Hi, On 31/01/2011, Brian Lanning <brianlanning at gmail.com> wrote: This doesn't look quite right to me, but it is probably close enough for most applications. In Europe, a typical property is supplied with a single 230V RMS AC single phase and neutral supply. If you pay enough money and/or are small industrial etc, you can get a three phase and neutral supply. Each phase is 230V RMS AC phase to neutral, 400V RMS AC phase to phase. The only way to get 110V RMS AC is through a stepdown transformer. I don't know enough about american 220V applicances. Many switch mode power supplies will work happliy with both 230V and 110V. The 110/230 switch only ever seemed to switch in a secondary capacitor after the bridge rectifier for the HV DC supply to the switching circuitry. I guess it was difficult to get 300VDC+ capacitors for a while. Adding a second capacitor (in series) meant that each capacitor only ever saw about 1/2 the DC voltage, and hence kept the smoke in. Simon -- ------------------------------------------------------------------------ "Well, an engineer is not concerned with the truth; that is left to philosophers and theologians: the prime concern of an engineer is the utility of the final product." Lectures on the Electrical Properties of Materials, L.Solymar, D.Walsh

-----Oorspronkelijk bericht----- Van: cctalk-bounces at classiccmp.org [mailto:cctalk-bounces at classiccmp.org] Namens E. Groenenberg Verzonden: maandag 31 januari 2011 8:50 Aan: General Discussion: On-Topic and Off-Topic Posts Onderwerp: Re: OT: american vs european 220 H, Here in the Netherlands, most domestic houses do have a single leg 240V power. For an additional 'connection fee' you can get 3 phase power delivered. I have 3 phase power at home, guess why.... Ed In most western Europe countries the power systems are 3-fase 230V with a 180 degrees phase-shift. Neutral is earthed at the distribution (10kV ->230V) transformer . So only the phase(brown) wire has a voltage potential to earth. The voltage between earth, neutral and the other legs is always 230V AC and between the 3 phase legs 400V AC. Most new houses in NL are wired for a 3 phase-system but at the power inlet just one leg is fused so the owner sees a 1 phase-system, but it easy (for the power company) to upgrade to a 3 phase-system ( 2 fuses and a new powermeter). And yes I do have a 3-phase system with also a separate earth system for measurement systems. -Rik -- Dit is een HTML vrije email / This is an HTML free email.

Brian Lanning wrote: Our clothes dryer runs the drum motor from one leg and the heaters / timer switch/cam thing driven by a small motor) but it seems sensible that other high-draw appliances might run different parts via different 110V legs, too. In the UK it was typically three 220V [1] phases to the street, I believe - but only one of those would then make it as far as the house (resulting in certain faults causing just part of the street to go dead as a phase was lost :-) [1] or 230V, or 240V... I can never remember exactly. Historically the UK was on 240V, but they harmonised with the rest of Europe which, IIRC, is 230V. As others said, a step-down would work - but the number of 220V US appliances are relatively few IME, and those that are may not require the split-power arrangement to function. One gotcha is that US power is 60Hz and Europe 50Hz, which might have an effect on anything that relies on line frequency for timing. cheers Jules

On 1/31/2011 12:50 AM, E. Groenenberg wrote: Tube audio power supply ... :)

On 31/01/2011 17:59, Alexander Schreiber wrote: Correct, in the UK it's officially 230V +10%/-6% instead of 240V +/-6%, but in practice it's generally close to 240V. At least it is for the "average" consumer; someone close to the supply transformer might actually get up to 253V and someone further down the line where the voltage has dropped might only get 216V, and still both would be within the limits. Something similar is true in other parts of Europe, of course. It makes calculations and specifications of power in water heaters and the like rather interesting: P=V^2/R so for a resistive heater the difference can be quite large. Likewise, people here often refer to 3-phase as 415V, but the standard says 400V plus/minus something. -- Pete Peter Turnbull Network Manager University of York

