Re: 9VAC from 5VDC?

From: Gerrit Heitsch <>
Date: Mon, 16 Sep 2013 16:53:34 +0200
Message-ID: <>
On 09/16/2013 03:18 AM, Jim Brain wrote:
> On 9/15/2013 5:11 PM, Bil Herd wrote:
>> I posted an example of how to do a 5VDC/9VAC convertor using the first
>> transformer I found on Digikey that matched thebasic specs , there are
>> probably all kinds that would work. The design is two single-ended to
>> ground drivers which I show as TIP120 just for current and gain without
>> worring about the parameters.  Transformer can be a Single Primary
>> 110V to
>> 48 VAC Centertap secondary or I showed a dual primary with the 110V
>> primaries wired in series and 24 VAC Centertap.   I have not tested the
>> design or done the real exact 2nd level of math, this is an example of
>> how
>> I have done this in the past.
> My main question on that transformer is the specs show it as 500mA
> Current output (Max).  Since the C64 might need 1A @ 9VAC, is that a
> concern?

It depends on the C64... The last board (250469, with the large PLA) 
uses less than 200mA on 9V AC. The older boards need about 600mA on 9V 
AC. This means just the computer, nothing else (like something attached 
to the user port for example).


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Received on 2013-09-16 15:00:08

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