Suitable Power Supply for an Old Piece of Telecom Gear (+/-12V, +/-5V) - Page 1
Forum section: electronics / projects

author: W3AXL
author_rank: Regular Contributor
timestamp: January 26, 2025, 04:36:56 am
content: Hi all!I've got a vintage piece of telecom gear coming in soon (an old dispatch console with some nice VFDs) and it has an annoying set of input power requirements. Originally it came with a huge power supply brick which supplied the needed power, but these are now unobtainium.Here's what the datasheet explains is required:Obviously, I could go through the effort of designing a full PCB for this, but I was curious if anyone knows of any existing power supplies that might provide similar voltage rails. The 5V/10A in particular is annoying. I suspect that this thing probably doesn't need the full 10A (especially since each rail's capacity adds up to more than the listed 110W rating). I was looking at Eurorack power supplies since I know they have similar negative volage rail requirements, but none of them seemed to have the needed 5V rail capacity.

author: Poroit
author_rank: Frequent Contributor
timestamp: January 26, 2025, 06:04:57 am
content: G'day W3AXL,You may need to use a couple of power supplies to suit your needs.https://www.meanwell.com/productfast.aspx

author: SteveThackery
author_rank: Super Contributor
timestamp: January 26, 2025, 09:42:24 am
content: I think a standard PC ATX power supply might do the job. You can probably pull one from an old PC destined for scrap.EDIT: Oh, poop, it looks like they don't supply -5V, and the current on the - 12V line might not be enough. Sorry.

author: Haenk
author_rank: Super Contributor
timestamp: January 26, 2025, 11:14:15 am
content: Yep, I thought of a standard AT supply, but the Amperes are just not there.A stack of Meanwells should be like 75 EUR/USD, that's the best solution IMHO.

author: CaptDon
author_rank: Super Contributor
timestamp: January 26, 2025, 03:50:09 pm
content: Look on Ebay. Your power specs are well within the range of off the shelf power supplies. The +/- 12 is common for analog portions of system boards and the +/- 5 is common for intermixed logic. I am thinking of Power One or Packaged Power and who was the power supply manufacturer with the rearing horse as their logo?? You should very easily be able to find your need in both analog and SMPS configurations on Ebay.

author: W3AXL
author_rank: Regular Contributor
timestamp: January 26, 2025, 06:52:37 pm
content: I'm currently thinking about making a small box which can take in 12V and create -12V with one of those isolated DC-DC modules, and then regulating down to 5V and doing the same thing for the -5V. Biggest challenge is going to be the 5V10A rating but that's not a crazy amount of power.The benefit of this is that I can run it off of either straight 12V from a battery/bench PSU or a standard AC/DC PSU.

author: edavid
author_rank: Super Contributor
timestamp: January 26, 2025, 08:34:32 pm
content: Check out arrow.com, they have some good closeout deals on CUI brand OEM power supplies. Even with the 67% tariff, you can put together what you need quite cheaply.https://www.arrow.com/en/manufacturers/cui-inc/power-supplies/ac-to-dc-power-supplies?promoGroupLevel=main&filters=In+Stock:Yes;&sortBy=calculatedPrice&sortDirection=asc