switchmode powersupplies in parallel  - Page 1
Forum section: electronics / beginners

author: combatplayer
author_rank: Contributor
timestamp: April 14, 2017, 09:40:59 am
content: hey everyonei'm working on an amplifier for my TV setup, and to power it i need a relatively high output 24v supply. but due to my own stubborness and limited funds, i ended up with a relatively small enclosure. the only 24v supply i've found that fits only delivers a portion of the power i need. i'm looking at this supply:http://www.banggood.com/AC-DC-Switching-Power-Supply-Module-AC-100-240V-to-DC-24V-9A-Power-Supply-Board-p-1086527.html?rmmds=mywishlistnow, having read a lot of topics online about this, they all seem to be saying either "dont do it" or "at least add a diode" of which i'll be adding a diode, a large 10a one per supply.the issue i'm facing is that these supplies barely drop at all in voltage till they reach the cutoff point and shut down, and i'm not equipped to calibrate them to within an inch of eachother, which would also require modding as they dont have adjustable output.now, is there a way for me to induce a voltage drop when they reach the 5-6a output level so the other supply will start outputting power or is there a completely other solution i haven't thought of?the total output i need is at least 250 watts continuous at 24v (22-26v, can be AC but the peaks musn'te go above 26v), my enclosure is a little weird in its construction and has screws preventing utilization of the entire area, but the longest it'll allow for in any direction is 19,5 x 15 x 4 centimeters, smaller is better.i will be adding active temperature controlled cooling, but it will be tied to the temperature of the amplifier as opposed to the powersupply.Here's a rough sketch of the project with the two powersupplies in the bottom:https://www.tinkercad.com/things/c18TAlTZGk4-amplifier-box/editv2Edit: price preferably low

author: tszaboo
author_rank: Super Contributor
timestamp: April 14, 2017, 10:27:32 am
content: Just place the power supplies in series. I dont know how many power supplies you need, but you could put 2x 12V or 3x8V, and be done with it. Place a diode "normally not conducting" parallel with each supply.

author: combatplayer
author_rank: Contributor
timestamp: April 14, 2017, 10:36:26 am
content: sadly i failed to find a 120+w 12v powersupply that was small enough for me to fit two of them. i've also read that there's more risque involved in putting cheap supplies in series, is that something you have experience with?

author: danadak
author_rank: Super Contributor
timestamp: April 14, 2017, 10:37:35 am
content: Paralleling power supplies, weather linear or switch mode, havea number of considerations -http://www.switchpwr.com/parallel.pdfRegards, Dana.

author: combatplayer
author_rank: Contributor
timestamp: April 14, 2017, 11:53:24 am
content: i've read the document, i dont believe these supplies are capable of being wired through the third wire method, unless thats modable (?) and the two others require trimming of the voltage. if nothing else can be done, i suppose i will come back later and ask about how to mod the supply to have adjustable output.

author: tszaboo
author_rank: Super Contributor
timestamp: April 14, 2017, 12:18:51 pm
content: OK, instead of jury rigging stuff, you can just buy this.http://eu.mouser.com/ProductDetail/Mean-Well/EPP-300-24/?qs=%2fha2pyFaduhTgKandwNLmqImEDH95rGZqmHhm0lDcgw%3dYou own me a beer.

author: combatplayer
author_rank: Contributor
timestamp: April 14, 2017, 01:24:20 pm
content: that's a very nice supply, very fit for the project. it's more than twice the price of the rigged solution though.i'll have to think on that for a little while.Thanks for the help!

author: maukka
author_rank: Unknown
timestamp: April 14, 2017, 01:46:57 pm
content: Quote from: combatplayer on April 14, 2017, 09:40:59 amThat PS looks like the ones that are warned against here:https://www.aliexpress.com/store/product/RD-DPS3012-Constant-Voltage-current-Step-down-Programmable-Power-Supply-module-buck-Voltage-converter-color-LCD/923042_32685179404.htmlQuote from: RD

author: combatplayer
author_rank: Contributor
timestamp: April 14, 2017, 03:21:43 pm
content: ah thanks for the warning.. so there really is no cheap solution?