Looking for a good 10A Variable DC Power Supply - Page 1
Forum section: electronics / general

author: echomancer
author_rank: Contributor
timestamp: August 17, 2012, 02:14:52 pm
content: I have been building a lot of solar powered items. I need something that can simulate output from solar panels up to 10A of current. I'm primarily working in voltages from 12-18. I have found this Mastech unit on EBay, but it just seems too cheap, given that their 5A model is only $20 less than this: (http://www.ebay.com/itm/HY3010E-Adjustable-Variable-0-30V-0-10A-Lab-Grade-Pro-Ditigal-DC-Power-Supply-/110906187630?pt=LH_DefaultDomain_0&hash=item19d2861f6e#ht_2271wt_1144.Having a fixed 5V output would also be helpful.I am in the US. Thanks in advance for the help!ETA: I am looking to keep this under $300 - $400. I would LOVE to get the Rigol 160Watt version, but that's way out of my price range

author: DarkPrince
author_rank: Regular Contributor
timestamp: August 17, 2012, 02:42:57 pm
content: Just a question, but would it not be possible to properly simulate a solar panel with a standard power supply as a panels response is more... complex? A simple series resistor wouldn't suffice, IMHO. To extend, sounds like an interesting project.

author: maiakaat
author_rank: Regular Contributor
timestamp: August 17, 2012, 03:34:11 pm
content: (unrelated HP bench PSU)http://www.ebay.co.uk/itm/290759974129?ssPageName=STRK:MESINDXX:IT&_trksid=p3984.m1436.l2649#ht_500wt_1413Mastech don't have a very good reputationI bought a cheap PSU a few years ago, (different brand) it was faulty on arrival, and I repaired it recently, (despite having another) and it lasted 5 minutes, it was physically damaged on arrival, and despite being advertised as new it had two different screws mounting a cheap plastic support, which snapped shorting out the supply on the case. After repairing this, in the hope of a second supply for occasional use it went again within 10 minutes, some different fault, no fuses blown. I had a refund on the supply, and have a decent switching PSU to make up for it.Most of the precision stuff from china seems to have terrible specs, so I doubt it is worth the money.

author: SeanB
author_rank: Super Contributor
timestamp: August 17, 2012, 03:55:28 pm
content: My solar panel simulator is a 16VAC transformer with a bridge rectifier across the secondary, and around 15000uF of smoothing. The controller is fed from this via a 12V halogen downlight, either a 20W or 50W unit in a holder. Simulated the panel nicely, and is short circuit proof, as the lamp will blow for prolonged shorts.

author: T4P
author_rank: Super Contributor
timestamp: August 17, 2012, 03:57:03 pm
content: Right ... Mastech doesn't have a good reputation TO YOU!There a couple of threads here that mastech are the original low-end PSUs as an alternative of this ageThese are not precision stuff no matter how you think if you think the mastech MS8218 are not precision enough, go elsewhere where the martians welcome you

author: saturation
author_rank: Super Contributor
timestamp: August 17, 2012, 03:57:55 pm
content: Have you checked the archives and posts on Mastech? Quite a number of them and with good reviews, but beware of possibly fake Mastech. In the USA the only one I'd trust to get one is the dealer in CA:http://www.mastechpowersupply.com/variable-power-supply/linear-power-supply/cat_6.html

author: maiakaat
author_rank: Regular Contributor
timestamp: August 17, 2012, 04:41:25 pm
content: Daves view of Mastech seems to be that they are best avoided as a precautionSorry I didn't put that it was my opinion, I shouldn't have stated it as a fact, I don't think I deserve the shout-down.I can't say I feel that welcome on these forums so far, I might just go back to learning and figuring things out on my own, and not bothering to offer any opinions or experiencesI hope I am not representative of the average female who tries to get involved with electronics, there is no need to be so aggressive

author: maiakaat
author_rank: Regular Contributor
timestamp: August 17, 2012, 05:00:12 pm
content: I doubt there is an internet connection, lab or anything else there for me to want to go to Mars for, aside from the toxic environment. Although hopefully curiosity will find some interesting stuff there regarding elements.As an additional note, if some alien race welcomed me, I'd go, they are far more technologically advanced than we are if rumours are true that they exist, and if the human race doesn't destroy themselves, I'm sure the aliens will be much more tolerable and less hostile judging by their rumoured conduct so far, compared against my experiences on the earth at times.

