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Thread: Minicomputer power draw?

  1. #1

    Default Minicomputer power draw?

    I'm curious, how much power would a small minicomputer setup (say, the CPU/memory and a couple disk drives) consume? I guess that's probably something that varies by model and setup, but is there a general ballpark value per hour/day/whatever?

    Just wondering.
    Computers: Amiga 1200, DEC VAXStation 4000/60, DEC MicroPDP-11/73
    Synthesizers: Roland JX-10/SH-09/MT-32/D-50, Yamaha DX7-II/V50/TX7/TG33/FB-01, Korg MS-20 Mini/ARP Odyssey/DW-8000/X5DR, Ensoniq SQ-80, E-mu Proteus/2, Moog Satellite, Oberheim SEM
    "'Legacy code' often differs from its suggested alternative by actually working and scaling." - Bjarne Stroustrup

  2. #2

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    Heh, not sure I want to know this answer. I'm sure the power company loves me when I fire up the PDP-11...
    We discuss retro computers of all shapes and sizes on the Retro Computing Roundtable (RCR) Podcast. Listen in at http://rcrpodcast.com.

  3. #3

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    That's exactly what I was thinking, bet minicomputer hobbyists have a fun time with this...
    Computers: Amiga 1200, DEC VAXStation 4000/60, DEC MicroPDP-11/73
    Synthesizers: Roland JX-10/SH-09/MT-32/D-50, Yamaha DX7-II/V50/TX7/TG33/FB-01, Korg MS-20 Mini/ARP Odyssey/DW-8000/X5DR, Ensoniq SQ-80, E-mu Proteus/2, Moog Satellite, Oberheim SEM
    "'Legacy code' often differs from its suggested alternative by actually working and scaling." - Bjarne Stroustrup

  4. #4
    Join Date
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    I have my own separate kilowatt meter that monitors all the power being used in my workshop. You don't want to know what it reads after a year of service. :P
    My 11/84 it a fairly average configuration and uses no more than 700 watts but the current draw on the RA82 is another story. At spinup it will dim the lights.
    = Excellent space heater

  5. #5

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    Depends greatly on the machine. The "micro" PDP-11's draw relatively little power. When you get into the larger boxen, it goes up... A MicroVax 3900, with two RA90's and a console terminal uses an entire 15A circuit, to the point where much more will blow it. I've got other machines where I run the CPU on one circuit (20A) and the disk/tape drives on another.

    If you want to run it continuously, you're going to use a lot of juice. I did that once, and found that it is very possible to make your electric bill go up by $200 with one single computer.

    Of course, when you get into the bigger systems, you need at least 240, or three phase. Fortunately, most machines designed for three phase can be modified to operate on 240.

    -Ian

  6. #6

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    I have the beefiest UPS I could buy at my local computer store on my PDP8e with twin RK05 drives. The UPS beeps a warning bell for a second or two when I power on the system, and then calms down enough to appear to be ok after that. I wanted the UPS to regulate the power coming into the system and to give me a few seconds to power down if the house power died. So far this arrangement seems to be fine. My PDP 11/40 by itself does not appear draw too much, nor my 11/05. It seems like the 8e is worse with the two disk drives. I am guessing I am hitting 12 amps.

    Any opinions on whether I am unknowingly taking a risk?

    Bill
    @ BillDeg:
    Web: vintagecomputer.net
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  7. #7

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    Of course there's nothing like actually measuring it. When the price got down to dirt cheap (compared to before) I couldn't resist and I bought a clamp-on meter like this one. That's an overpricie store, so I'm sure there's cheaper. Then I took a 3' piece of 14ga cable and put some heavy duty male and female AC connectors on the ends. With a pullout loop of wire in the middle it's an easy way to measure fridges, computers, what have you. Having a realistic number certainly gave me some peace of mind as well as satisfying my curiosity.

    Of course most cheap multimeters will measure higher amperages these days, so if you make a breakout chord with that configuration you wouldn't actually have to buy a second meter.
    WANTED: Cardinal 2450MNP modem.

  8. #8

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    Quote Originally Posted by Ole Juul View Post
    Of course there's nothing like actually measuring it.

    Of course most cheap multimeters will measure higher amperages these days, so if you make a breakout chord with that configuration you wouldn't actually have to buy a second meter.
    well yah, that.
    @ BillDeg:
    Web: vintagecomputer.net
    Twitter: @billdeg
    Youtube: @billdeg
    Unauthorized Bio

  9. #9
    Join Date
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    Chandler, AZ, USA
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    I use a Kill-a-Watt EZ meter.
    http://www.homedepot.com/buy/electri...att-83064.html
    You can even enter your electricity rate, and it'll tell you how much it's costing per hour/day/week/month.
    At $ 20 I figured it was a pretty good deal.

  10. #10

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    Quote Originally Posted by Lorne View Post
    I use a Kill-a-Watt EZ meter.
    Just a word of warning, the Kill-A-Watt does NOT like being subjected to devices with a current draw greater than fifteen amps.

    Ask me how I know that

    -Ian

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