Re: C64 power supply replacement

From: Ryan Underwood (
Date: 2004-01-21 05:08:17

On Sun, Jan 18, 2004 at 10:50:31PM +0200, wrote:
> > 
> > Because I need parts I can easily get (read: at Radio Shack...) ;)
> I believe you will easily find a 120 to 9 V xformer. Or just use the one
> from the original C64 PSU.

I would, but it is full of plastic.  I'm afraid I would break it just by
trying to chisel it out of there! :)

> > > > - Use voltage divider to derive 9VAC from secondary and send that
> > > Do you mean, a two-resistor voltage divider? I hope not.
> > 
> > Yeah, such as:
> >
> You can't use such a voltage divider for power applications, for 2 reasons:
> the utilization factor is abysmal, you would end up dissipating more (perhaps 
> much more) power on the resistors in the divider, than the power 
> consumed by the computer. Voltage dividers are used for signal reduction, 
> such as the loudness regulation in amplifiers. The second, practically
> unsormountable disadvantage of such circuit, is that Z1 and Z2 (R1 and R2
> in case of purely resistive impedances, which is what you'll have in practice)
> will have to vary as the current consumption varies! If you actually check
> the very nice web page you mentioned, you will see that by varying ZL, Z1
> and Z2 will have to vary, too. Otherwise Vout will not be constant.

Thanks for the explanations, that was highly educational.

Ryan Underwood, <>

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