High-quality, "medical-grade" power adapters -- your recommendations needed! - Page 1
Forum section: electronics / general

author: 13hm13
author_rank: Frequent Contributor
timestamp: May 09, 2020, 02:46:09 pm
content: I have an ELPAC wm080 linear 24V adapter*, that has been in always-on use since 2008 (!!). It has never failed. Yesterday, I disassembled it to look at its internal construction and condition. The orig. electro caps all measure very well with low ESR and leakage.ELPAC is now part of "Inventus Power" and they no longer make linear power supplies/adapters . They're all SMPS.Anyway, I'm looking into replacing several of my around the house and around the lab PSU adapters with higher-quality replacements. I'm told to use key words such as "medical grade" to narrow my Google search.Specifically, I'm looking for single-volt adapters for:5V, 9V, 12V, 20V and 24VOther than ELPAC, I've heard positive things about MEAN WELL (China) and Mascot (Norway).Please recommend some manufs or brands.*That ELPAC 24v linear was orig. recommended on several audio forums.Refs:https://inventuspower.com/products/power-supplies/premium-elpac-brand/https://www.amb.org/forum/alternative-wall-wart-for-m3-other-than-elpac-wm080-1950-76-t770.htmlhttps://www.pinkfishmedia.net/forum/threads/lm117-317-datasheet-tracking-pre-regulator.44928/page-6#post-1642669

author: TERRA Operative
author_rank: Super Contributor
timestamp: May 09, 2020, 02:51:28 pm
content: TDK Lambda is another top-tier PSU manufacturer to look at.

author: Karel
author_rank: Super Contributor
timestamp: May 09, 2020, 04:22:51 pm
content: We have bought many medical approved desktop adapters 60 Watt 19 Volt (notebook style) to power our medical devices.Leakage current is less than 100 uA @ 253 VAC.They don't have a ground terminal, they use a IEC320/C8 connector.We tested them all, one by one, with a leakage current tester, and every two years they come back again for re-testing.So far they never failed.https://www.cincon.com/productdetail/TR60M.htmlThere are also these wall-adapter style powersupplies (without ground terminal):https://www.cincon.com/productdetail/TR15RAM.html

author: 13hm13
author_rank: Frequent Contributor
timestamp: May 09, 2020, 04:48:54 pm
content: Thx for the suggestions and replies!Coming from an "audiophool" background, one std. practice I use is the use multiple line conditioners.Even for non-audio equip. (computers, etc) , I think power cond. makes a difference in operation and reliability. So, fewer HDD crashes/failures, fewer computer lock-ups or freeze-ups.My layered approach to pwr cond:Chang Lightspeed --> APC UPS --> Tripp-Lite Isobar.Also, I use a fair amount of ferrite beads.

author: 13hm13
author_rank: Frequent Contributor
timestamp: May 09, 2020, 07:48:13 pm
content: BTW: I used the keywords "medical grade" in quotation marks in this thread's title. That how marketing and industry describes their higher-quality products.I am not nor have I ever been affiliated with the medical industry.I'm just curious about higher-quality products and their design.

author: chris_leyson
author_rank: Super Contributor
timestamp: May 09, 2020, 08:56:12 pm
content: Meanwell are good for off line medical grade supplies. If you want medical grade DC-DC converters then TRACO.

author: Buriedcode
author_rank: Super Contributor
timestamp: May 09, 2020, 09:03:29 pm
content: Quote from: 13hm13 on May 09, 2020, 04:48:54 pmIf you're getting hard drive issues, and its because of the mains, I think your PC/laptop will have much bigger issues as it's own power supply should be able handle a wide range of voltages, and mains "noise". In the case of laptops power goes through two SMPS's to power the drive (external charger brick + on board SMPSs for all the rails). If you're computer is "freezing" because of mains supply, then your mains must either be dropping out, or sagging significantly in which case no amount of filtering/conditioning will help.

author: chris_leyson
author_rank: Super Contributor
timestamp: May 09, 2020, 09:16:05 pm
content: Medical grade are low leakage, uA range, better still if you get them down to sub uA but now you are talking pF range coupling capacitance for off line supplies. Don't think low leakage supplies are going to solve your problem, sounds like you need more bulk capacitance.

author: 13hm13
author_rank: Frequent Contributor
timestamp: May 09, 2020, 10:18:16 pm
content: The ELPAC linear adapter I noted in the top post was merely "okay" in internal build quality.It uses some weird Sharp Electronics 4-pin reg. The PCB seems quite good -- thick with good traces.One thing I noticed was no X-Y cap on the mains input, so I added one.While the stock ELPAC is a decent and reliable device with low ripple/noise, us audiophool tweakers are never satisfied.I did replace both Wun Hung Lo electro caps with Panasonics.Maybe I'll replace the std. plastic diodes with avalanche Sinterglass from Vishay. Have several of those left over from a prev. project.https://www.vishay.com/docs/86098/about.pdfBTW: The primary use for the ELPAC is a headphone amp.

author: Karel
author_rank: Super Contributor
timestamp: May 10, 2020, 06:35:34 am
content: Some time ago I noticed a patent describing the following setup in order to get lowestpossible leakage current while keeping full isolation.That setup uses two converters. The first one is an AC/DC-converter that converts the linepower 100 - 230 VAC to 12VDC.One of the outputs is connected to (a clean) earth. Then a DC/DC-converter is used to convert from 12VDC to 12VDCin order to create full isolation from earth.I guess this is the best possible setup. The only better solution is battery operation.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: May 10, 2020, 12:47:51 pm
content: "Medical grade" is not marketing wank. There are real specifications for this.Part of this specification is low leakage current, as already mentioned.Other part of the specification is higher isolation strength, I think it's 5kV instead of the more regular 2kV.Yet another part of the spec is that if one component fails, it does so in a way that no dangerours voltages may appear on the output. Sometimes High voltage caps are put in series to prevent a short when one cap fails.Often there are also extra precautions against over voltages on the output, for example with a crowbar that blows a fuse.There may be other specs, and they will also vary in different parts of the world.

author: Karel
author_rank: Super Contributor
timestamp: May 10, 2020, 01:16:14 pm
content: https://www.xppower.com/applications/medical-power-supplieshttp://medicalitech.com/images/practical-guide-to-iec-60601-usa-min-min.pdf