At the old small office I would just pop some breakers out and replace them with 2 pole 30 amp ones. When it was at the hackerspace there was some sort of fused cut off switch box on the wall, so I terminated a twistlock 30A and ran from there over to a subpanel that had the 3 twistlocks for the Cray cabinets. I used A-B B-C C-A phases, so 208V each. I still have the subpanel and also a SquareD Powerlogic monitor w/ CTs and stuff that are mounted to the board that was with the system (might be visible in the picture.) I used a rubber core cable to run between the two -- which I originally had picked up to temporary run a 6 watt argon laser system with from time to time. I originally had 4 of the J932SE systems, they were all HIPPI'ed together to form one system when used for power engineering for nuclear subs or something (Bechtel.) I dunno, it was all secret and they destroyed all of the hard drives and such from the system. I never really thought the power was that crazy, I work in datacenters and these days there are single racks using twice what the Cray takes! Very cool! NASA LaRC had a J916 system used by some scientists for something, other than that I don't know of any others. I was a SGI guy at the same place, had some nice boxes.

On Tue, 19 Jul 2016, Paul Koning wrote: With respect, in my view, it's not trivial. As you point out, it's not actually allowed everywhere. Unless you are some kind of local townie who knows all the bylaws, you'd need to call your local building/permitting office to be sure. I've lived in several places where it was definitely not allowed. In (al)most all places, you also need a permit to do the work, even if the PtB let you do it as an unlicensed hobbyist. Also, any given rinky-dink home electrical panel box isn't always going to support 30A breakers, might be out of room, or might not magically grant you the service-line current you may require (or in the case of 3-phase, the third phase you are going to need). You'll also need to find a route to get the proper sized wire in to the walls to feed the L6-30 or whatever receptacles you need, and install the outlets. That's real physical work in my book and may non-trivially eat your weekend. The other thing that's not trivial is that if you make a mistake, you will likely either: 1. Die. 2. Burn down your house. 3. Ruin some expensive and rare gear. To me, that all sounds like a helluva pain and != trivial. Then again, I'm a software guy. What do I know? :-P -Swift

Also, know your own limits. A depressing number of people think they're more competent than they are. For example, I once had a neighbour who replaced an outlet in his kitchen. Turned off the breaker, removed the old one, put in the new one, all very nice. Turned the breaker for that circuit back on and popped the service main breaker. When I investigated, it turned out the new outlet still had the bridging piece that shorts together the hots for the two outlets, and this was a kitchen outlet and thus had separate circuits for each half (and, as is often the case, they were on adjacent fingers in the breaker box and thus on different phases). So, of course, the new outlet shorted the two hot phases together. He didn't have the experience to recognize that those shorting pieces exist, to realize that having four conductors instead of three coming to the outlet - or its being a kitchen outlet - likely means the two halves are on different circuits and thus likely different phases, or the electrical understanding to put those facts together. Which wouldn't've been a problem, except that he thought he was fine - he didn't bring me in until the main service breaker blew. (He did, fortunately, have enough sense for that to tickle his "something I don't understand happened, call for help" reaction.) I've been doing electrical work since I was maybe ten or twelve, when I helped my parents wire the house they were building. (My father inspected my work first; then, this being de rigeur there-and-then, it was inspected by a suitable authority. Only then was it energized.) I don't hesitate to do routine house electrical work, maybe even installing 30A outlets (though I'd make sure I looked up the appropriate gauge of wire, and probably then used the next larger gauge). But I'd call in someone more experienced for something well outside my own experience, like (say) dealing with 600/600 service. I would say that, if you don't have a good deal of experience, find someone who does to look over your work before you energize it. Indeed, some jurisdictions require that for work done by unlicensed persons - or at least used to, and I would assume some still do. Even if yours doesn't, it strikes me as the smart thing to do. /~\ The ASCII Mouse \ / Ribbon Campaign X Against HTML mouse at rodents-montreal.org / \ Email! 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B

Three phase power shows up in a bunch of places. Some high current power supplies (pre switching era) use three phase input to increase the ripple frequency and reduce its amplitude, which significantly reduces the size of the required filter capacitors. I remember that in the KL-10. CDC 6000 mainframes go further, not only using 3 phase but also 400 Hz power for that reason (that also shrinks the transformers). Cooling systems might run on 3 phase, or not. The compressors in the 6000 series CPU cabinets are 3 phase motors. But the DD60 display uses 3 phase power only for the high voltage power supplies; the cooling fans are run off 230 V 60 Hz single phase. If I remember right, the RP04 uses 3 phase power for the spindle motor. Probably not for the logic power, though. paul

