by > >>> comparison. > >>> > >>> If it's a large enough motor, start up may produce a > >>> temporary dip in > >>> voltage big enough to be a problem for a computer that is not > >>> powered > >>> through an Uninterruptible Power Supply (UPS). If you notice > >>> any lights > >>> flicker when the shredder powers up, that definitely could be > >>> an issue. > >>> If you are not already using a UPS for your PC, you probably > >>> should be, > >>> for other reasons as well. The shredder definitely should not > >>> be plugged > >>> into the same outlet as your computer, and it would be best > >>> if it were > >>> on a
Re: PC Interference from shredder Was: Kinda fun
Many years ago at Hagerstown MD, they had a computer (I think it was an NCR3 or 3000, it's just been too long ago) that at odd points would just fail. My father was an RF tech working on radios, and had a contract for the Police Department... so I will make this short. It turns out that a few stories below this computer room was the door out of the garage where the police cars were parked. And so upon exiting the parking garage and entering the alley to the street, officers would key their mics to verify their radio was working and that would cause the computer system to lock up (machine check?). This was discovered by an NCR CE that had an Oscilloscope doing tracing trying to find what was causing this problem and just happened to be standing at the window looking down when a police car came out and the machine froze. the police mobile radios were a harmonic of the system clock!! And were 100 Watts IRC. A sign was put at the exit of the garage informing anyone who keyed their mic for their radio before getting out of the alley, upon being discovered who they were, their pay check would be the last one to be passed out at the end of the month. This problem had been invariably happening during payroll runs and they had to be restarted from the beginning. Problem stopped. Steve Thompson Oh, and the windows did have a metal grid over them in an attempt to prevent things like this. On 11/11/2023 5:07 PM, Tom Brennan wrote: Just before I worked with mainframes I drew maps on a computer that had a big display, a small drawing pad and pen, and a large light table with a "puck" for tracing existing maps into the computer. Both the puck and pen worked by receiving a magnetic signal from the pad or table in order to determine its location. About once a week someone would complain that their pen was throwing the cursor all over the screen, so a new pen was ordered at maybe $500. The light table had bunch of fluorescent bulbs inside, and you could dim them with a knob if needed. One day I noticed that when the light was either full on or full off, there was no problem with my pen. But if the dimmer was in the middle, the pen had issues. Those dimmers used triacs which work by holding back each AC wave a bit and then sharply rising. The sharp rise generates all sorts of EMF and that's what was messing with the coil in the pen. On 11/11/2023 12:55 PM, Wayne Bickerdike wrote: On the subject of RF interference. Years ago we came back from living in California to Australia. We had a 110V coffee espresso machine. It worked well and we ran it from a voltage changer plugged into the socket. Early rise time, my wife would go into the kitchen and make a coffee. I'm in the habit of reading my email and surfing at that time (like now in Australia). For weeks and months my internet would go off and come back a few minutes later. I eventually tied it back to the coffee machine/voltage reducer. We stopped using it and all good. The wireless router runs on 2.4Ghz and is located in my study, maybe 30 feet from the kitchen and there is a double brick wall in the way. As an adjunct to this. I switch off my router at midnight and I get much better sleep. On Sun, Nov 12, 2023 at 6:11 AM Joel C. Ewing wrote: I think shielding of the PC itself is unlikely the problem, unless the case is not properly closed. All PCs I have ever seen have metal cases, which if properly seated and grounded act as a RF shield, inbound and outbound. Any electric motor could be producing power transients at power on/off and possible RF interference from contact arcing (which can increase with motor age), which might travel over the house wiring, or via air and get picked up by other cables in the room which are connected to the PC. Any magnetic effects of a motor should be minor by comparison. If it's a large enough motor, start up may produce a temporary dip in voltage big enough to be a problem for a computer that is not powered through an Uninterruptible Power Supply (UPS). If you notice any lights flicker when the shredder powers up, that definitely could be an issue. If you are not already using a UPS for your PC, you probably should be, for other reasons as well. The shredder definitely should not be plugged into the same outlet as your computer, and it would be best if it were on a different house circuit as well. If the problem only started occurring after adding RAM, maybe the PC power supply is now working harder making it more sensitive to power dips than before. It's also possible the computer may be getting old enough that the power supply is getting less effective at filtering out RF. If for some reason the shredder motor is broadcasting more RF interference than in the past, keeping it further away from any cables connecting devices to the PC may help. There are also some relatively inexpensive ferrite beads that can be clipped onto
