DIY European Apple-1 replica powersupply

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speedyG's picture
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Joined: Nov 16 2011
Posts: 2413

Hello AF-members,

in the meantime after few years there is a large group of users from Europe that have a Apple-1 replica,
or are at the moment in construction of such a device.
Because the original Stancor transformators are dependent to 115 Volt power from the wall outlet -
there is at the one hand option to use the original transformers and a stepdown transformer from 220 Volt
to 115 Volt - or at the other hand to build immediatly a supply for 220 Volt without the Stancor
transformators.

I've made a solution with transformators that offer both options but are setup for 220 Volt
and made some pictures and a schematic of that supply. The page is availiable at:
http://www.appleii-box.de/A33_Powerbrick.htm

here short overview:

sincerely
speedyG

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In early days I had a lot of money but no time - now I have no money but a lot of time....
the second part includes less friends but a lot more joy on life....

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Offline
Joined: Oct 9 2011
Posts: 1063
Re: DIY European Apple-1 replica powersupply

This has me confused.

You need to be at least 2v above the regulators for them to work. I recently posted about needing more than that even with some regulators.

How does this with reliably with 6v and 12v? It should need minimally 7.5 and 14.5V

speedyG's picture
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Joined: Nov 16 2011
Posts: 2413
Re: DIY European Apple-1 replica powersupply

Hello Corey986,

that's one of the problems while reading without doing the math....
At the Apple-1 the AC voltages pass full wave rectifiying bridges ( of 4 Diodes )....
and specs of transformators usually list the "avarage value" of the voltage and not
peak to peak voltage....
This results to following math:
6 Volt x 1,41 ( avarage factor or i.e. sometimes also called "effective voltage" ) = 8,46 Volt AC peak to peak
12 Volt x 1,41 ( avarage factor or i.e. sometimes also called "effective voltage" ) = 16,92 Volt AC peak to peak

and not to forget that at normal conditions the mainboard does not use the entire current -
resulting to the fact that the big electrolytic caps at the mainboard also slowly get loaded up higher....
at the other hand ( and that's a thing most don't think about ):
the heatdisaption at the mainboard is rather poor because except of the 5 Volt regulator the other
regulator IC's don't even have a cooling sink....
and the higher the voltage and the longer the computer is turned on - the more the heating of the IC's
give a problem....

This powerbricks helped a lot keeping the heating reduced as far as possible while i tested them
in so called "burn in test" - running the mainboard 24 hours without power off.....

- but even though resulting from the "long term testing" i added to the 3 TO-220 IC's cooling sinks with thermal paste....:
https://www.conrad.de/de/kuehlkoerper-18-kw-l-x-b-x-h-254-x-25-x-85-mm-to-220-marke-assmann-wsw-v8510b-183971.html

I guess that eliminates the irritation....

sincerely
speedyG

__________________

In early days I had a lot of money but no time - now I have no money but a lot of time....
the second part includes less friends but a lot more joy on life....

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Joined: Oct 9 2011
Posts: 1063
Re: DIY European Apple-1 replica powersupply

Your right I didn't do the math. I read your posting while standing in a long queue at Costco.

Cheers,
Corey