Re: C64 power supply replacement

From: Mike Paull (
Date: 2004-01-15 09:46:30

Has anyone else come up with a design we can build that lets us use a PC
power supply to power the C64? Personally I prefer this option because we
can power our disk drives too. And as for noisey fans, don't be tight with
the $$$ and buy a decent PSU and you won't have a noisey fan.

As for bulk, well i'd rather have ONE PC power supply instead of six or
seven brick power supplies.


On Sun, 11 Jan 2004 13:11:10 +0200, you wrote:

>I must object to that design. Not only is it more complex and expensive than the one I presented earlier, it also has an excellent chance of frying your C-64! Let's analize the circuit for a moment, shall we? The schematic is
>- it contains 2 integrated circuits and 6 (!!) bipolar transistors.
>- if ANY of the active components mentioned above barfs, you end up with a constantly positive or constantly negative +12 or -12 V DC instead of 9 V AC - and since you depend on the functioning of 8 active elements in switching mode, your chances are very good (or bad, depending on your point of view).
>Other disadvantages include:
>- Requires more conponents AND it still requires the PC power supply. It will be bulky AND it will be noisy (fans in the PC PSU)!
>- Produces a SQUARE wave instead of a sine, for the 9 V AC. I don't know about you, but I won't be powering my C-64 with a square wave, even if it survives the first few days.
>- The frequency of the wave is not steady, as it is produced with a simple RC element. Sure, it might work at the beginning, when you construct the device, but wait till it's a warmer day, or a colder day, or heck, if the humidity is much higher or lower....
>- The BD135/BD136 transistors are subject to considerable stress. They will definitely produce heat and will be a good candidates for crapping out one nice day.
>In comparison, the design I presented is much simpler, it will never fry your C-64 (it uses the 7805, which has protective circuitry to protect itself and the target, and it's virtually impossible to damage), it has only 1 active component (the 7805), it's silent (no fans), it "produces" a 9V sine wave, as the original PSU and at the correct frequency. The only active element to warm up is the 7805, which, as I already said, contains protective circuitry that saves it from overheating as well. The only disadvantage of my design would be that youneed a 220/9V transformer, but I suspect you could use the one from the original C-64 PSU.
>> -----Original Message-----
>> From:
>> []On Behalf Of ext Luca 
>> Di Pasquale
>> Sent: 11 January, 2004 12:03
>> To:
>> Subject: Re: C64 power supply replacement
>> Just change a resistor and a capacitor (R1 and C1 in that 
>> project) and you
>> will magically get the 60 hz needed on NTSC C64's (and 
>> finally get rid of the
>> shitty C64 power supply!) :-)
>> Ciao,
>> Luca
>> > Remember that that is 50hz so in the non-PAL C64 your 
>> clocks will be 
>> > wrong including the CIA timers which get their frequency from the 
>> > 9VAC.
>> > 
>> > --Ray
>> > 
>> > >For anyone looking at replacing a C64 power supply with 
>> one from a PC
>> > have
>> > >a look at this web page;
>> > >
>> > >
>> > >
>> > >This is the IDE64 home page however they have a nice 
>> little DC to AC
>> > >circuit so you can power your C64 from the one power 
>> source instead of
>> > >having one for ac and one for dc.
>> > >
>> > >I haven't built it yet so I can't say anything about it's 
>> reliability or
>> > >design.
>> > >
>> > >Mike
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