Re: PC Interference from shredder Was: Kinda fun
Just before I worked with mainframes I drew maps on a computer that had a big display, a small drawing pad and pen, and a large light table with a "puck" for tracing existing maps into the computer. Both the puck and pen worked by receiving a magnetic signal from the pad or table in order to determine its location. About once a week someone would complain that their pen was throwing the cursor all over the screen, so a new pen was ordered at maybe $500. The light table had bunch of fluorescent bulbs inside, and you could dim them with a knob if needed. One day I noticed that when the light was either full on or full off, there was no problem with my pen. But if the dimmer was in the middle, the pen had issues. Those dimmers used triacs which work by holding back each AC wave a bit and then sharply rising. The sharp rise generates all sorts of EMF and that's what was messing with the coil in the pen. On 11/11/2023 12:55 PM, Wayne Bickerdike wrote: On the subject of RF interference. Years ago we came back from living in California to Australia. We had a 110V coffee espresso machine. It worked well and we ran it from a voltage changer plugged into the socket. Early rise time, my wife would go into the kitchen and make a coffee. I'm in the habit of reading my email and surfing at that time (like now in Australia). For weeks and months my internet would go off and come back a few minutes later. I eventually tied it back to the coffee machine/voltage reducer. We stopped using it and all good. The wireless router runs on 2.4Ghz and is located in my study, maybe 30 feet from the kitchen and there is a double brick wall in the way. As an adjunct to this. I switch off my router at midnight and I get much better sleep. On Sun, Nov 12, 2023 at 6:11 AM Joel C. Ewing wrote: I think shielding of the PC itself is unlikely the problem, unless the case is not properly closed. All PCs I have ever seen have metal cases, which if properly seated and grounded act as a RF shield, inbound and outbound. Any electric motor could be producing power transients at power on/off and possible RF interference from contact arcing (which can increase with motor age), which might travel over the house wiring, or via air and get picked up by other cables in the room which are connected to the PC. Any magnetic effects of a motor should be minor by comparison. If it's a large enough motor, start up may produce a temporary dip in voltage big enough to be a problem for a computer that is not powered through an Uninterruptible Power Supply (UPS). If you notice any lights flicker when the shredder powers up, that definitely could be an issue. If you are not already using a UPS for your PC, you probably should be, for other reasons as well. The shredder definitely should not be plugged into the same outlet as your computer, and it would be best if it were on a different house circuit as well. If the problem only started occurring after adding RAM, maybe the PC power supply is now working harder making it more sensitive to power dips than before. It's also possible the computer may be getting old enough that the power supply is getting less effective at filtering out RF. If for some reason the shredder motor is broadcasting more RF interference than in the past, keeping it further away from any cables connecting devices to the PC may help. There are also some relatively inexpensive ferrite beads that can be clipped onto cables near the computer to block RFI from entering via that route. Assuming you are in a house, the simplest experiment is to try moving the shredder to another room far away from the PC where it can be powered from a different house circuit. If that eliminates the problem and having the shredder in a different room is acceptable, moving the shredder away from the PC may be the simplest short-term solution. Otherwise you can either try using a UPS for the PC and/or adding ferrite RF filters on PC device cables that don't already include a filter, especially if there are any cables that are routed close to the shredder. JC Ewing On 11/11/23 06:34, Bob Bridges wrote: Hah! A few years ago I had my hardware-geek son build my latest tower PC. It's pretty good - not water-cooled like the one he made for himself, but a nice big monitor and I finally gave him permission to load me up on RAM. But ... Do normal commercial PCs have Faraday cage around them, or something? I can't use my old paper shredder any more, because when it fires up within the same room, the PC suddenly dies and has to be rebooted. A minor EMP, I take it. --- Bob Bridges, robhbrid...@gmail.com, cell 336 382-7313 /* The will to win is not nearly as important as the will to prepare to win. -R.M. Knight */ -Original Message- From: IBM Mainframe Discussion List On Behalf Of Leonard D Woren Sent: Saturday, November 11, 2023 02:12 Long ago I was told why my shop didn't carpet the tape storage area.