I was under the impression that the US mains was in fact 220V (or 230V, 234V, depending on which reference you believe), centre-tapped. The centre-tap is the 'neutral' wire and is connected to earth ground at one point. The outside 2 ieres are this 110V with respect to neutral, but as they're in antipahse there's 220V between them. Most devices are 110V and run between one live/phase wire and neutral, high-power stuff (cooking ovens, tumble driers, etc) run their heating elements between the 2 outside wires so as to reduce the current they draw. I beleive you are corrrect. IIRC the timer of a cooker or tumble drier, possibly the motor of the latter is run from 110V -- between one phase wire and neutral. Yes, exactly. The domestic mains is nomianlly 230V now. We get a single phase wire and a neurtal, the latter being close to ground. Everything is designed to run off that 230V supply. There is no 'centre tap'. So our cookers, say, have 230V elements and a timer that runs off 230V mains. Actually, the European mains is 3 phase. The final transformer secondary is start (wye?) connected with the star point being th eneautral. Houses get a single phase supply consisting of that neurral wire and one of the phase wires -- to balance the load, neighbouring hosues in a road get different phases [1]. Of coruse industral places get the full 2 phase mains to run larger motors, etc. It's very difficult to convince the electricity companies to run 3 phase mains into a normal house, though, which is a problem for people who ant to run large disk drives ;-) [1] In the cases of blocks of flats, student halls of residence, etc, it's not unheard-of for each floor to be wired to wired to a different phase. This has led to studend running extension leads to the rooms above and below theres so as to get a 3 phase supply... No, if we ant 110V, we have to provide our own step-down transfoemr It depends on what yuou are trying to do. Certainly a US appliance that needs 110V for any function is not going to work on European mains without modifications. That may be as simple as providing a small step-down transofrmer for the control unit supply. Waht are you trying to do? -tony

Not at all!. The adjustable SMPUS are designed so that the chopper cirucit works correctly with a DC inpout of around 350V. This can be obtained in 2 ways : a) By full0-wave rectifiying a 230V mains supply b) By voltage-doubling a 115V mains supply The first uses a bridge rectifier (normally) and a smoothing capacitor. The second uses a pair of diodes and a pair of capacitors. It turns out you can use 4 diodes (in a normal bridge configuration) and 2 capacitors, along with a couple of resistors to get the 2 capacitors to charge to approximatle the same voltage if you want to use the series combination as a single cacpaitror) to make a cirucit that can aci as either of those simply by adding a link for (b). That;s what happens in every dual-voltage SMPUS I've worked on. -tony

IIRC, the oigianl spec was that mainland Euriope was 220V +/- something-or-orhter, and the UK was 240V +/-somethingelse. The 'harmonisation; was to call mainland Europena mans '230V +alitle/-alot' and UK mains '230V+alt/-alittle'. In other words they fiddled with the tolerances and didn't actually change the voltages :-).. -tony

On Monday 31 January 2011, Tony Duell wrote: Sort of. Technically, there was no "ground" wire, and the appliance chassis (if connected) was connected to the neutral line. This is no longer allowed. As long as there's no electrical faults, neutral and ground should be at the same potential (but obviously for safety reasons, one shouldn't assume this). They're usually bonded together at the service entrance - wherever the main circuit breaker (which may actually be up to 6 breakers for separate loads) is. In any case, that's not allowed in new construction or appliances anymore, only grandfathered in, in existing situations. Right. Like I said, the chassis was bonded to neutral, not neutral bonded to ground. I guess it's the same situation as an 120V appliance whose chassis is bonded to the neutral line in a 2-wire, non-grounded plug. Though, ground carrying some current isn't all that uncommon. There are plenty of things that have a non-trivial leakage current (eg, MOV or other surge protector devices). I've seen some computer equipment with warnings about having a "high leakage current". -- Purdue University Research Computing --- http://www.rcac.purdue.edu/ The Computer Refuge --- http://computer-refuge.org

