Beefy, linear power supplies - Page 1
Forum section: electronics / beginners

author: David Aurora
author_rank: Frequent Contributor
timestamp: March 22, 2012, 11:53:02 am
content: I posted a while back about the interesting experience I've had with Queensland electrical licensing trying to be able to legally build things. I've been back and forth with them a bunch of times and gotten absolutely nowhere. They just flat out can't comprehend that there's a big difference between Joe Blow wanting to wire up his house to save a few bucks and an electronics enthusiast like myself wanting to build a good quality, safe power supply rather than buy the nasty, dodgy pieces of shit sold in stores.I mostly make audio gear, and without spending stupid amounts of time and effort on filtering, switch mode is absolutely useless to me. Which is all that seems to be on the market these days. The AC plug packs I've seen readily available that class as ELV don't give me the options I'd like for rolling my own DC supply (like having a centre tap, higher current, etc). For the amplifier project I'm working on at the moment, I could go a minute down the road to Jaycar and pick up a suitable transformer any time I want (or pick it up for half the price online haha, but that's another story...). But, of course, I'm not technically allowed to plug it in.So I'm trying to follow the rules and use a wall wart here, but the only ones I can find require me to scale my design down to the point where it's power output is completely useless to me. But I know over the years I've bought products that came with with external, good quality, high power supplies, and AC supplies with centre taps and all kinds of things, but I can't seem to find where to buy them. All the usual suspects I know for electrical gear seem to just flog cheap chinese SMPS's or really low power AC plugpacks that aren't what I'm after. Any tips where to look? Basically what I really want is a transformer in a box essentially, so I can do my own rectification/filtering and so on but without breaking QLD law by connecting a transformer myself.

author: DonRon
author_rank: Regular Contributor
timestamp: March 22, 2012, 12:20:26 pm
content: Hi David,maybe this is the right stuff. But it is a german company - don't knew if you can get the units in australia.http://www.statron.de/details/179They got a bunch of high power ac supplies, but you have to pay for it.There is another german company and i have seen that farnell is selling these products. But i cannot find those beefy ac-supplies at their page.http://www.elektroautomatik.de/en/products.htmlCheers,Ronald

author: David Aurora
author_rank: Frequent Contributor
timestamp: March 22, 2012, 12:23:24 pm
content: Thanks mateNot quite what I meant though. What I'm after is more plug pack style, a portable thing to use with a device rather than a bench type supply

author: DonRon
author_rank: Regular Contributor
timestamp: March 22, 2012, 12:28:33 pm
content: What output voltage and amp's do you need?

author: sonicj
author_rank: Frequent Contributor
timestamp: March 22, 2012, 12:31:37 pm
content: scrapyard.not exactly in a "case", but its big and linear!-sj

author: David Aurora
author_rank: Frequent Contributor
timestamp: March 22, 2012, 12:35:04 pm
content: sonicj-Quote from: DonRon on March 22, 2012, 12:28:33 pmIdeally I'd like to find a place with options. Right now, ideally I'd like 30VAC with a centre tap, and about 3 amps. But yeah, more of a general question for good sources of decent quality supplies

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: March 22, 2012, 03:59:07 pm
content: QuoteThe jurisdiction of people who govern wiring regulations typically ends at the wall socket. Anything beyond that is generally covered by product standards, but often only if you are selling the product.QuoteI very much doubt this is the case. I'm not familar with Aus, but I don't recall ever seeing regs governing homebuilt things that plug into standard wall sockets in non-commercial situations.As I said, if it's not a product, and not permanently wired into the supply, chances are nobody cares.

author: David Aurora
author_rank: Frequent Contributor
timestamp: March 22, 2012, 04:18:30 pm
content: Quote from: mikeselectricstuff on March 22, 2012, 03:59:07 pmLogically, you'd think that's the case. And a lot of people assume that (like I originally did). But when I started asking the authorities questions so I knew what I needed to do in future if I want to sell things I've built, or repair things, it turns out the law here sucks. I've now lost count of the phone calls and emails back and forth between myself and the licensing people, but I've been told in no uncertain terms that I'm not allowed to touch anything other than the low voltage side of a wall wart (and the only way to get licensed is a 4 year apprenticeship). There's plenty of old wives tales about workarounds and whatnot, but I've gone at this from every conceivable angle when talking to the authorities and every single time they tell me no dice.And I'm not publicly saying I have of course... but theoretically speaking... one could wire up whatever they want at home and nobody needs to know. And it wasn't me... but a friend of a friend of a friend quite possibly has a prototype working beautifully already on his bench, running off a home made power supply that is perfectly safe and was built from parts bought perfectly legally from a store right down the road.But I'm just tired of endlessly looking for a solution here and getting nowhere. I've (err... I mean someone I once met...) built piles of cool stuff, and none of it has electrocuted anyone or set fire to any pets or liberated any magic smoke or anything. But when people I know (err... my friend knows...) ask if I (they...) can build them one the only answer possible is "Am I capable? Of course. Can I/Will I? Nope. Not allowed, not going to risk it". I'm over it. I just want to find a solution and build stuff that can be used outside my garage.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: March 22, 2012, 04:40:48 pm
content: QuoteHave you asked them precisely which regulations prohibit it? If they are saying it's not allowed they must be bale to say exactly why. In some cases, people don't actually understand the regulaitons they police, especially in nonstandard cases, and it can be worth referring back to the actual regulations in question.In practice I really wouldn't waste time worrying about it - if it's for your own use nobody will care unless you actually manage to kill someone.