Re: PC Interference from shredder Was: Kinda fun
Microwaves can do that https://www.theguardian.com/science/2015/may/05/microwave-oven-caused-mystery-signal-plaguing-radio-telescope-for-17-years On Sat, Nov 11, 2023 at 2:55 PM Wayne Bickerdike wrote: > On the subject of RF interference. Years ago we came back from living in > California to Australia. We had a 110V coffee espresso machine. It worked > well and we ran it from a voltage changer plugged into the socket. Early > rise time, my wife would go into the kitchen and make a coffee. > > I'm in the habit of reading my email and surfing at that time (like now in > Australia). > > For weeks and months my internet would go off and come back a few > minutes later. I eventually tied it back to the coffee machine/voltage > reducer. We stopped using it and all good. The wireless router runs on > 2.4Ghz and is located in my study, maybe 30 feet from the kitchen and there > is a double brick wall in the way. > > As an adjunct to this. I switch off my router at midnight and I get much > better sleep. > > On Sun, Nov 12, 2023 at 6:11 AM Joel C. Ewing wrote: > > > I think shielding of the PC itself is unlikely the problem, unless the > > case is not properly closed. All PCs I have ever seen have metal cases, > > which if properly seated and grounded act as a RF shield, inbound and > > outbound. > > > > Any electric motor could be producing power transients at power on/off > > and possible RF interference from contact arcing (which can increase > > with motor age), which might travel over the house wiring, or via air > > and get picked up by other cables in the room which are connected to the > > PC. Any magnetic effects of a motor should be minor by comparison. > > > > If it's a large enough motor, start up may produce a temporary dip in > > voltage big enough to be a problem for a computer that is not powered > > through an Uninterruptible Power Supply (UPS). If you notice any lights > > flicker when the shredder powers up, that definitely could be an issue. > > If you are not already using a UPS for your PC, you probably should be, > > for other reasons as well. The shredder definitely should not be plugged > > into the same outlet as your computer, and it would be best if it were > > on a different house circuit as well. > > > > If the problem only started occurring after adding RAM, maybe the PC > > power supply is now working harder making it more sensitive to power > > dips than before. It's also possible the computer may be getting old > > enough that the power supply is getting less effective at filtering out > RF. > > > > If for some reason the shredder motor is broadcasting more RF > > interference than in the past, keeping it further away from any cables > > connecting devices to the PC may help. There are also some relatively > > inexpensive ferrite beads that can be clipped onto cables near the > > computer to block RFI from entering via that route. > > > > Assuming you are in a house, the simplest experiment is to try moving > > the shredder to another room far away from the PC where it can be > > powered from a different house circuit. If that eliminates the problem > > and having the shredder in a different room is acceptable, moving the > > shredder away from the PC may be the simplest short-term solution. > > Otherwise you can either try using a UPS for the PC and/or adding > > ferrite RF filters on PC device cables that don't already include a > > filter, especially if there are any cables that are routed close to the > > shredder. > > > > JC Ewing > > > > > > On 11/11/23 06:34, Bob Bridges wrote: > > > Hah! A few years ago I had my hardware-geek son build my latest tower > > PC. It's pretty good - not water-cooled like the one he made for > himself, > > but a nice big monitor and I finally gave him permission to load me up on > > RAM. But ... > > > > > > Do normal commercial PCs have Faraday cage around them, or something? > I > > can't use my old paper shredder any more, because when it fires up within > > the same room, the PC suddenly dies and has to be rebooted. A minor > EMP, I > > take it. > > > > > > --- > > > Bob Bridges, robhbrid...@gmail.com, cell 336 382-7313 > > > > > > /* The will to win is not nearly as important as the will to prepare to > > win. -R.M. Knight */ > > > > > > -Original Message- > > > From: IBM Mainframe Discussion List On > > Behalf Of Leonard D Woren > > > Sent: Saturday, November 11, 2023 02:12 > > > > > > Long ago I was told why my shop didn't carpet the tape storage area. > > Apparently some shop that did had a problem with unreadable tapes. > > Eventually they figured out that all the unreadable tapes were on the > > bottom row of the tape storage. And the outside cleaning people used a > > vacuum cleaner... > > > > > > --- Bob Bridges wrote on 11/8/2023 6:56 AM: > > >> /* The more sophisticated the technology, the more vulnerable it is to > > >> primitive attack. People often overlook the obvious. -Dr Who, 1978 */ > > > > >