Obviously, european penises are 220cm long and american penises are 220in long, clearly making us superior. America loves to do things big. -- "The Direct3D Graphics Pipeline" -- DirectX 9 draft available for download <http://legalizeadulthood.wordpress.com/the-direct3d-graphics-pipeline/> Legalize Adulthood! <http://legalizeadulthood.wordpress.com>

All, On 01/02/2011, Chuck Guzis <cclist at sydex.com> wrote: I was assuming you were getting two phases from a three phase system. Tony seems to indicate that the two legs in the US are from a centre tapped transformer, so you would be getting 220/240V. [more scary US distribution wiring] Simon -- ------------------------------------------------------------------------ "Well, an engineer is not concerned with the truth; that is left to philosophers and theologians: the prime concern of an engineer is the utility of the final product." Lectures on the Electrical Properties of Materials, L.Solymar, D.Walsh

Simon Fryer wrote: There's some reasonable text about various AC systems at: http://en.wikipedia.org/wiki/Split-phase_electric_power cheers Jules

On Mon, 31 Jan 2011, Tony Duell wrote: Maybe in the UK, but in Germany it's very usual to have three phases. For example, our house gets three phases (fused at 63A each) which are then distributed to the individual rooms (one phase here, another phase there, and so on). The kitchen for example has in addition to the single phase for the light and outlets a three-phase line for the stove. And it's not unusual to have a red CEE outlet in some cases (we had one in the cellar until we needed this additional three-phase line for the separate oven). In France you can get three phases to your house (three-wire cable coming into the house), it depends on your choice whether you actually have three or only one phase available, e.g. you can have 1x60A (called "monophas?") or 3x20A ("triphas?"), the price is the same. Christian

Well, 'live chassis' ('hot chassis', whatever) radios and TVs were common over here too, but it had to be impossoible to touch the chassis or anyhting electrically connected to it (e.g. fixing screws). This is reather differnet from having the metalwork of a cooker or simuilar connected to the neuatral wire, that is most definitely touchable. Yes, you're right. I am sure there;s a limit to the mazximum permitted leackage current. It's not zero, but ti's probably not that high either. Mins filters often have cpaciaotrs from the power-carrying wires to ground, and they will pass some AC current. -tony

On 1 Feb 2011 at 19:03, Tony Duell wrote: It's been variously quoted as 110/220, 115/230, 117/234 and today, 120/240. The "standard" has crept up over the years. Japan, I believe, is still 100V, although it can be either 50 or 60 Hz. 117L7/M7GT if memory serves. Another combination was a 70L7 beam power tube with a 35Z5 rectifier and a 12SK7 (or other 12.6V pentode or triode). Weren't there also some European countries (or parts thereof) that used various DC voltages for lighting and small appliances? (Belgium or Italy?). Another artifact of earlier days in US industrial applications is 55/110/220/440V 25 Hz distribution. The power transformers are huge and the "hum" is more of a "rattle". --Chuck

On 01/02/2011 11:22, Christian Corti wrote: Both TN-C and TN-C-S are allowed here, but those terms refer specifically only to building wiring, and where the neutral is connected to earth (as it always is, somewhere). But Tony was writing about appliance wiring, and he's right about that; the protective conductor is not permitted to carry any load current under normal conditions, whether it's a fixed appliance or portable. -- Pete Peter Turnbull Network Manager University of York

