Apple Power Requirments

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Apple Power Requirments

An interesting topic arouse in a different post. This leads to the question what are the power requirements of an Apple II computer? I thought this might make an interesting forum topic.

I do not know the accuracy of these numbers but they were published by Applied Engineering. All values are in milliamps and only apply to the +5V rail.

Apple IIe Only ------------ 1000
Apple II+ Only ----------- 1500
Typ 1 Meg RAM Card ------ 1100
HD Interface ----------- 700
Accelerator Card ------- 500
3.5 Disk Interface ----- 500
5.25 Disk Interface ---- 400
1 Meg RamWorks III ----- 400
Clock Card ------------- 200
CP/M Card -------------- 300 to 1000
Modem Card ------------- 400 to 900
Printer Interface ------ 300 to 600

If anyone has more exact figures, or figures for different devices, please post them.

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Re: Apple Power Requirments

That is nice and interesting data....

but it also raises a question:
why does AE claim for the RAMworks only 400mA ???

examining the datasheets for different 41256 chips ( that are the chips used in the RAM banks ) show
average at all companies that a single chip requires 70 to 80 mA per chip
so simple math ( if the card is completly populated with 1 MB that requires 8x4 chips = 32 chips )
32 x 70 mA = 2240 mA ( without the chips used for decoding and bufferin and without pull from buffering resistors )
32 x 80 mA = 2560 mA ( without the chips used for decoding and bufferin and without pull from buffering resistors )
what did they measure ? the empty card without RAM ) ???

another point is publication of the requirements of the drives ....
for the drives the bottleneck isn´t the 5 Volt branch.... it´s the 12 Volt branch !

normal Apple Powersupply only gives 1,2 to 1,5 Ampere in that branch....

Disk II pulls 450 to 600 mA while operating ( not spinning it drops to 350 to 400 mA )....
so while copy operation in partial time the pull runs up to 900mA

and a Harddisk ? it´s normal that a 3,5 " drive pulls about 500 to 700 mA....
and some cards also have remarkable pull at the 12Volt branch ... for example Eprom-progammingcards, and networking cards...

this short list shows that it´s important that both branches must be keopt under surveilance....

and another fact:
a switching powersupply operating at 85% gets close to maximum Temperature 50 degrees Celsius and more....
a switching powersupply operating at 65% only gets little more than 35 to 40 degrees Celsius....

and then it´s also important to know if the powersupply has temperature protection or not.....
if there is a protection it should switch off the supply if it gets more than 60 degrees Celsius
and if not ... well then the supply starts dieing hard but slow and after several weeks it just fails....

at least we learn one thing from the data....
it seems that some companies publish data in the same manor like automobile manufacturers publish data on
demand of fuel for 100 miles requested from their own models.....?

sincerely speedyG

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Re: Apple Power Requirments

Wasn't there a saying - "a little knowledge is dangerous"

If your numbers were correct then if you had a 1mb memory card then it would be pretty much the only card you could have in your Apple II. But the numbers aren't correct.

Those RAM specs are meant for professionals so they expect the reader to have some prior knowledge. They give you the maximum power draw but the RAM doesn't draw power steadily. Most of the power usage is during the refresh cycle. The refresh cycle is usually every 3-4 ms and the refresh only lasts a few ns.

That is nice and interesting data....

but it also raises a question:
why does AE claim for the RAMworks only 400mA ???

examining the datasheets for different 41256 chips ( that are the chips used in the RAM banks ) show
average at all companies that a single chip requires 70 to 80 mA per chip
so simple math ( if the card is completly populated with 1 MB that requires 8x4 chips = 32 chips )
32 x 70 mA = 2240 mA ( without the chips used for decoding and bufferin and without pull from buffering resistors )
32 x 80 mA = 2560 mA ( without the chips used for decoding and bufferin and without pull from buffering resistors )
what did they measure ? the empty card without RAM ) ???

[/b]
sincerely speedyG

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Re: Apple Power Requirments

Wasn't there a saying - "a little knowledge is dangerous"

If your numbers were correct then if you had a 1mb memory card then it would be pretty much the only card you could have in your Apple II. But the numbers aren't correct.

Those RAM specs are meant for professionals so they expect the reader to have some prior knowledge. They give you the maximum power draw but the RAM doesn't draw power steadily. Most of the power usage is during the refresh cycle. The refresh cycle is usually every 3-4 ms and the refresh only lasts a few ns.