Re: PC Interference from shredder Was: Kinda fun
On the subject of RF interference. Years ago we came back from living in California to Australia. We had a 110V coffee espresso machine. It worked well and we ran it from a voltage changer plugged into the socket. Early rise time, my wife would go into the kitchen and make a coffee. I'm in the habit of reading my email and surfing at that time (like now in Australia). For weeks and months my internet would go off and come back a few minutes later. I eventually tied it back to the coffee machine/voltage reducer. We stopped using it and all good. The wireless router runs on 2.4Ghz and is located in my study, maybe 30 feet from the kitchen and there is a double brick wall in the way. As an adjunct to this. I switch off my router at midnight and I get much better sleep. On Sun, Nov 12, 2023 at 6:11 AM Joel C. Ewing wrote: > I think shielding of the PC itself is unlikely the problem, unless the > case is not properly closed. All PCs I have ever seen have metal cases, > which if properly seated and grounded act as a RF shield, inbound and > outbound. > > Any electric motor could be producing power transients at power on/off > and possible RF interference from contact arcing (which can increase > with motor age), which might travel over the house wiring, or via air > and get picked up by other cables in the room which are connected to the > PC. Any magnetic effects of a motor should be minor by comparison. > > If it's a large enough motor, start up may produce a temporary dip in > voltage big enough to be a problem for a computer that is not powered > through an Uninterruptible Power Supply (UPS). If you notice any lights > flicker when the shredder powers up, that definitely could be an issue. > If you are not already using a UPS for your PC, you probably should be, > for other reasons as well. The shredder definitely should not be plugged > into the same outlet as your computer, and it would be best if it were > on a different house circuit as well. > > If the problem only started occurring after adding RAM, maybe the PC > power supply is now working harder making it more sensitive to power > dips than before. It's also possible the computer may be getting old > enough that the power supply is getting less effective at filtering out RF. > > If for some reason the shredder motor is broadcasting more RF > interference than in the past, keeping it further away from any cables > connecting devices to the PC may help. There are also some relatively > inexpensive ferrite beads that can be clipped onto cables near the > computer to block RFI from entering via that route. > > Assuming you are in a house, the simplest experiment is to try moving > the shredder to another room far away from the PC where it can be > powered from a different house circuit. If that eliminates the problem > and having the shredder in a different room is acceptable, moving the > shredder away from the PC may be the simplest short-term solution. > Otherwise you can either try using a UPS for the PC and/or adding > ferrite RF filters on PC device cables that don't already include a > filter, especially if there are any cables that are routed close to the > shredder. > > JC Ewing > > > On 11/11/23 06:34, Bob Bridges wrote: > > Hah! A few years ago I had my hardware-geek son build my latest tower > PC. It's pretty good - not water-cooled like the one he made for himself, > but a nice big monitor and I finally gave him permission to load me up on > RAM. But ... > > > > Do normal commercial PCs have Faraday cage around them, or something? I > can't use my old paper shredder any more, because when it fires up within > the same room, the PC suddenly dies and has to be rebooted. A minor EMP, I > take it. > > > > --- > > Bob Bridges, robhbrid...