Update Jan 11, 2022 – The build video has been released on YouTube and a new post on the build is available
It seems like a large percentage of the Commodore computers I get have no power supply with them, or even worse, one that will damage the machine. I made a Commodore 64 power supply earlier but now have another model coming without one, so I have decided that what’s needed is a bench power supply that will work with any Commodore machine that came with an external power brick. I also thought it would be nice to be able to simultaneously power an external disk drive like the 1541-II.
Power Requirements
I started by cataloging all the Commodore machines that have an external power brick… At least as many as I could think of but I keep finding more to add. From this, I could see that there a total of 5 voltages that are needed for a build that would cover all the models. They are (Listing the model that uses the most current):
- 5 Volts DC at 5 Amps for an extreme A500/A1200 config plus 1 external drive
- 9 Volts DC at 1 Amp for the Commodore 16 and 116 (if you want to support these)
- 12 Volts DC at 1.5 Amps for the A500 and an external drive
- -12 Volts DC at a measly 0.1 Amps for the Amiga’s
- 9 volts AC at 3 Amps for the early VIC-20s or 1 Amp if you don’t need early VICs
This results in 8 total pins (Updated to separate common and ground)
- Common
- 5V DC
- 9V DC (Optional for the C16 & C116)
- 12V DC
- -12V DC
- 9V AC phase 1
- 9V AC phase 2
- Ground
The project can be simplified (and cost reduced) quite a bit if you forgo support for the Early VIC-20s, C16, and C116. The C16 and C116 in particular just take a 9V DC, 1 Amp wall wart so incorporating it into the project would be trivial but pretty pointless. The early VIC-20 support requires a 9V AC, 3 Amp transformer, the only one I have been able to find costs about $20 so that adds significantly to the cost. Wall warts that provide 9V AC at 1 amp I find frequently at thrift stores, garage sales and even the local electronics supply store for $1 – $5 and are sufficient for the needs of the later Vic-20s, Commodore 64, Plus/4 and and Commodore 128.
The Power Chart
Additional Features
In addition to powering any machine I have on my bench I thought it would be nice if it could also provide information on the machines power usage. I found some compact DC voltage and current meters on Amazon that look like they will do the job (edit: 08-21-21 They will not work, they require that each voltage have an isolated common and, since the Commodores have a single common for all 3 voltages these meters will not work! See a brief explanation video here). I picked up a variety of them so I could see which ones I liked and have settled on a nice little unit that shows both voltage and current in a single display. It didn’t hurt that they only Cost about $10 for 3 of them.The options for AC meters were a great deal more limited. So limited in fact that I would recommend that you just forgo it altogether. The best meter I could find that could handle the low voltages required was large, expensive and limited to voltage only. It is also no longer available so, bleh!
Posts in this Series
Part 1 – This Post
Part 2 – Commodore Universal Bench Power Supply – Parts
Part 3 – Commodore Universal Bench Power Supply – Build
Part 4 – Commodore Universal Bench Power Supply – Making Cables