Hello Wayne,
nice to smell your odor in the bark of the trees again.....

first of all - if argueing - the least would be, to tell "what you believe to be correct" ...
in other words why don´t you populate "correct" data in mA..... ( could it be that you even just don´t know correct values ???

lets just talk about facts - meaning datasheets ( and i can read them and much more - i even understand them..... )

first extract from 41256 datasheet ( HYB41256 from Siemens )
IMAGE(http://www.harrowalsh.de/download/Dataextract41256.jpg)

then lets just for example take a look to the 74LS245 ( Databus Latch )
IMAGE(http://www.harrowalsh.de/download/DataExreactLS245.jpg)

i´ll save you the pain to also show up some other datasheets from LS logic.....

but first of all... i hope you recognize the word "avarage"..... i hope you know about the deeper meaning of this word ? "avarage" is not the same meaning like "peak"...
and i hope it´s also known what the meaning of the word "standby" is....
at least to my knowladge "standby" means the chip does nothing ( meaning no read and no write just siting around )...

so lets get this things together from a stupid guy like me ( whom you claim to be "nonprofessional" .....-but sorry your wrong... i have a degree as electronic engineer for microprocessors from Technical University in Giessen-Friedberg ... such a pitty ! )

normal LS chips like 74LS04 or similar draw current of about some 20mA to 35 mA ( in case of doubt, i can also come up with that datasheets too....)

the 41256 draws in "standby mode" 2mA....
that´s only valid under the condition that the chip does no read and no write and that there are no pullup or pulldown resistors or latches behind the chip that draw current.... nearly no circuit is used in that way.....

the LS245 - if it has pullup resistors draws less current in standby mode 48 mA...
the LS245 - if it has pulldown resistors draws at least 60 mA ......
this is just recalled to explain that there is difference of drawing current when outputs are pulled down....

even if you would asume the 41256 to draw only 50mA while working ( and that´s more than optimistic ! )
then the 32 chips would pull at least 1600 mA = 1,6 Ampere !without the other logic chips on board....
- but if you take a closer view to the empty board with only logic chips - well the 400 mA sounds realistic....
( i hope i may subsume that you agree that to be far more than 400 mA listed above ??? )

and thats´s just if you ignore that little word "avarage" .....

just back ro your recall of epigrams ... some turn back around.....

last but not least... what´s the target of this thread listing ????
it´s collecting "worst case" scenario´s, to guess the power that might be drawn from powersupply ....
in best guess listing you might have a full loaded Apple IIe ( but without accelerator or full loaded 1 MB RAMcard and the system "maybe" keeping stable ( if you are lucky )

next time i´d at least expect you to list facts instead of just leaving your odor on the bark of the tree...
sincerely speedyG

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Re: Apple Power Requirments

My apologies if I gave offence with my previous reply. I wrote that during my morning coffee break and was a bit rushed

I work for a living and have a life so I’ll look up some specs and write a small essay on the weekend when I have more time.

But you shouldn’t need that to see that the math still doesn’t work. Your original number was the total +5 volt output of the power supply with nothing left to run the IIe with. You’ve come down but you’re still way too high.

Look at a IIe power supply. The North American ones gives a +5 output of 2.5 amps.
With a IIe using 1 amp and if a RamWorks did use 1.6 amps then you’d already be over amperage on the power supply. You be lucky to have power left to run even a floppy drive? What if someone also bought the 512k or 2mb expander. With your figures they wouldn’t have had enough power to even turn on their IIe even with all the regular slots empty. Lots of people also had a Transwarp and occasionally a 1mb slinky card and more.

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Re: Apple Power Requirments


Look at a IIe power supply. The North American ones gives a +5 output of 2.5 amps.

Hello Wayne,

2,5 Ampere ??? Sure -i must state that i don´t have the U.S. version on the shelf... - but at least the European version delivers at the +5 Volt 4 Ampere to 5 Ampere.... depending to it´s version.... - and in fact they are not that far different from the U.S. Version except in the primary voltage area ( where the U.S. version works with 110 Volts and the European one works with 220 V/ 230 Volt ) where the population of the powertransistors and the frequency determiniing parts differ from each other upmost the transforming switching coil ....
and the heavy duty version from AE claims to serve with 7,5 Ampere at the +5 Volt branch and with 2 Ampere in the +12 Volt branch !

In fact i don´t believe anyone ever has connected a amperemeter between powersupply and Computer to measure the drawn values instead of calculating them....

- but 400 mA stated from AE is also not believable and rather more to be a mythical value and rather more fits for given value of an unpopulated card or probably one only populated with 1 bank (i.e. 256 kb )like the values given from manufacturers of cars about the use of gasoline per 100 miles in their models ( only able to be reproduced within a cabin on rolls without airresistance and alltime plain ground..... )
- but nobody uses a car inside a cabin....

even if i´d subsume a card with 256 kB ( as most of them have been sold ) a card completely populated with 1 MB would end up at a average value about close to 1,6 to 1,8 Ampere....

