Re: Power consumption of Apple II with Monitor?

[Michael J. Mahon <mjmahon@aol.com>]

Charlie <charlieDOTd@verEYEzon.net> wrote:
> On 4/13/2011 10:30 PM, rich12345 wrote:
>> On Apr 13, 6:20 pm, Charlie<charlieD...@verEYEzon.net>  wrote:
>>> Sure.  Without the monitor:
>>> 
>>> 34 watts on power-up
>>> 29 watts after a second or two while the drive boots
>>> 24 watts with no drive running
>>> 
>> 
>> but Michael J. Mahon wrote earlier:
>> 
>>> When I constructed my AppleCrate II, I measured the average power
>>> consumption of an Apple //e main board (no cards) at about 4.2 Watts.
>> 
>> you're measuring 20 more watts that Michaels setup with no cards.
>> 
>> 24 - 7 (for system saver)
>> 
>> 17 watts...  You mention that you have duodisk and serial card.  Do
>> these two cards take this much power?
>> 
> 
> Maybe Michael J. Mahon was measuring the power consumed by the board at
> the output of the power supply.  I'm measuring is at the line side.  The
> power supply efficiency could be low.  If we say 50% (just a guess) then
> 17 watts / 2 = 8.5 watts.  Still higher than Michael gets but did he have
> a keyboard attached?  I also failed to mention I have a standard 64K card
> in the AUX slot which I consider normal.  I don't know if Michael had a
> card in the AUX slot.  He said (no cards).
>

You are correct--I measured the DC power consumption of the +5v supply. The
+12v drain is about 2 watts (it's actually used to take some load off the
+5v supply, for some reason--maybe just to load it enough to keep it in
regulation). 

The Aux slot RAM card (which I did not include) is potentially a 2-3W
drain, so maybe that's a significant factor. 

Still, I'd be surprised that the switching power supply is less than 50%
efficient. 

That would certainly make a case for battery powering an Apple II directly
rather than using an inverter and  "plugging it in"!

-michael  -  NadaNet 3.1:  http://home.comcast.net/~mjmahon