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From: dbell@cup.portal.com (David J Bell)
Newsgroups: sci.electronics
Subject: Re: 12v dc -> 9v ac converter
Message-ID: <39250@cup.portal.com>
Date: 14 Feb 91 04:09:09 GMT
References: <91043.135514UD186413@NDSUVM1.BITNET>
Distribution: na
Organization: The Portal System (TM)
Lines: 22

>I'm interested in building a converter that would allow me to run a
>Commodore VIC 20 computer from a 12v motorcycle battery.  The
>computer needs a 9v ac input.  Is it possible to synthisize this
>easily?  The current load is less then 3 amps max.  The setup will
>be used in a robot.  Anyone have any ideas?

>John Nordlie               University of North Dakota
>                           Space Studies Dept.

Probably very simple... The transformer originally used supplied 
feeds a rectifier and filter in the VIC-20. The drop across the
diodes will probably drop the 12V DC to pretty close to the peak
rectified voltage. The only possible problem I would anticipate
is the chance that Commodore used the AC input to derive a negative
supply. If this is the case, you would then have to open the case,
determine the supplies required, and build a set of regulators to
"split" the 12V into +/- 5 or whatever is required...

Basically, you need to learn a little more about the VIC-20's
power supply. Maybe some VIC hacker will post here?

Dave


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