Allows up to four 4-pin DIN Commodore Floppy Disk Drives to use a single Power Supply
I created this PCB to eliminate the growing pile of power supplies needed to power my stack of Commodore Floppy Disk Drives. Freeing up three AC power outlets is also a bonus!
I have not specified any particular enclosure as what suits me may not be ideal in your situation. I'm happy to work with and use metal enclosures but some prefer plastic.
For the optional Power LED header, resistors and LEDs/cabling, any convenient parts can be used so I've not specified exact part numbers. The PCB pads suit 0805 (2012 metric) SMD resistors.
R1 300R 0805 (2012 metric)
R2 1K 0805 (2012 metric)
3 Way 2.54mm header
I like using the metal cased DIN plugs but feel free to use whatever you can source. The Switchcraft DIN plugs are quite expensive compared to those with plastic covers.
RS have their own branded metal cased DIN plugs that both look quite good and are cheaper than the Switchcraft DIN plugs.
To connect to a 1541-II or 1581 you need to make 1 to 1 cables with three core cable. I used three core 0.75mm cable that is commonly used for AC Mains appliances here in Australia.
Pin 1 - 5V
Pin 2 - GND
Pin 3 - N/C
Pin 4 - 12V
The pins in a DIN plug aren't really suited to use cables with larger conductors. As there is a bit more room in the 4 Pin DIN plugs, I soldered to the side of the pins rather than try to put the conductors inside the pins.
My Excelerator+Plus drive has a 5-Pin DIN socket for power input so I made one cable with a 4-Pin DIN on one end and a 5-Pin DIN on the other. This plug has been marked to make sure it doesn't get connected to anything else! I would hate to think what would happen if it were to get plugged into a Commodore 64 power socket or worse, the AV output socket! The Excelerator+Plus 5-Pin DIN power socket details are shown here;
Pin 1 - 5V
Pin 2 - N/C
Pin 3 - 12V
Pin 4 - GND
Pin 5 - GND
I used a MeanWell RD-65A Power supply but you can use any 12V/5V Power Supply that can supply at least 5V at 4A and 12V at 4A. Commodore 1581 Drives do not need 12V and if you only use 1581 drives you can get away with using a single 5V Power Supply with sufficent current capacity. A surplus ATX power supply could be used, this has the advantage of the AC input of the power supply being safely inside an existing metal enclosure.
Shorter cables from the distribtion board to the floppy drives will give you less voltage drop. The 5V output on the MeanWell RD-65A can be set slightly higher to compensate for this.
The MeanWell RD-65A has AC input terminals which are exposed and could be accessed by curious fingers. It is intended to be used within another enclosure. The photos I show of my test setup sitting on a desk is NOT a recommended permanent solution. If you are not comfortable working with AC power wiring please find someone who is!
The 5V and 12V fuse values can be varied to suit your set up. While designing the PCB I sat down and measured the current consumption on each of my floppy disk drives.
1541-II 12V - Idle 0.04A - Active 0.400A 5V - Idle 0.42A - Active 0.44A
1581 12V - Idle 0.00A - Active 0.00A (it doesn't use 12V at all) 5V - Idle 0.36A - Active 0.63A
Excelerator+Plus 12V - Idle 0.29A - Active 0.36A 5V - Idle 0.56A - Active 0.56A
If I was reading/writing from all four drives at once (which is unlikely) I need a maximum of 1.16A @12V and just over 2A @ 5V... well within what a Meanwell RD-65A can supply.