On Tue, 19 Jul 2016, Paul Koning wrote: My original point was that it's not trivial. I'd stand by that point no matter how comfortable someone is with the install. Of course, even that is subjective, I suppose. If you have tons of time, money, and you were born with rubber duck feet, okay, sure, it's trivial for that particular human-duck hybrid. :-) My real point is that if someone thinks they are just going to un-do a few screws on the breaker panel, slap in a 30A breaker, and they are done: that's not realistic. That's kinda how using the word "trivial" struck me along with the original description, at least. Maybe I'm over-thinking it. Perhaps it wasn't obvious, but I've also done this type of work myself before, IRL. I choose not to use as much jargon, but that does not mean I'm speaking about hypotheticals. Personally, I don't need the Amazon book, though others might appreciate that. Again, I wasn't saying, "OMG, that's impossible!" My points were, simply "It's not trivial" and "It's a tad bit dangerous to trivialize it.". I think most able-bodied folks would have the "muscle" to do it. It doesn't require winning any strongman competitions. No matter if you are a skinny little waif like me or some bodybuilding strongman, as I'm sure you all are. The issue I was bringing up wasn't despair at the inhuman physical strength required (joke!), but that it's going to take time, energy, and money... ie... subjectively non-trivial resources. To your point, it's definitely going to be cheaper to do it yourself versus using a licensed electrician, and it's not black magic. Fair enough, but there isn't as much of a chance for instant-electrocution-death involved with plumbing and carpentry. Putting in 3-phase 208 isn't rocket science, but it can definitely kill you, burn your house down, or ruin your gear if you do it wrong. Of course, plumbing and carpentry done wrong could eventually flood your house or cause it to fall down in some extreme cases, too. The results just *usually* aren't quite as immediate and dramatic as electrical mistakes are. To your point, I'm quite the opposite. I'm a woodworker and setup to do just about any kind of carpentry imaginable. I don't have the butt-crack power (or the slightest detectable will) to properly plumb, that's for sure. When it comes to electrical work the issue is often permitting and inspection that are a problem in my area (building boom etc..) that makes it non-trivial. That and dealing with Xcel Energy, who could probably screw up a wet-dream, for the feeds. Agreed. Yeah, that's sort of my underlying point. While it might be easy to some people in terms of them not feeling intimidated by the task, it still will take some time, effort, money, and risk to your person (small or large depending on your levels of caution and experience). -Swift

On 07/19/2016 08:29 AM, Paul Koning wrote: A big concern would be getting basic service. I'd probably want a secondary 200A panel for this, so the local utility would probably drop a second transformer in my front yard (there's buried 12KV service running up my driveway). At least getting the extra panel would involve a licensed electrician and inspections. What would be a bigger concern is any HVAC needs. The EPA has been getting very predatory in their regulation of refrigerants and who is qualified to handle them. New proposed regulations are even more stringent. Life is very good if you're a licensed HVAC tech today. --Chuck

This, I believe, must be location-specific. In North America, it is usual for domestic electrical feeds to be only two-phase (that is, they are the two sides of a centre-tapped secondary - the two hot wires are 180 degrees out of phase with one another). /~\ The ASCII Mouse \ / Ribbon Campaign X Against HTML mouse at rodents-montreal.org / \ Email! 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B

The Cray is single phase, the only thing I've ever owned that was 3 phase was the laser stuff. Now my solid state laser projector uses 100 watts and producsed half the power of the argon that used to take 3ph @ 30A (and still tripped the breaker sometimes.) I've heard sometimes the utility will indeed give you 3phase but you have to pay them to replace the transformer and it's very very expensive. Normally it's people buying used milling equipment that are after it from my experience. There are rotary converters and solid state converters but probably not ideal for huge loads. The Cray uses 5 x Pioneer magnetics power supplies that I believe are identical to those in the Sun E10000. The smaller rack with the VME chassis and hard drives -- good chance the power supplies are okay with 110/120v. The disk trays at least are just good quality SMPS that do 5/12 in each drawer (was 4 x 9GB full height disk per drawer.) The Pioneer Magnetics supplies that run the computational part are like 48vdc out @ 5000W each.... so not sure if they would run on 120V but if so -- it would be a real high amperage load. Note - in the modern datacenter in the US it's not uncommon for everything to be run on 208, but everything would run on 120. -- Ethan O'Toole

