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commodorejohn
March 14th, 2012, 03:28 PM
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.

retrobits
March 14th, 2012, 03:59 PM
Heh, not sure I want to know this answer. I'm sure the power company loves me when I fire up the PDP-11...

commodorejohn
March 14th, 2012, 04:08 PM
That's exactly what I was thinking, bet minicomputer hobbyists have a fun time with this...

NeXT
March 14th, 2012, 05:28 PM
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.

RetroHacker_
March 14th, 2012, 06:15 PM
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

billdeg
March 15th, 2012, 07:26 PM
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

Ole Juul
March 15th, 2012, 08:19 PM
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 (http://www.rpelectronics.com/dcl-280-digital-clamp-on-meter-ac-frequency.html). 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.

billdeg
March 16th, 2012, 05:36 AM
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.

Lorne
March 16th, 2012, 07:45 AM
I use a Kill-a-Watt EZ meter.
http://www.homedepot.com/buy/electrical/electrical-tools-accessories/kill-a-watt-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.

RetroHacker_
March 16th, 2012, 08:58 AM
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

Lorne
March 16th, 2012, 10:48 AM
Ask me how I know that :)

-Ian

Because you read the sticker on the back that says "Max. Current: 15A" ?

Or was it because you didn't read the sticker on the back that says "Max. Current: 15A" ? :)

RWallmow
March 16th, 2012, 12:52 PM
Because you read the sticker on the back that says "Max. Current: 15A" ?

Or was it because you didn't read the sticker on the back that says "Max. Current: 15A" ? :)

I am betting option number two with how he worded that, but yeah, earlier I was going to chime in on them only being rated for 15amp, but I got side tracked.

Dms12444
March 19th, 2012, 12:19 PM
Well, although the IBM PC-JR was atypical for it's time, it draws 48 watts of power according to this one owner (http://www.youtube.com/watch?v=HxwP66skxjM&safety_mode=true&persist_safety_mode=1&safe=active) (I believe he was reading a specs sheet, on a sticker inside the machine).

Ole Juul
March 19th, 2012, 04:08 PM
Well, although the IBM PC-JR was atypical for it's time, it draws 48 watts of power according to this one owner (http://www.youtube.com/watch?v=HxwP66skxjM&safety_mode=true&persist_safety_mode=1&safe=active) (I believe he was reading a specs sheet, on a sticker inside the machine).
That is right in the ballpark for that kind of machine. However, it is microcomputer and not a minicomputer. :)

Tor
March 20th, 2012, 02:38 AM
That is right in the ballpark for that kind of machine. However, it is microcomputer and not a minicomputer. :)
Yep. One difference would be the PSU.. there's one from a minicomputer stored on a shelf here, it's not that physically big but the 5V rating is 200A.

-Tor

tingo
March 20th, 2012, 02:21 PM
Well, the specifications of the ND-Satellite/9 (http://sites.google.com/site/tingox/nd_900-135) I have says "circa 500W". And the ND-100/CX Compact (http://sites.google.com/site/tingox/nd_3392-1669) has a Phillips PE1049 power supply which is rated at 220 VAC, 5A or about 1100W.