That sounds right, but I would have to get the data books out to check. US valve numbers have absolutley no logic to them... I don;t think there was a UK version of this valve. We had a range of vavles with 100mA heters, but te rectifier (UY85) and output pentode (UL84) had heterrs around 40-50V. There was a 50mA range of valves (VY2, VCL2, ertc) but they were only used on the continent. Cheap record playes over here tended to use the turntable motor widing and an autotransformre to run the valve heaters (series string totalling around 100V) and get the HT (B+) by half-0wave rectifying the mains. Right... We had DC mains in England into the 1950s in some areas. A lot of radios and TVs weew 'AC/DC',not just to save the cost of the mains transformer. I rememebr working on TVs (long after the 1950s, of coruse) with different voltage selector settings for AC and DC mains (possibly due to fact that the smoothing capacitor would charge to the peak and not the RMS votlage of AC mains). One of the Mullard books of audio amplfiier cirucits (including things like the 5-10 and 5-20) includes a circuit for an amplifier (4 valves, something like UF86, 2 * UCL82, UY85) for AC/DC mains. Of coruse it was hot-chassis which is a right pain... DC mains was somethign of a pain too. It was not smooth DC. It came from commutator-type generators and had a lot of relatively high frequency (audo band) ripple/noise on it. Non-triival to keep out of audio amplifiers! Even if the mains was AC, it wasn't necessarily 50Hz. I think all sorts of other frequencies were used in some areas at some times. Certainly Lynmouth (north Bevon) had 100Hz mains until the hydro-electric power station was destroed in the floods of 1952. -tony

On 1 Feb 2011 at 16:49, William Donzelli wrote: In my younger days, I worked at Inland Steel in various plants and departments. There were three power distribution frequencies in use; DC, 25Hz and 60 Hz. The 25Hz was generated locally from waste heat; the 60 Hz was purchased and the DC could come from either source (via large rotary converters). The DC made sense as it was used for the overhead cranes (and electromagnets), traction motors as one might find on an ingot buggy, welding and for the large motors that powered the rolling mills. Since the 25Hz was the cheapest power source, it was used for lighting, ventilation, running various control instruments and as general utility. A side effect of this was that new equipment was being ordered at a significant premium to make use of 25Hz. My tenure occurred when the plants began shifting from incandescent to mercury vapor lighting. While the incandescent lighting had a distinct pulse to it on 25Hz, the mercury vapor flicker was probably sufficient to induce a seizure. --Chuck

On 01/02/2011 18:53, Tony Duell wrote: The RCDs on the supplies into our data centre are settable; they can be set at least as low as 30mA but normally they're set to over an amp and can be set as high as 6.3A residual current. What's allowed depends on the context (and that includes the time they take as well as the current). -- Pete Peter Turnbull Network Manager University of York

On Monday, January 31, 2011, Richard wrote: You mean 230cm and 240in. Geeze, get it right. Pat -- Purdue University Research Computing --- http://www.rcac.purdue.edu/ The Computer Refuge --- http://computer-refuge.org

Does it matter what colour the plug is? -- ------------------------------------ personal: http://www.cameronkaiser.com/ -- Cameron Kaiser * Floodgap Systems * www.floodgap.com * ckaiser at floodgap.com -- Anything that can be put into a nutshell belongs there. -- F. G. Brauer ----

Yes, we had those over here too... The battery-only radios would use 4 valves. The later series (25mA filaments) were DK96 (pentagrid frequency changer), DF96 (IF amplifier pentode), DAF96 (detecotr diopde and audio pentode) and DL96 (output pentode). The last had a pair of filaments that could be wired in series or parallel. Theser were directly heated valves, 1.4V per filament. In battery-only sets. all 5 filament secions were wiredf in parallel normally. The LT (A) supply was a 1.5V battery with 2 or 4 cells in parallel. The HT (B+) supply was a 90V (noemally) layer battery. The filaments had to be run off DC of course. So the mains/DC models put all the filaments in series for a total of 7.5V, and put baalsat resistor around bits fo the chain to compensate for the fact that in a directly heated valve the anode currnet passes through the filament (and with such low filament currents it did matter). For abttery operation, the LT supply was a 7.5V dry battery. For mains operation, the filament string was run throug ha dropping resistor from the HT+ line, and the latter was nomrally supplied from the mains via a dropping resistor and selenium rectifier. There were exceptions. I have an old Vidor battey/mains portable that does much the smae thing with the filaments (in series, run off the HT+ line in mains mode), but the HT comes from a trnasofemr and valve (EZ40 IIRC) rectifier. Tht at leat means it's not live-chassis. -tony