@gmail.com, cell 336 382-7313 > > > > /* The will to win is not nearly as important as the will to prepare to > win. -R.M. Knight */ > > > > -Original Message- > > From: IBM Mainframe Discussion List On > Behalf Of Leonard D Woren > > Sent: Saturday, November 11, 2023 02:12 > > > > Long ago I was told why my shop didn't carpet the tape storage area. > Apparently some shop that did had a problem with unreadable tapes. > Eventually they figured out that all the unreadable tapes were on the > bottom row of the tape storage. And the outside cleaning people used a > vacuum cleaner... > > > > --- Bob Bridges wrote on 11/8/2023 6:56 AM: > >> /* The more sophisticated the technology, the more vulnerable it is to > >> primitive attack. People often overlook the obvious. -Dr Who, 1978 */ > > > -- > Joel C. Ewing > > -- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN > -- Wayne V. Bickerdike -- For IBM-MAIN subscribe / signoff / archive access instructions, send
Re: PC Interference from shredder Was: Kinda fun
I think shielding of the PC itself is unlikely the problem, unless the case is not properly closed. All PCs I have ever seen have metal cases, which if properly seated and grounded act as a RF shield, inbound and outbound. Any electric motor could be producing power transients at power on/off and possible RF interference from contact arcing (which can increase with motor age), which might travel over the house wiring, or via air and get picked up by other cables in the room which are connected to the PC. Any magnetic effects of a motor should be minor by comparison. If it's a large enough motor, start up may produce a temporary dip in voltage big enough to be a problem for a computer that is not powered through an Uninterruptible Power Supply (UPS). If you notice any lights flicker when the shredder powers up, that definitely could be an issue. If you are not already using a UPS for your PC, you probably should be, for other reasons as well. The shredder definitely should not be plugged into the same outlet as your computer, and it would be best if it were on a different house circuit as well. If the problem only started occurring after adding RAM, maybe the PC power supply is now working harder making it more sensitive to power dips than before. It's also possible the computer may be getting old enough that the power supply is getting less effective at filtering out RF. If for some reason the shredder motor is broadcasting more RF interference than in the past, keeping it further away from any cables connecting devices to the PC may help. There are also some relatively inexpensive ferrite beads that can be clipped onto cables near the computer to block RFI from entering via that route. Assuming you are in a house, the simplest experiment is to try moving the shredder to another room far away from the PC where it can be powered from a different house circuit. If that eliminates the problem and having the shredder in a different room is acceptable, moving the shredder away from the PC may be the simplest short-term solution. Otherwise you can either try using a UPS for the PC and/or adding ferrite RF filters on PC device cables that don't already include a filter, especially if there are any cables that are routed close to the shredder. JC Ewing On 11/11/23 06:34, Bob Bridges wrote: Hah! A few years ago I had my hardware-geek son build my latest tower PC. It's pretty good - not water-cooled like the one he made for himself, but a nice big monitor and I finally gave him permission to load me up on RAM. But ... Do normal commercial PCs have Faraday cage around them, or something? I can't use my old paper shredder any more, because when it fires up within the same room, the PC suddenly dies and has to be rebooted. A minor EMP, I take it. --- Bob Bridges, robhbrid...@gmail.com, cell 336 382-7313 /* The will to win is not nearly as important as the will to prepare to win. -R.M. Knight */ -Original Message- From: IBM Mainframe Discussion List On Behalf Of Leonard D Woren Sent: Saturday, November 11, 2023 02:12 Long ago I was told why my shop didn't carpet the tape storage area. Apparently some shop that did had a problem with unreadable tapes. Eventually they figured out that all the unreadable tapes were on the bottom row of the tape storage. And the outside cleaning people used a vacuum cleaner... --- Bob Bridges wrote on 11/8/2023 6:56 AM: /* The more sophisticated the technology, the more vulnerable it is to primitive attack. People often overlook the obvious. -Dr Who, 1978 */ -- Joel C. Ewing -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
