figueroa@oodis01.ARPA (Andrew Figueroa) (01/25/89)
All the references to "beefier power supplys" make me ask about my own recent project. I built a C-64 P/S from a "Power-One" HB5-3/OVP-A 3 amp DC power supply (this is regulated with overvoltage protection). I wanted to get 9 VAC off of the transformer secondary leads but I could not get that to work. I needed a 9V 1 Amp transformer to complete the project but only found a 9V .5 Amp transformer to complete the kit. My review of the C-64 schematics and references in the C-64 Programmers Reference Guide led me to believe that .5 Amp is enough. I rounded the "kit" out with a 1 Amp fuse on the inbound 120 VAC and topped it off with a 230V 5" muffin fan (the 230V fan runs slowly enough to be totally quiet yet provide for very COOL operation. I've run this outfit for many hours without any problems. Any ideas that I may get into power insufficiency trouble with this homemade effort? Think it will drive an REU without going up in smoke? (disclaimer - "Kids, don't try this at home. You may burn yourself with the soldering iron, burn the house down, or destroy your computer, yourself, or a friend." I don't know how these things work - I just put them together!) Andy Figueroa aka "figueroa@wpdis01.arpa"
fred@cbmvax.UUCP (Fred Bowen) (01/26/89)
In article <145@oodis01.ARPA> figueroa@oodis01.ARPA (Andrew Figueroa) writes: >I built a C-64 P/S from a "Power-One" HB5-3/OVP-A 3 amp DC power supply (this >is regulated with overvoltage protection). [...] >I needed a 9V 1 Amp transformer to complete the project but only found a 9V .5 >Amp transformer to complete the kit. My review of the C-64 schematics and >references in the C-64 Programmers Reference Guide led me to believe that .5 >Amp is enough. The "beefier" supply that comes with the 1764 expander is 4.3A@5V and 1A@9V, designed around the assumption something is sucking power from user, cassette, and expansion ports. For example, the 1750 peaks out at around 500mA, and a BusCard plus 80 column adaptor will certainly draw over 500mA. A 1670 modem takes about 50mA, and a datasette requires 5V 150mA as well as 9V 500mA. An analysis of 5V requirements depends upon the vintage C64 you have, but even the more recent short boards (say 1.5A max) plus a RAM expander (.5A) combine for a 3A minimum recommendation. An analysis of 9V requirements shows SID (50mA) plus datasette (500mA), hence the 1A recommendation. >(disclaimer - "Kids, don't try this at home. You may burn yourself with the >soldering iron, burn the house down, or destroy your computer, yourself, or a >friend." I don't know how these things work - I just put them together!) Good advice. >Andy Figueroa >aka "figueroa@wpdis01.arpa" -- -- Fred Bowen uucp: {uunet|rutgers|pyramid}!cbmvax!fred arpa: cbmvax!fred@uunet.uu.net tele: 215 431-9100 Commodore Electronics, Ltd., 1200 Wilson Drive, West Chester, PA, 19380
jgreco@csd4.milw.wisc.edu (Joe Greco) (01/26/89)
In comp.sys.cbm article <145@oodis01.ARPA>, figueroa@oodis01.ARPA (Andrew Figueroa) wrote: >I built a C-64 P/S from a "Power-One" HB5-3/OVP-A 3 amp DC power supply (this >is regulated with overvoltage protection). I wanted to get 9 VAC off of the >transformer secondary leads but I could not get that to work. {munch... chomp... burp} >Any ideas that I may get into power insufficiency trouble with this homemade >effort? Think it will drive an REU without going up in smoke? 3 amps? Should be no problem. The original supply was rated at either 1.5a or 1.7a at 5vdc, and the 64 very nearly drew that much. I used a 2.5a Apple supply for quite some time with great success (with a 1750 and quite a BIT of other junk). Now I use a very nice big heavy 5vdc supply that could power most of lower Florida (and certainly the 3 or 4 64's I have on it) :-) -- jgreco@csd4.milw.wisc.edu Joe Greco at FidoNet 1:154/200 USnail: 9905 W Montana Ave PunterNet Node 30 or 31 West Allis, WI 53227-3329 "These aren't anybody's opinions." Voice: 414/321-6184 Data: 414/321-9287 (Happy Hacker's BBS)