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| | Previous Messages | Posted By
MikeZ
on 2010-08-23
12:36:38
 |  Re: Voltage conversion from UK to US
Siz:
Thanks for refreshing my memory. Yes, the C64's 6526 CIA is what I was thinking about.
Its TOD clock depends on an external 60/50 Hz source.
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Posted By
siz
on 2010-08-23
10:28:29
| Re: Voltage conversion from UK to US
If my memory serves well the CIA in the C64 uses the voltage frequency (50Hz/60Hz) to step the time-of-day counter.
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Posted By
MikeZ
on 2010-08-22
09:46:11
| Re: Voltage conversion from UK to US
gerliczer,
Yes, of course you are correct about generation of the system clock signal.
I was concerned about exactly how "jiffies" are created. The Kernal updates the jiffy clock during each raster interrupt at raster line $CC. That is a definition of a juffy. But, that only works when interrupts are enabled. The NTSC freq of 894khz divides exactly into a factor of 60 and the PAL freq of 884Khz divides exactly into a factor of 50. So, it is easy to see that a jiffy could be derived from the basic oscillator frequencies. Yet, the "jiffy" clock depends on raster interrupts instead of a strict hardware timer countdown to create a jiffy. I suppose that if you derived the time it takes for one raster vertical count cycle (From $CC to the next$CC) you would also come up with the value of 1/60th or 1/50th of a second??
Any thoughts??
Anyway, I thought I had read somewhere that the concept of a "jiffy" was tied to the powerline freq and I stand corrected with regard to the issue here.
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Posted By
Chicken
on 2010-08-21
17:48:21
 | Re: Voltage conversion from UK to US
Only the drives with internal PSUs (e.g. 1541, 1551 and 1571) could be harder to get running. Even though Sixteen Plus didn't list any of these, I searched the forum for answers.
I compiled a few facts on this topic from older threads. For your convenience I just quoted the relevant stuff. Some of it applies to all machines anyway.
http://plus4world.powweb.com/forum/4621
JamesC
"I have tried this on both a 1541's 110v power transformer as well as 1551's transformer on a 110 to 220v step-up transformer.
Both the 1541 and 1551 have 16khz crystals, otherwise I would suspect 50/60hz differences. Two other people in the States that also have 1551s have simply changed the transformer without changing the crystal, and theirs work fine."
http://plus4world.powweb.com/forum/2404
JamesC
"On YOUR 1551 do you have to do anything for the 50Hz - 60Hz change, or does it work fine on 60Hz?"
BushRat
"Had no problem. Remember that those bigger 50hz xformer core were happy and ran cool on 60hz. The 60hz cores will run hot on 50hz.
The 1551 that I use is in a US 1541 case and 60hz supply... never had a glitch."
http://plus4world.powweb.com/forum/5140
Crown
"Speed of these machines are not dependant on the frequency of the power supply, first of all the power is converted from AC to DC and in DC land you see nothing from the frequency of the AC signal.
Speed is decided by the clock crystal, and drives released in the States and in Europe has the same crystal, that's why you don't need any modification."
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Posted By
gerliczer
on 2010-08-20
16:23:16
| Re: Voltage conversion from UK to US
MikeZ,
No computer uses the powerline frequency to derive its clock signals from. It generates them on its own. The NTSC and PAL versions of 264 series computers differ only in the quartz oscillator giving the base frequency and the KERNAL ROM that selects NTSC mode when initializing the system. Well, actually the RF modulator may also be different, but that does not count here. So as Chicken said it's the easiest, probably cheaper and the most convenient to buy local power supplies.
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Posted By
MikeZ
on 2010-08-20
10:56:10
| Re: Voltage conversion from UK to US
The computer uses the power line frequency to determine internal hardware timing and jiffies. If your current system will be used in the US, then it might be wise to investigate a static inverter that produces 50 hz AC from 12VDC. Th the US, these kinds of things are commonly used in an automobile. They plug into the cigarette lighter and produce few amps at 110VAC and 60 hz. Surely there is a Euro version that produces 220VAC and 50HZ. This can be stepped down with a transformer to 110VAC. Many of us use the power supply from an old PC with all the 12V taps tied together for more amps, instead of an actual automobile battery.
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Posted By
retroscener
on 2010-08-12
23:31:41
 | Re: Voltage conversion from UK to US
Thanks. Yes, all my systems are PAL. Phew. I was banking on that I wouldn't need to change any chips 
I'll check the links out properly in more detail when I'm home next week as I'm away at the moment. I'm pretty sure my plussy has the square socket. I can't remember the voltages to check right now. I'm more interested in bringing my expanded C16 with me if I make the big move but preferably both.
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Posted By
Chicken
on 2010-08-12
21:40:16
| Re: Voltage conversion from UK to US
You need a "Step up Voltage Converter".
Just a plug adaptor works only if you can change the PSU to handle 110V (many laptop PSUs can handle 110-240V nowadays and some stuff like electric razors can be switched to 110V)
Those voltage converters are widely available, e.g. here:
http://www.tlc-direct.co.uk/Main_Index/Transformer_Index/UK_to_USA_Converter/
They also have a calculator tool (however, that's just for the other way around... USA equipment in UK). Nevertheless, there are some interesting hints:
http://www.tlc-direct.co.uk/Technical/DataSheets/PatrickBros/ApplianceCalculator.html
It's probably better to buy them in the States once you are there. Radio Shack etc usually have them.
It might be even cheaper to buy a USA PSU for the 1541-II on Ebay. Same for all other external PSUs. Does your plus/4 have a round or a square socket? A standard C64 PSU can be used if it has a round socket.
If you are running a PAL system, you don't need to change any chips.
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Posted By
retroscener
on 2010-08-12
20:33:16
| Voltage conversion from UK to US
Thought I'd ask around on both the main 264 series sites. There is a strong possibility that I might be moving to the states in the near future.
What I need to know is that I plan to take my expanded C16, my Plus4, my C64, and my 1541mk2 drive with me. Most games are PAL only so don't want to switch to NTSC. I'm pretty sure I can get hold of an american PAL TV in the states easily enough to run them on.
But as the voltages are different, is there an easy way to convert the UK equipment to run in the USA? Would a UK-to-US plug adaptor suffice? I'm thinking not.
Would I need new power supplies?
Would I need to change any chips inside the machines? I hope it's not too complicated.
If there is a simple solution for long-term use, such as a voltage adaptor I'd really appreciate it. Any links that can help me are very welcome.
How simple (or difficult) can it be?
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