In fact it could turnout to become a summer project for someone ( who has a lot of those cards on the shelf ) to make real measurements with real values instead of calculations on datasheets.... the results might be quite suprizing ....
sincerely speedyG

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Re: Apple Power Requirments

And to really confuse the situation...

Both my Apple II silver supplies are labeled as 1 amp. The one I repaired for my Rev 4, where I had the confusion about what fuse to use had a sticker I peeled off that covered the specs but it's 1 amp and the silver supply for my Rev 0 that I just changed the switch in has 1 amp printed on back and since I had it open to change the switch I grabbed my "cheater" glasses so I can make it out, but it also has a 1 amp fuse. Slow blow 1 amp.

So I'm guessing that the 2.5 amps Apple lists may be at startup. I bet that the use of a slow blow fuse is for that. When I was researching for the repair of my supplies and I could only find the Aztek supply schematics it listed the fuse and a 2.5 amp fast blow. So I guess they got a better handle on the startup power usage and went with a fast blow for safety.

One more interesting note. I have the newer Apple II Rev 4 silver supply and the older Rev 0 Apple II silver supply, the older one has a case size the same as the Aztek and the other is about an inch to two inches longer. I need to take some pics. Also the newer supply actually has a ground wire from the power entry module to the chassis and the older doesnt. It relies on the screw touching the metal inside of the case and the metal in the entry module that provides the strength for the plastic covered module.

Anyway I though it was interesting.

Cheers,
Corey

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Re: Apple Power Requirments

Hello Corey,
your talking about the primary voltage area ( i.e. input ) and there the values differ from facts like European ( or switchable ) version and US version ( i.e. 110 Volt / 220 Volt )....
and then there are other factors related to the kind of transmission that part of the power put into the supply gets lost ...
so just to set up : the 1 Ampere fuse indicates that some 750mA to 800 mA is put into the front of the powersupply ( so that would indicate about 80 Watt input = input voltage 110 Volt x input current in Ampere 0,75 Ampere ) then reduce the output by transmission losses of say 35% ( avarage value ) and you get output of about 52 Watt to 58 Watt ----

but that OUTPUT calculates as: 5 Volt x 5 Ampere = 25 Watt and 12 Volt x 1,5 Ampere = 18 Watt and each -5 and - 12Volt both each x 0,25 Ampere 1,25 Watt and 3 Watt - so together the negativ branches add up to 4,25 Watt.....and total of the Output adds up to 25 Watt + 18 Watt + 4,25 Watt = 47,25 Watt...

the Rest of the difference to 80 Watt input 32,75 Watt is lost in transmission...

comparing that "normal" powersupply ( listed above ) with the "heavy duty" version from AE ( below ) :
+ 5 Volts x 7,5 Ampere = 37,5 Watt
+ 12 Volts x 2,0 Ampere = 24 Watt
- 5 Volts x 0,5 Ampere = 2,5 Watt
- 12 Volts x 0,5 Ampere = 6 Watt
all together adds up to 70 Watt output ( and if you add the loss of average 35 % => 94,5 Watt )

so the "heavy duty" supply from AE has 33% more power than the "normal" one...

and just another info to that topic... : in the early ´80s a thirdparty company called TIGER Inc. from taiwan made a powersupply close to the one from AE with only 2 differences: the 12 Volt branch had 2,5 Ampere and they had the wrong plug ( pins in row instead of block ) .... i bought in those days 4 of those supplies and kicked out all original supplies from my Apples and replaced them ( changing the plugs by desoldering and soldering cables.. )
and they did their job the entire time since then without any trouble ( and another difference : the TIGER Inc. supplies were also sold for european voltages and better airvented )- and good news for the european Apple users...: there is a guy, who regular sells that supplies ( still factory sealed new ! ) in regular auctions at ebay nearly every 2 or 3 weeks one supply... ( i guess he has a complete storage box of them.... )

sincerly speedyG

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Re: Apple Power Requirments

Wow your bringing back bad memories of universty. The non drunken parts!!!!

LOL

Cheers,
Corey

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Re: Apple Power Requirments

Then I guess Apple saying that their slinky card with 256k uses 100mA and with 1mb uses 200mA would be even more impossible

- but 400 mA stated from AE is also not believable and rather more to be a mythical value and rather more fits for given value of an unpopulated card or probably one only populated with 1 bank (i.e. 256 kb )like the values given from manufacturers of cars about the use of gasoline per 100 miles in their models ( only able to be reproduced within a cabin on rolls without airresistance and alltime plain ground..... )

sincerely speedyG

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