On Tue, 19 Jul 2016, ethan at 757.org wrote: I haven't been able to articulate anything witty, but I'll go ahead and just say: Ethan I don't know what you do with those BF-lasers, but it sounds damn awesome, anyway. Your stock just went up. It's hard to make lasers anything but sci-fi radical coolness. Yep. It's happened in every case I've been involved with here in Colorado (ie.. residential or small buildings, not in data centers). ... and as I mentioned before, they can break. So, even if your VCF will handle the load, your uptime requirement might be a dealbreaker if you have commercial intentions. "back in the day" I was a certified (not as an FE, though) in various ways for the E10k, E15k, and E25k. We had several at Oracle when I worked there. However, I don't remember that detail (the brand of the PSs). I'm sure you are right, though. Yep, that's my experience, too. Although many telco datacenters still use DC. They are funny like that. -Swift

On Tue, 19 Jul 2016, Paul Koning wrote: I forgot about those. I think you are right. I've seen what I believe to be massive VCFs in a metal-powder mill with multiple inputs. Those probably can provide you with even more redundancy since you can run multiple input lines. -Swift

On Tue, 19 Jul 2016, ethan at 757.org wrote: Killer. I wish we were neighbors, Ethan. We'd be able to throw the most awesome block parties, I swear. I bet you are a musician, too. Huh, cool! That sounds (and from the videos also looks) fun. Neat. What fun! Okay, after talking about the recent roots of that hobby, and in an effort to keep this slightly on topic, do you know anything about the original animations used on Freemont street in Las Vegas? I was told that at one time it was run from an Amiga using Scala "and some other stuff". If you haven't seen it, it's a giant (uhm, like 4 city blocks) color LED array and a big sound system. -Swift

They generaly use mirrors - I would cobble something together by taking the laser diode read head from a CD rom, and removing the diode assembly, and glue a small, thin, front surface mirror in its place, and drive the coil from the output of an audio amp, just to try it out. A pair of these, at right angles, would give you X/Y deflection. Karl ----- Original Message ----- From: "Mouse" <mouse at Rodents-Montreal.ORG> To: <cctalk at classiccmp.org> Sent: Tuesday, July 19, 2016 4:02 PM Subject: Re: LASERS! && Freemont Street LED array (was Re: Cray J932SE (was Re: Straight 8 up on Ebay just now))

What bandwidth (deflection rate) do you need? Full scale in a microsecond? In 10 microseconds? Piezoelectric loudspeakers work up into ultrasonic range. A mirror attached to such an actuator would give you variable deflection. So 10 microseconds might be doable. A faster (no moving parts) scheme might be to use Kerr cells. I don't know if that has been done, but from what I understand about the Kerr effect it seems plausible that it could be. paul

In my day job I work on computational holography and other forms of esoteric 3D displays, so I can give you some insight in how these things work. Remember these are vector displays and not raster displays, so the computational side is not an issue. You are basically looking at a pair of D/A convertors that are driven by a pair of parallel ports. The circuit is probably a bit more complicated than that, but you get the idea. This can be done interactively with no problem. With a modern CPU you are probably looking at less than 1% of the CPU time. The complication occurs with the lasers and the optics. For an outdoor display you need a very high power laser, which will literally melt standard optics devices. There are special lens and mirrors that are used with high power lasers, look at Edmund Optics. The deflection range is relatively small, around 1 degree. The limiting factor is how fast you can move the mirror, which depends on mass and inertia. With these small deflections you can get pretty high rates. Indoors with low light you can get away with much lower power, 10mW is more than enough. With this power level you can use standard optics, and the lasers are quite cheap < $30 as long as you like red. I've heard of people using TI DMDs to deflect laser beams. Even the low end DMDs can display 1 bit raster images at 4000Hz. One of the problems with this technology is it's hard to modulate the laser intensity, which greatly restricts the range of colours you can produce. -----Original Message----- From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Mouse Sent: July 19, 2016 4:47 PM To: cctalk at classiccmp.org Subject: Re: LASERS! && Freemont Street LED array (was Re: Cray J932SE (was Re: Straight 8 up on Ebay just now)) Well, if it takes longer than 100ms to replot the display, it will flicker visibly, and the more under 100ms the better. In that time I'd like to draw at least a couple hundred lines, though most of them will be short (line length maybe 1-15% of corner-to-corner distance). What kind of radians/second deflection rates this means depends on how far from the wall you put the projector. But, in terms of the bandwidth on the X and Y axis signals? If we say 200 lines at 25 ms replot (I get 20ms frame rate out of the cg6 for displays significantly more complex than that - ie, with the cg6 the actual limitation is the video signal vertical frequency), that's 125us/line. Turning sharp corners is the hard part with mechanical deflectors like mirrors, as it means very high acceleration of the mechanical parts. I haven't done the math to be sure, but, until/unless taught otherwise by testing, I'd feel dubious about clipping the X and Y signal bandwidths at anything lower than ~1MHz. /~\ The ASCII Mouse \ / Ribbon Campaign X Against HTML mouse at rodents-montreal.org / \ Email! 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus

