Powering a C64 (or VIC-20) with a USB Power Bank

[Rich]

Youtuber Jan Beta has made a video about Powering a C64 with a USB Power Bank and showing a VIC-20 aswell, worth a look.

https://www.youtube.com/watch?v=U5nrWfLmqR0&t=1s

[nefaurora]

Yes, A great video! ...and totally do-able!

I am shocked that no-one has "cashed-in" and already making these USB C64 or USB VIC-20 Power supply cables and selling them on ebay or etsy yet as they are literally a joke to make!

Tony K.
Commodore Collector/Restorer
Melbourne, FL.

[Mike]

[...]

[...] totally do-able! [...] I am shocked that no-one has "cashed-in" [...]

Doing like suggested in that YT video is maybe good for a hackish quick check to see that the base unit sort of works, but it is unsuitable for daily use:

• The long board C64 does not work at all (the 12 VDC for VIC-II cannot be generated from the 5 VDC),
• in case of the short board C64, the SID needs to be removed. Sound only works with one of the SID replacements that do not require either 9 VDC or 12 VDC.
• Also with the C64, the CIA TOD clocks will not work (they are 'clocked' with the 9 VAC).
• In case of the VIC-20, it 'works' for the CR mainboard revision, but (also for C64):
• the tape port will not function (the tape motor gets its supply from the 9 VAC), and
• anything connected to the user port that relies on the 9 VAC will not work either (RS 232 level shifters, EPROM programmers, ...)

Just a few "buts" too many ...

[nefaurora]

Yeah, I knew about the no power at the userport.... Still friggin cool though...even to just play around with especially for a VIC-20...C64, ehh, maybe not so much...

)

Tony K.

Tony Kovar
Commodore Collector/Restorer
Melbourne, Florida

[JonBrawn]

There's also a potential problem if you start plugging in cartridges - I'd guess that some might pull the 5V line down a bit, which might cause stability issues. I can't imagine this is going to work well with a VIC-20 that has the two-prong AC power connector and the built-in voltage regulator/room heater.

[Mike]

I can't imagine this is going to work well with a VIC-20 that has the two-prong AC power connector [...]

The aforementioned YT video explicitly excludes the 2-prong variant of the VIC-20 from the workable options, and yes - the voltage regulator on the 2-prong mainboard would be operated far below its normal requirements. In effect its output voltage should be below 4.3 V with an input voltage of only 5.0 V, rendering the whole setup non-operational.

But then again, even with the CR mainboard, supplying the VIC-20 with 5 V only is just tinkering around and nothing usable for regular operation.

[JonBrawn]

Something's not firing on all cylinders - Denial has just emailed me to notify me that Mike made that post!

[Mike]

@JonBrawn: PM sent

[jjne]

I'm thinking the solution for this would be to create a 9VAC signal from the 5V input. This is certainly possible but the way of producing such a thing that works reliably isn't immediately obvious to me. I do intend to look into it though. How would these machines respond to a square or triangle wave at 50Hz?