On Wednesday, February 02, 2011, Tony Duell wrote: Yes, I mean 200A. When you're dealing with high-ish voltage (277V to ground), and lots of power being used (about 1000 amps per phase), leakages can add up quickly... And, it's most likely a spike, not a continuous leakage current, eg, a short-lived arc to ground from some worn out insulating parts. In any case a 200A short-term fault isn't all that huge. Ratings for typical US house circuit breakers are around 10,000A interrupting capability. Pat -- Purdue University Research Computing --- http://www.rcac.purdue.edu/ The Computer Refuge --- http://computer-refuge.org

On Tue, Feb 1, 2011 at 4:51 PM, Brent Hilpert <hilpert at cs.ubc.ca> wrote: It's a commercial dish washer that's actually hooked up and running in my kitchen now. I installed a subpanel and ran a separate 30 amp 220 line. It works great. I was just wondering whether it would work on european power. brian

On Thursday, February 03, 2011, Tony Duell wrote: Yes. Things would have heated up quickly and/or blown fuses if it was long-duration. Yes, it's high. I'd agree. The problem is convincing people to spend the time tracking down an intermittent fault somewhere within more than a dozen possible pieces of equipment. Sometimes it's easier to just wait for it to go BANG!, and pick up the pieces. There's nothing irreplacable or unique that it could destroy, and the equipment is generally designed to contain such a problem to avoid hurting a person who's nearby when it happens. Yes, I do understand the difference. My point is that a fault that's 200A on a supply that can probably supply a fault current nearing 100kA, isn't that big compared to what's possible, (eg, not a "dead short"). And for whatever it's worth, unless it's a special purpose breaker, a circuit breaker doesn't trip as soon as the current crosses its rated current, where "soon" can be as long as minutes depending on the breaker if you're only overloading by 10% or so. I was amazed at how long (10-15 minutes) a particular 20A breaker sustained a 25A load before it tripped. Then again, the thermal response of a breaker tends to match the effects of wires (that it's protecting) to keep them from overheating. Pat -- Purdue University Research Computing --- http://www.rcac.purdue.edu/ The Computer Refuge --- http://computer-refuge.org

I see.. There's never time or money to do it right. nut there is time and moneyu to bodge it when things finally fail catestrophically. And youwonder wheat's wrong with the world... Perhaps you can explain to me the point of an earth-leakage breaker under thsoe conditions... It's nvercurent device (that is, a derive that cuts th emains if the current in the power-carying conductors exceeds a certain value). The normal reason for having them over here is to protect people in the event of an insulation breakdown, the unbalanced current flowing throughj the person to ground will trip the breaker. I doubt that 200A would flow though a person touvhing a live conductor (if it would,then there'd be no point in the RCD in most isntalations, the nromal current-operated breakers would trip). And if it fif, that person would not notice it. Ever. So I am seriosu. What fault is the 200A earth-leakage breaker protecting against? Ture enough. But what fault would trip this breaker nad not a current-operated one? What is it protecting against? The same is true of fuses, of course. A 20A fuse does not melt the instant the currnet rises over 20A. The currnet agianst time (I-t) characteristics of fuses and circuit breakers are specified i nthe data sheets (and at least over here there are British Standards giving hte ones ocmmonly used). It's often important to allow a higher-than-normal inrush current. I am sure we've all used anti-surge fuses, for example. However, I didn;t think that earth-leakage brekaers (RCDs, etc) had much of a time delay as standard. The idea being that there really shouldn't be an earth leakage current, not even fopr a faraction of a second. -tony

