Dual 3.3V, 5V, 12V power supply modules for workbench - Page 1
Forum section: electronics / projects

author: suspension
author_rank: Regular Contributor
timestamp: August 26, 2024, 05:52:10 pm
content: HelloI usually work with many projects simultaneously and having a low voltage power distribution along my workbench (which is around 20 feet long) for standard voltages is very convenient. The required voltages are +-5V, +-3.3, +-12V. Having other voltages such as 1.8, 2.5 is also helpful but not absolutely necessary. My plan is to have multiple power ports fixed to the workbench at various places each outputting a standard set of voltages.I can use standard bench power supplies for this setup, but this would require 6 of them which is too expensive. I am looking for much lower cost alternative. The currents need not be high as 99% of the time these will be used to power digital circuits. Ideally cheap power modules that can output 2-5A at these voltages will work. For example modules that use chips such as LM2596. However in order to create + and - voltages, I should be able to connect them in series. The LM2596 based ones cannot be connected in series.What other options are there? Also like to hear about other ways of achieving the same. Please note ATX power supplies will not work as they do not seem to have -5 and -3.3V voltages.Thankss

author: rstofer
author_rank: Super Contributor
timestamp: August 26, 2024, 06:17:16 pm
content: One way might be to just run +5V and use Digilent PowerBRICKS for the other voltages:https://digilent.com/shop/powerbricks-breadboardable-dual-output-usb-power-supplies/These are made to mount to a solderless breadboard so you may have to adapt the mounting.Murata make some nice DC-DC converters with multiple outputs. +-15V is handy for op amps. Search Digikeyhttps://www.digikey.com/

author: mariush
author_rank: Super Contributor
timestamp: August 26, 2024, 08:17:03 pm
content: I think that's a bit bad idea, because the longer the wires the more voltage drop you're gonna have. If you put the "low voltage power distribution" somewhere along the desk length, you may end up with 5-10 feet of wires between the sockets and the project you're working on.Make yourself a few small boxes with a barrel jack for DC input and a LM317 / LM337 pair. You can use a MC34063 to create a negative voltage from the positive voltage ... for example -18v from 16-20v input then use LM337 to make -15v.Or maybe just buy a transformer with two 15v secondary windings, add a bridge rectifier and a couple capacitors and you have your +/- 18v-ish DC.You could use a slide switch to select between +/- 3.3v , +/- 5v, +/-12v , +/- 15v or +/- adjustable (add two 10 turn pots or something like that)With the right slide switch you could also switch the feedback resistance for the mc34063 as a sort of tracking (ex if you want -5v, then convert 16-20v to -7.5v instead of -18v)

author: thm_w
author_rank: Super Contributor
timestamp: August 26, 2024, 10:47:40 pm
content: Probably have two main +12/-12V AC to DC converters, then those rails go across the whole bench. Its very easy to find 12V 5A or 10A supplies.Then buck or linear regulate each side down as needed with commonly available modules.The thing I don't like with this is the lack of current limiting and monitoring.

author: suspension
author_rank: Regular Contributor
timestamp: August 27, 2024, 08:38:39 am
content: Thank you all for valuable suggestions. While looking for MC34063 based modules as suggested by mariush, I was able to find few modules in AliExpress that fulfills my requirements:https://www.aliexpress.com/item/1005005269336203.html?spm=a2g0o.order_list.order_list_main.12.264f18026R6Pz8https://www.aliexpress.com/item/1005005510092848.html?spm=a2g0o.order_list.order_list_main.17.264f18026R6Pz8

author: mariush
author_rank: Super Contributor
timestamp: August 27, 2024, 11:28:10 am
content: You can get reasonably cheap brand name power supplies that output positive and negative voltage from places like Digikey, for example :https://www.digikey.com/short/w842m82w

author: alexk195
author_rank: Newbie
timestamp: October 01, 2024, 02:50:02 pm
content: Hi. Im currently finalizing my power supply herewww.el08.de/pps1. But it has no negative voltages and is not isolated. Do you need also higher amps on negative voltages? I suppose it's for amplifiers?

author: Randy222
author_rank: Frequent Contributor
timestamp: October 01, 2024, 05:20:13 pm
content: mains to 24vac xfrmr (toriod perhaps), bridge recitify, caps for filter, maybe a coil to take out EMI, and then just parralel some linear voltage regs (pos and neg) to get as many regulated outputs as you want, perhaps making one of then adjustable with a dial pot. Obviously the amps would be limited to the xfrmr ability.

author: Gribo
author_rank: Frequent Contributor
timestamp: October 01, 2024, 06:19:33 pm
content: Get a long DIN rail, mount it to the wall or the back plate of the bench and then get some DIN rail AC to DC power supplies. They start at ~40$. As an added bonus, you can also mount other types of DIN modules - anything from a relay board to a PC.

author: Smokey
author_rank: Super Contributor
timestamp: October 01, 2024, 08:28:17 pm
content: I'm imagining an engineer running back and forth along a 20ft bench frantically tweaking pots on tons of boards all hooked up at once.. when one changes it effects all the others... I think I've had that nightmare actually.