author: T4P
author_rank: Super Contributor
timestamp: August 17, 2012, 05:05:24 pm
content: Don't be too worried, i'm very outspoken if i may, we most certainly welcome anyone male or femaleI understand your point but Mastech is a very good chinese company if ever,Real Mastech's have good quality and that's just it.Certainly those PSU's were not meant to be precision at all so of course if any precision i would use a HP 6632AI wouldn't be too worried about voltage shift on a general use PSU

author: maiakaat
author_rank: Regular Contributor
timestamp: August 17, 2012, 05:43:07 pm
content: Mastech did initially impress me (handheld multimeters) but after some of Dave's stories, the long term reliability needs to be proven for me.There is a lot of bad PSU's out there so its better to be sure of a product you buy, or know you will have no problems returning it, like some advice says, use a reputable seller (for example the UK has a 14 day grace period for internet purchases, and good protection for misleading sales, but only if your shipping costs to return are a UK company and not somewhere far away without the same obligations)Once you add on tax and customs charges it rarely is a saving in the UK for larger products.There's lots of great value design aids, such as low cost TSSOP PCB's and things from Asia though, fantastic value, and its known a good number some ODM's are from Chinese design and manufacturing teams.Somewhat off topic though this post, in places

author: saturation
author_rank: Super Contributor
timestamp: August 17, 2012, 08:15:28 pm
content: I bought a Mastech over a year ago, and its been fine; its also a good performer using Agilent's test suite for PSU.Longer term reliability is anecodotal, but in the USA, folks from the RC community have been buying Mastech supplies from the URL I posted earlier since early 2004. So, there is a past history of good performance; if you read their forum and their skill level, it has survived being abused.However, with brands being dubious and potentially even counterfeited by other China factories, I can't say about all Mastech branded PSU in other countries.http://www.rcgroups.com/forums/showthread.php?t=192034If I bought one, I'd tear it down and examine the build quality, there are many photos in the eevblog and rcgroups archives of internal appearances. There are comparisons between less good PSU on this forum, Yihua as example.Quote from: maiakaat on August 17, 2012, 05:43:07 pm

author: grumpydoc
author_rank: Super Contributor
timestamp: August 18, 2012, 08:41:42 am
content: I have an IsoTech branded dual 0-30V @ 3A plus fixed 5V - so far it's been trouble free. I've also fixed a couple of the 20A units. Internal construction is OK(ish) - certainly niggles such as exposed mains inside but not too many horrors.My biggest grip, though - apart from the continuously running fan - is the lack of overvoltage protection. I get the impression that they're generally reliable so the ones that have passed through my hands for repair are probably the exception rather than the rule but they are certainly capable of putting out an unregulated 52V if the power transistors develop a short. In the 20A unit this is backed by a pretty beefy toroidal transformer so any 3.3V or 5V stuff on the output will probably fry. This has happened to two of the three that I've repaired. the third has blown ALL its output transistors O/C & I'm waiting for replacements. I did consider swapping the 2N3055's for 2n3771's until I saw the price of the latter

author: Rerouter
author_rank: Super Contributor
timestamp: August 18, 2012, 08:57:41 am
content: 2n3771's would be un-ideal anyway, at a guess it would be the breakdown voltage killing your supplies, with the 2n3055's only capacle of 60V, perhaps these insteadhttp://au.element14.com/on-semiconductor/mj15015g/transistor-npn-to-3/dp/9556486yes they are double the price but should be much harder to kill,

author: grumpydoc
author_rank: Super Contributor
timestamp: August 18, 2012, 10:15:29 am
content: Yes, thanks - that does look a better bet, even a smidge cheaper than a 2n3771 from Farnell in the UK.You're probably right about the breakdown voltage - the PSU design does include a set of relays so that the unregulated DC tracks the regulated output somewhat but I suppose the potential does exist for >50V across the output transistors. For some reason I had 120V in mind for the 3055 and assumed the 3771 was similar - didn't realise it was actually only 60V & 40V.

author: activevisual
author_rank: Newbie
timestamp: August 20, 2012, 06:05:11 am
content: I have my own IsoTech branded dual 0-30V @ 3A plus fixed 5V - so far it's been trouble free. I've also fixed the 20A units. Internal construction is good- certainly niggles such as exposed mains inside but not too many horrors.http://www.ebay.co.uk/itm/Bench-Power-Supply-Thurlby-Thandar-TTi-PL330QMD-Dual-Output-32-64V3-6A-/180949303459?_trksid=p4340.m1850_trkparms=aid%3D222002%26algo%3DSIC.FIT%26ao%3D1%26asc%3D11%26meid%3D452969797079906918%26pid%3D100011%26prg%3D1005%26rk%3D3%26i think it is best for you ..this is with in your budget...Audio Systems