On 04/02/2011 19:25, Tony Duell wrote: Yes... the standard circuit breakers used in homes, offices, etc are usually A-curve or (more often) B-curve, but for IT installations (lots of switchmode power supplies) and installations with motors, usually C-curve or D-curve to handle quite long inrush currents. And they're EN standards, so international (sorry, I don't remember the EN number). Usually l about one cycle of the mains, 20ms here (with 50Hz mains), occasionally one half-cycle, though as I may have mentioned when describing our big RCDs in the data centres, those can be set for longer times too: up to one second I think. -- Pete Peter Turnbull Network Manager University of York

On 2011 Feb 2, at 5:51 PM, Brian Lanning wrote: The real-world difference between North American 240V and Euro 240V is the maximum potential relative to ground: NA: 120 VRMS, 170V peak Euro: 240 VRMS, 340V peak Of course, the lower potential to ground is precisely why NA uses the split-phase 120/240: it is much safer for humans but you still have 240 for heavy loads. For equipment, in theory, there could be a problem if the insulation rating of some component (e.g. caps) could not handle the higher potential to ground. In practice, it's somewhat unlikely a manufacturer would build anything such that that would be a problem.

This reasoning sounds really flawed. A jolt of unexpected 120 V AC will certainly make the muscles do uncontrolled things. It is the "uncontrolled things" that cause nearly all the injuries and deaths - things like falling off ladders, whacking elbows against walls, hitting oneself in the face with tools, etc.. -- Will

That's one difference. The other difference is that in the States you have a centre-tap available. They certianly shouldn't. I don't know what your regulations require, but over here I belive it has to be able to stand at least twice the mains voltage between the current-carrying wires and ground. I test everyting at 1000V (and repair it if there's any leakage I can't justify). Note that 'everything' includes brand-new stuff too, and yus, I've had the odd faiulur (in fact classic computing equipment seems to be rahter better than new stuff in this regard). -tony

On 5 Feb 2011 at 17:45, Pete Turnbull wrote: Hmm, you'd think that someone would have thought of powering "universal motor" tools, such as saws and drills used on construction sites with DC as a safety measure. The current level at which one loses muscle control is substantially higher with DC than with AC. Many power tools sold in the US have no 3rd wire for grounding at all, instead, a "double insulated" method of construction is used. What's curious is that such tools often employ the "large blade = neutra, small blade = line" polarized plugs. --Chuck

The most "shocking" thing about getting shocked with house current is not the pain, nor the involuntary muscle movement, but the surprise. Most people never expect to get shocked, and the weird sensation will cause a panic, with the brain thinking "pull out!" and the muscles perhaps not following orders exactly, all with perhaps a little bit of a flash-bang effect - and then the injury happens (falling off ladders, etc.). Look at electricians, especially ones that repair old installations. They get bitten all the time, and they really don't flinch much at all. They are used to getting shocked. 120 V AC really does not hurt much at all, and 240 V is only slightly more painful - and I am not talking about whack your thumb with the hammer pain, here. A fair number of electricians actually test wires with their fingers. It is mostly just a very weird sensation. Get used to it, respect it, and it is not really an issue. -- Will

Get a cordless. -- Will

On 2011 Feb 5, at 2:05 AM, Pete Turnbull wrote: I have heard that argument too, but I'm not at all convinced by it. It strikes me more as 230V system users trying to justify why it's 'better', or 'not less safe'. As someone with direct experience working with both voltages (relative to ground), I'm not fond of being shocked by either level, but I can tell you quite quickly which level I prefer to work around and 'prefer' to come in contact with. It varies between individuals and conditions, but 120V shocks for many are quite tolerable in the sense of it being enough to warn you without producing damage (or as William was pointing out, the difference between 'shock' and 'surprise'). IME, I can't say the same thing about 240. 240 is double 120, by Ohm's law and impedance, lethal currents are more 'likely' or easily produced by the higher voltage. Yes, one always has to be careful around both levels for both shock concern and because there is a fair mount of energy behind both (slipped tools producing big sparks and damage). I'm not well acquainted with the UK/Euro rules history, but I'll put forth that the UK/Euro 110/55 building-site requirements are evidence of the point. It's nice that it actually lowers the V-to-ground to such a low level, but I expect it exists because the 240V-to-ground is considered unsafe, while in NA we get by safely enough with the 120V-to-ground on building sites.

