Bipolar PSU Proofreading


#1

I’m seeking to create a discrete bipolar power supply for testing DIY eurorack modules. While I’m aware that this has already been covered with the Module Tester, I still find myself wanting to use a separate supply dedicated to the power side of things. Will this cover it?


Are there any caveats I can expect in regards using this for the purpose of eurorack testing?


#2

Looking at the LM2575 datasheet, your schematic looks good. Were you able to build it? I’m interested in the power supplies.


#3

Yeah, I’ve used this circuit to power a breadboard’s rails with great success. The difficulty, especially as a mere hobbyist, lies in assessing what amperage this circuit is capable of providing.
When using a wall wart to supply a separate supply circuit the efficacy of the power supply begins to swing about a double ended pendulum of sorts. It’s likely not the supply you’d want to use to finalize a design, but it is inexpensive and consists of relatively few parts.


#4

There must be some sort of golden rule for datasheets, ie. a percentage of what they claim is capable. I’d always personally stick to about 75%. Over-rating something is sensible unless you’re in the business of mass production.


#5

I tend to err on this side of caution with the ratings of PSU components and treat 60% of the rated value as my max.

There is an old Electro Notes article on PSU design which is very useful http://electronotes.netfirms.com/PS.PDF

And also a post on the Electro-Music forum http://www.electro-music.com/forum/topic-27668-0.html&postdays=0&postorder=asc&highlight=


#6

Thanks for the incredible resources rumblin_cynth_rampo. Incredible.


#7

I just did my take on a switch-mode power supply. Ordered the boards and components, will assemble as soon as they arrive.


#8

Nice small PSU @smotesko! But since there are less and less modules that need +5V (and funnily at the same time more and more PSU that provide +5V), I would rather have one DC-DC converter dedicated for +12V and the second DC-DC converter for -12V. And then maybe a small third converter for +5V (some murata in 7805 compatible packaging).


#9

Yes there’s a tendency to regulate 5V down from +12V line, while most modern PSUs provide 5V supply. I don’t understand it. But I’m designing my own modules and also will be building some kits, so I can modify the digital module kits to make them use the 5V line.