One power supply into two. - Page 1
Forum section: electronics / projects

author: vini_i
author_rank: Regular Contributor
timestamp: July 22, 2016, 11:08:03 pm
content: There is along story parts of which i'm not allowed to tell but there are some specific reasons why i'm doing what i'm doing.I have a piece of industrial equipment that has an adjustable DC power supply in it (0-150VDC 0-7A). I need to turn that supply into two independent 33VDC 1A supplies. It doesn't have to be accurate but it needs to be really stable. 4mV p-p or better would be acceptable ripple but better would be well better.What i was hoping to find is something maybe LM317 based power supply that i could feed DC into and get a lower DC out. Can't find a thing. This would be a DC to DC supply but searching that only brings up switchers which can't meet my requirements. I could spin my own supply but characterizing it and qualifying it would take too long. I'v found a few home built and Chinese supplies with LM317 but they have the same problem as the home spun.Where could i find an LM317 based power supply or something similar from a quality manufacturer? What could i search for other than DC to DC?

author: Skimask
author_rank: Super Contributor
timestamp: July 22, 2016, 11:13:51 pm
content: You make a switcher that's noisy but gets you down to something like 40V, then go linear down to 33V.And the LM317 only really cares about the Input->Output differential. Doesn't matter if it's dropping 20V to 5V, or 100,020V down to 100,005V. So, you could go 150V->120V->90V->60V->33V. A bit on the complicated side, but simple and gets the job done.

author: tautech
author_rank: Super Contributor
timestamp: July 22, 2016, 11:17:34 pm
content: That will be straightforward enough unless you need to retain adjustability of your 170V PSU, you don't say.LM317 datasheet:http://www.ti.com/lit/ds/symlink/lm317.pdf

author: vini_i
author_rank: Regular Contributor
timestamp: July 22, 2016, 11:18:34 pm
content: The power supply is adjustable. I can turn it down to 40 or 45V, that's not the issue. I'm trying to find a prebuilt and characterized LM317 or similar power supply.

author: tautech
author_rank: Super Contributor
timestamp: July 22, 2016, 11:23:32 pm
content: http://www.ebay.com/itm/LM317-LM337-Adjustable-Voltage-Regulator-Dual-Power-Supply-Board-1-25-37-5V-/182106909574?hash=item2a666aeb86:g:m7UAAOSwM0FXHr~S

author: vini_i
author_rank: Regular Contributor
timestamp: July 23, 2016, 01:16:51 am
content: Would you be aware of anything like that but from a more respectable source?

author: tautech
author_rank: Super Contributor
timestamp: July 23, 2016, 01:20:44 am
content: Quote from: vini_i on July 23, 2016, 01:16:51 amNot at that price.

author: Delta
author_rank: Super Contributor
timestamp: July 23, 2016, 01:25:10 am
content: You also need to define "independent". Would two liner regulators hanging off the same supply count?

author: vini_i
author_rank: Regular Contributor
timestamp: July 23, 2016, 01:34:46 am
content: Quote from: tautech on July 23, 2016, 01:20:44 amI'd be willing to pay up to $500 for this supply from a respectable manufacturer.Quote from: Delta on July 23, 2016, 01:25:10 amTwo liner regulators hanging off one supply would be perfect.