Re: Converting a Commodore 64 from NTSC to PAL

From: Gerrit Heitsch <>
Date: Sat, 14 Apr 2012 18:18:49 +0200
Message-ID: <>
On 04/13/2012 10:57 PM, Pasi 'Albert' Ojala wrote:
> On 04/13/12 20:59, Gerrit Heitsch wrote:
>> So unless the circuit that converts the 9V AC into a 50 Hz TTL-signal
>> contains some kind of filter, the TOD clocks cannot be accurate.
> Hi,
> There is nothing impossible about using a filter at the TOD input pin,
> and it can have input hysteresis to guard for noise.

When I built my own 50Hz circuit for an Amiga 2000 power supply years 
ago I just ran a few gates of a 74LS14 in series after the opto coupler 
and then used a 10nF cap between one of their output/input connections 
and ground. Not recommended to do it this way, but it worked flawlessly 
for years and improved the accuracy greatly.


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Received on 2012-04-14 17:00:22

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