On 5 Feb 2011 at 14:10, William Donzelli wrote: Ever have to pre-drill and drive 500 4" deck screws with a cordless? It can be done, but you'd better have a pile of charged batteries. Battery-powered circular saws are also a joke--I've yet to see one that could hold its own against my worm-drive Skilsaw. I have several cordless drills and drivers, including hammer drills and impact wrenches. They're okay for small jobs, but don't hold up under heavy use. (Much like trying to mow the meadow in front of my house with a cordless lawn mower...) I've also popped the power FETs in a couple of cordless drills after heavy use. They probably gave out because their cooling mostly consists of having a small heatsink in a confined space--but stupid design is a completely different topic. --Chuck

On 2011 Feb 5, at 11:06 AM, Chuck Guzis wrote: Remember old (pre ~1970) power drills? : non-polarised plug, ungrounded, and *aluminum* housing and handle. Some might think some of the safety rules these days are overkill, but when you look at the way a lot of old stuff was built you see the other side.

On 5 Feb 2011 at 17:08, William Donzelli wrote: I don't believe it. If that were the case, the contractors around here would be gobbling them up like hotcakes and nobody would own a corded saw or drill. Got any figures for how much 4x fir a modern cordless circular saw will rip (not crosscut) on a charge? I'm prepared to be proved wrong, but if a 7" cordless saw can cut a shift's worth of framing lumber on a single charge, I'll seriously consider buying one. --Chuck

On 2011 Feb 5, at 7:27 AM, Tony Duell wrote: ? The centre-tap is there as an outcome of the design, not innate intent.

On 2/5/11 3:32 PM, Curt @ Atari Museum wrote: You can image them, but machines after OS 8 can't read the earlier MFS disk format. http://guides.macrumors.com/Mac_OS_%28Classic%29 Mac OS 8 * This was the last system to support reading from the MFS. Creating MFS disks had been dropped in System 3, when MFS was replaced with HFS. There is also a problem where early Mac apps get confused with aliases. Forget when that occured, probably when aliases were added.

--- On Sat, 2/5/11, Curt @ Atari Museum <curt at atarimuseum.com> wrote: The PowerMac will. System 8.1 will not. They dropped support for 400K disks in System 7.6. So, you'll need to have 7.5 or older installed to read data from them. IIRC, DiskCopy will still make images of the 400K disks, even though the OS won't read them. -Ian

Hi, Just wanted to thank everyone again for the assistance. I installed System 7.5.3 and viola! I was able to read the diskettes (most).... One diskette (Corvus User Client) isn't reading for some reason... I tried Norton Disk Doctor 3.5 and it read the drive label and saw it as "Corvus User Client" but said it didn't support repair/verify of non-HFS disks so I got a little closer, but not close enough... So I'll have to find a disk repair tool that works with older 400k diskettes so I can run a repair/fix on it and get it fully readable. Well, the good news is that 4 of the 5 disks were readable, I moved them over to my server via Appleshare and just posted up a quick page (I'll clean up the disk images later on, but just posted up the scans of the disks and then linked them to .ZIP images of the contents of each diskette (no apple imaging, straight files copy and then zipped up the directories I had made) http://www.corvusmuseum.com/software/mac/ If anyone has any Corvus diskettes and wants to contribute to the archive project, please email me off-list, thanks! Curt

On Sun, 6 Feb 2011, Curt @ Atari Museum wrote: Why not guitar or piano? ;-) Christian

And some things only have 2-pin mains conenctors :-(. I wonder how they comply with the EMC directives.... actually, plenty of my classic machines don't have mains filter modules. They have spearate capaxcitors and indcutors on the PCB. I prefer that -- easier to repair. -tony

