View Full Version : c64 powersupply build question. 9vac rail unregulated?

September 26th, 2016, 10:38 AM
I recently got some adapters to make a c64 psu but my 9vac wall wart is unregulated but for the correct current (1 amp). Will this work or does the c64 draw more current then that? if it does this may cause a voltage spike which is my concern. if this is how the original supply functioned as well then this won't be a problem but I would like to know before I find out the hard way.

September 26th, 2016, 11:50 AM
I use a portable hard drive power supply for the 5 VDC, and an Atari power supply for An Atari 800 for the 9 VAC. The Atari supply puts out unregulated 10VAC. I used this setup to repair and operate my three C64s. I used one of those unit extensively for about a year with no issues what so ever. The Atari supply drops to about 9VAC under load. The Atari supply is just a 120 VAC to 10 VAC transformer. No electronics in the Atari supply at all.

The power supply for later Ataris, like the 600/800XL and 65/130XE are AC to DC and can't be used for this purpose. Any transformer that puts out 9 to 11 VAC would work fine, I just happened to have some Atari stuff laying around. I'm not sure the AC supply you have is up to the task however. The Atari supply is good for about 3 amps I think. I'm not sure 1 amp is sufficient.

September 26th, 2016, 12:11 PM
Regulation only applies to DC power supplies. With AC, the "regulation" is inherent to the ratio of the transformer windings.