I don't know a lot about data transmission, my main application is display. The mathematics behind data transmission and display are similar, they are based on wave propagation and diffraction and lots of Fourier transforms. The laser power is not overly important, it's the resolution of diffraction pattern or hologram that you produce. It's a very redundant coding scheme, so part of the signal can be lost and you can still recover all the information. -----Original Message----- From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Swift Griggs Sent: July 19, 2016 6:04 PM To: General Discussion: On-Topic and Off-Topic Posts <cctalk at classiccmp.org> Subject: RE: LASERS! && Freemont Street LED array (was Re: Cray J932SE (was Re: Straight 8 up on Ebay just now)) On Tue, 19 Jul 2016, Mark Green wrote: Holography is amazing. Do you know much about so-called "free space optical" data transmission? I worked with some gear a few years ago that could transmit & receive using multiple lasers at 1Gbit. I was fascinated with that stuff, but the vendor had their folks do all the alignment and installation. So, I didn't get to work with it much. I wonder if you've seen faster speeds than that. I also wonder what the power levels look like for those lasers and what distances the really serious ones can reach. Can they still work in bad weather? It seemed like the ones that I mentioned, still worked in the rain. -Swift PS: It was the May 1984 National Geographic cover that blew me away and made me forever respect holography. :-) --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus

On 19/07/2016 21:46, Mouse wrote: If you want to experiment, you might try to find the mirror/coil assemblies from a Pioneer laserdisk player or similar. They consist of a small mirror mounted on a moving coil so as to turn on one axis through an angle of some +/-10deg (total 20deg). They're light enough to respond somewhere in the kHz (maybe 10s of kHz) range if you only need small deflections, rather than the full 20deg. I've got one here, but never got round to trying it out. -- Pete

On Tue, 19 Jul 2016, ethan at 757.org wrote: I knew it! Piano, bass, violin, and guitar, here. I play them all badly but guitar a little less badly. I've been an amateur for about 10 years and I've been taking guitar lessons for about three years, now. Sax, eh? Cool. I've never tried a reed-based instrument. You have all the cool sound gear you need if you have an ST and a machine with a GUS! Well.... maybe an Amiga with Octamed or Protracker, but Scream Tracker and Impulse Tracker also rocks fairly hard with a GUS, so never mind. :-) As you can tell, I like trackers. I wrote a few MOD/IT/S3M files "back in the day". Ah... I finally found some mention of it. Check this out: "The light and sound spectacular runs on a master show controller and three sub-systems. The controller runs Stage Manager 3000 software on an Amiga computer originally installed when the show began in 1995. Murphy said the master controller sends commands to the video-display controller, light console and digitally automated audio system. The audio system, a recently upgraded LCS Matrix 3 system, distributes 550,000W of sound through 220 remote amplifiers located throughout the outdoor mall." From: http://www.signweb.com/content/night-lights I did know some of that story, but not all. That's really cool. Whoa, very neat. When I was in college I used to run shows out of an old machine shop in an industrial part of town. It started as just a practice place. However, I knew a bunch of artists. They weren't just other college kids but artists who are pretty well known in the area and responsible for large public works etc... They all had daughters, you see... Anyhow, they talked me into letting them setup some art "openings" at this same little dinky venue I had going. One of them was an electrical engineering student who would come up from Texas Tech and cover the place with LED matrices that he had built. It was really impressive tech for the 1990s. He could do things like color cycling, and display static frames, but not animation. It always brought in lots of folks (200-800 per show usually) who were impressed by our tiny art shows with the "Light Room" display. People gave canned food or $$$ to get in and we raised a bit of food and money for charity that way, too. -Swift