The peak voltage from the power-carryingwires to ground is also an outcome of the design. My real point is that no device that requires 220V should care about the voltage to ground (within reason). I would certainly consider a 220V device that could not satand 220V between one of the power-carrying wires to ground ans being unsafe. But as various people have pointed out, many US 220V appliances do use 110V for something (controller, timer, etc). That's a bigger problem when running them in Europe Actualyl, I have amn instrument (I think it's my Tektronix 575 curve tracer) whic hahs sepprate wiring arrangements for 115V, 230V with the centre earthed and 230V with one side earthed. No, the last 2 are not a safety thing. Appranetly by having certain points of the transformer primary close ot ground you get slightly less noise in the instrument. -tony

On 6 Feb 2011 at 15:54, Tony Duell wrote: I On the subject of plugs and receptacles, quite a number of professional building contractors around here use 3-prong "twist- lock" aka "Hubbel" connectors for their corded tools. One advantage is that the plugs won't simply pull out. The twist-lock connectors are also quite common in things such as RV hookups and portable generators and can be had in various sizes of 3 and 4 prong versions. They were quite common in comptuer data centers, but I don't know if that's still true. --Chuck

On 2011 Feb 6, at 8:07 AM, Tony Duell wrote: You're obfuscating. The point of your comment remains a mystery other than being to find something to comment on. At this point, no, I don't want an explanation. Yes, good design would say that it shouldn't matter and I can't say that I've run across a device where it did matter. But I'm not about to tell someone working on a device I'm not acquainted with that they never will. Hence my use of the word 'unlikely' in the earlier message.

Yes, extension cords at construction sites tend to take a tremendous amount of abuse, getting run over, yanked, chopped, abraded, and stolen. Twistlocks help. Generally, yes. I think there is a move away from the older R&S style connectors of the big mainframe era. Which is good for us, because the latter are EXPENSIVE (especially the ones for 400 Hz power). -- Will

Blue Ribbon was the name of the product line, and covered quite a few styles of connectors. -- Will

I don;'t dispute that for an instant. What I do disagree with is that all pre-1970 power tools in all countries wire not earthed nad wired to non-polarised plugs. This is an international list after all. -tony

On 6 Feb 2011 at 20:28, Tony Duell wrote: Aren't PL/SO-239 coax connectors still called "UHF" connectors by some? That comes from a time when anything above about 30 MHz was "UHF"--and anything above 300 MHz was "microwave". --Chuck

Harder to hold with your chin and use a bow on?

No, those threaded things form a diverse family, and go under the names of AN3100s, MS connectors, and so forth. The old R&S connectors are the big "pin and sleeve" types, with older models in metal enclosures. The new ones are plastic, color coded, and in the UK are called "Commando plugs". They are often seen at marinas, as they are available in water tight enclosures. Originally AN310x, with x signifying straight/angle/chassis/cable options. The system was formed around 1941 (I think), in order to standardize the US military's connector situation. Those three pinners in various sizes are quite common. -- Will

On Saturday, February 05, 2011, William Donzelli wrote: Indeed. After making sure i'm well insulated, I like to brush the terminals of the circuit I'm working with the a knuckle, to make sure it's de-energized. My fingers are very unlikely to fail at telling me if there's some voltage there... Pat -- Purdue University Research Computing --- http://www.rcac.purdue.edu/ The Computer Refuge --- http://computer-refuge.org

From: Curt @ Atari Museum Sent: Sunday, February 06, 2011 10:11 AM Christian Corti wrote: Softly, now! Rich Alderson Vintage Computing Sr. Server Engineer Vulcan, Inc. 505 5th Avenue S, Suite 900 Seattle, WA 98104 mailto:RichA at vulcan.com mailto:RichA at LivingComputerMuseum.org http://www.LivingComputerMuseum.org/