On Wed, 20 Jul 2016, ethan at 757.org wrote: I'm not a keyboard guru like some on the list, but I've owned a Roland FP-9 and Alesis DG8. Now I use a Yamaha Clavinova. I miss the DG8, but I traded it off once it's internal amp started fritzing out. I had a friend with an Atari 800XL and I was very impressed with it. I remember a few demos (one with a metallic rendered robot walking toward you, I remember was most impressive). I was surprised that it was just an 8bit machine. At first I thought it might have been 16 bit! The only ones worth using that I'm aware of are Scream Tracker and Impulse Tracker and neither was around in the 16 bit ISA days pre-386, IIRC. I doubt Scream Tracker would be able to function on a 286 anyhow. It puts a 486DX2/66 at about 50% CPU load, from my recollection. The Amiga trackers were more efficient, but you got fewer channels, too. OctaMED was 8-channel and that seemed massive until it wasn't. Yes! I almost forgot about Composer, that was another good one. Several made it there over the years. I can't remember which ones, but I do remember one day I was listening to Nectarine Radio and heard one of my own Protracker MODs. That was awesome. He was just showing proper street cred. +1 Deadmou5 It took some extra hard Googling to find anything about it. The only time I'd even heard about it was when I was actually in Vegas working as a Def Con goon. Ahhh, those air-car-mounted-on-hydraulics "ride" thingys? Huh. Laser disc was always a cool thing, too. Remember "Time Traveler" ? That "holographic" (it wasn't really but it looked damn cool) game were the characters appeared in front of some kind of curved mirror volumetric display uhm, thingamabob? It used a Laserdisc too. Of course I loved Space Ace and Dragons Lair along with every other self-respecting geek, too. Also, my favorite was called "Thayer's Quest" in which you were a wizard's apprentice. Most commercial real estate weasels think you are the next "sucker" coming through the door. They seem to believe that some old crufty warehouse that's been empty for a decade is actually worth the ridiculous rents they charge. You'd think it'd be better to have the buildings occupied and someone giving you a bit or two to cover the property taxes, but they still don't seem to see their clients as anything more than walking cash registers. It's definitely a hard slog to find a screaming deal on space. All the hacker-spaces here in big-D have lots of folks pitching in to make ends meet. The first one here with an Ethan-style laser arcade will definitely get my membership dues. Then there is the problem that nobody but old dudes remember how fun/cool arcades could be, back in a time when they looked a lot more like nightclubs. I remember them so crowded you had to go out for some fresh air. Flynn's Arcade may never live again, but it's still a paradigm of cool in my mind. Then again, I'm probably too old now to adjudicate "cool" for anyone. If you do open an laser-illuminated LED-walled arcade, let us all know so we can put you on the cctalk road-trip map. We'll rent a bus in Seattle, and drive to your place (or visa versa). I nominate Fred to run the logistics. I'll drive. :-P -Swift

At 05:13 PM 7/19/2016, ethan at 757.org wrote: No, Brad was not the founder of NewTek. He did do early designs of the Toaster. - John

On Tue, 19 Jul 2016, Paul Koning wrote: and air compressors in automotive shops, maintaining a large tank of compressed air. 3-phase comes in "delta" or "Wye"("Y") some installers don't know the difference! I experienced TWO misdone installations. One was an auto garage, and resulted in high voltage to the 110 outlets, damaging a bunch of minor stuff, such as grinder, space heater, clock, etc. The other was was a PDP installation. After excessive downtime of third party disk drive, the community college had sold it to a neighboring school district, and bought a roomful of PCs. Microsoft PC COBOL and Fortran were crap, but quite adequate for teaching the languages, and it was great to have dozens of machines for students to use without fear of downtime. PG&E (our power company) agreed to buy a new replacement computer, if those involved would go along with the fiction that it had been a lightning strike (NOT common here). The bad drive ceased to be a problem. Everybody was happy, and PG&E got to call it a donation on their taxes.

On 07/19/2016 01:41 PM, Fred Cisin wrote: Oh, it gets much worse. In the US, there is also corner-grounded open-delta, and center-grounded open delta. These have some advantages in cases with mixed house/office/industrial use, but you need to mknow what you have. Corner-grounded open delta has one of the 3-phase wires grounded. This gives you two hot wires. The giveaway is that two-pole breakers (or fuses) are used. You get two 230 V hot wires that can be used for any single-phase appliance. Center-grounded open-delta uses one standard residential transformer, and has a grounded center tap on that transformer. So, the 3-phase hots all look normal relative to each other, but have strange readings to ground. You get two 120 V hot wires, and can run standard home or office equipment from that, with single or 2-pole breakers. And, you can run 3-phase loads from the 3 hots. In most of these cases, the pole equipment is two separate single-phase transformers. These systems are out of favor, but you still run across them in older mixed-use buildings. Jon

Yes, and time dependent as well. I grew up in Holland; in the 1970s, we had 3 phase in our house because we had an electric cooking range. But ours was the only house in the block with 3 phase service; all our neighbors cooked with gas. In the USA, if you're a home owner with a need for 3 phase power, you probably have to get a phase converter. Fortunately those are not hard to get, and solid state ones (variable frequency motor controllers) can be rather inexpensive. I have one for the 3-phase motor on the lathe in the barn. $100 for a 3 hp model, as I recall, though that may have been on sale. VFCs should even work for 3 phase 400 Hz power, just the thing if you have a CDC Cyber tucked away in the basement. paul