author: metalphreak
author_rank: Frequent Contributor
timestamp: March 22, 2012, 04:51:47 pm
content: To make things worse, I believe it's all governed by state law, not national law, so it varies all across Australia

author: David Aurora
author_rank: Frequent Contributor
timestamp: March 22, 2012, 04:56:23 pm
content: Quote from: mikeselectricstuff on March 22, 2012, 04:40:48 pmBingo. For the last round of discussions I had with them they had to pass me through 4 or 5 people to answer my questions because they were "Too technical". And as you can probably guess, they weren't actually very technical questions at all.The laws are outlined here-http://www.justice.qld.gov.au/fair-and-safe-work/electrical-safety/law-and-penalties/electrical-safety-legislationThere's so many vague as fuck bits in there, completely open to interpretation. And of course, they won't clarify anything, they just quote/copy/paste generic text and try to move you along.Look, honestly, I'm not too concerned about it as far as dicking around on my bench goes. I make things to a higher safety standard than they prescribe, one I call "Common sense". But at the end of the day, I'm not one of those guys who wants to sit around with an Arduino patting myself on the back for flashing an LED. I like inventing. I like building things that make loud noises. And ultimately if I want to share any of these things with the outside world (even just to blog about it or whatever) I'd like to know I'm not going to get slapped with a fine for doing so.So yeah, just to clarify- I'm with you. I think it's ridiculous, and I'd like to just ignore it all and build stuff. But for the reasons above, I'm looking for an alternative in the power supply department.Quote from: metalphreak on March 22, 2012, 04:51:47 pmYep

author: David Aurora
author_rank: Frequent Contributor
timestamp: March 22, 2012, 05:02:46 pm
content: P.S. Just to point out that I'm not being overly paranoid here, I've actually had staff from the licensing department look me up on the internet when I've asked questions and come back with responses basically going "You're a musician, what the hell business do you have asking about electrical laws"

author: Bored@Work
author_rank: Super Contributor
timestamp: March 22, 2012, 05:06:05 pm
content: Quote from: David Aurora on March 22, 2012, 11:53:02 amThe usual way to send bureaucrats a wakeup call is to let a lawyer send them a letter. But of course that doesn't come for free, and has the severe disadvantage that you need to come in close proximity to a lawyer. Typically a lawyer's letter is not processed by the bureaucrats you initially dealt with. Sometimes these have more clue.

author: David Aurora
author_rank: Frequent Contributor
timestamp: March 22, 2012, 05:13:27 pm
content: Quote from: BoredAtWork on March 22, 2012, 05:06:05 pmI think we all know that unless you're incredibly stupid and careless, you're far more likely to die from a car crash or a falling vending machine or probably even goddamn bird flu than you are by connecting up a transformer. But yeah, I don't have any spare cash for a lawyer to take that suggestion, so for now I'm stuck abiding by the laws as they've explained them to me

author: T4P
author_rank: Super Contributor
timestamp: March 22, 2012, 06:15:40 pm
content: Offtopic .Because there isn't any rules here governing such bullshit since there aren't many ( i shall say , just a little away from None ) a little crazy ( crazy as in inventor wise ) hobbyist that has a serious going ,i blow shit up , i love burning things with current and voltage , plasma is my love , loud noises .I would just say that's me , everytime i burn something up i need to go grab another "protection sheet" .Electronics is not a don't dare , don't do thing . It's a thought-of , must try . Fair enough if you know that some bollocks from the station is gonna slap you a fineBut for me i just love to blow damaged regulators up !Do not attempt the same stunts i do on the same table i work on , i got a few burns and shocks a few times but you could do a hell lot worse , beginners .Oh , Dave Aurora , they said you are a musician , was there a chance that you were on DIYstompboxes.com forum ?I was there before i was here , i was really interested in electronics 2 years ago after i bought my Strat .

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: March 22, 2012, 07:19:09 pm
content: QuoteTypical civil servant mentality - only capable of thinking about one thing.That quote is almost worth a formal complaint....

author: nukie
author_rank: Frequent Contributor
timestamp: March 22, 2012, 10:14:58 pm
content: Find a sparky, let him do the inspection and have him sign off your work. Does that work?

author: David Aurora
author_rank: Frequent Contributor
timestamp: March 23, 2012, 03:16:30 am
content: Quote from: Dave.S on March 22, 2012, 06:15:40 pmMaybe I should move hahaI think I might have an account there that I've never used. I think I went looking for a schematic for a blown up pedal once or something and had to sign up to see it.Quote from: mikeselectricstuff on March 22, 2012, 07:19:09 pmIt actually crossed my mind at the time but then I wondered how moronic the next level up would beQuote from: nukie on March 22, 2012, 10:14:58 pmNot really. The whole point of looking for these power supplies is to simplify the process. Getting a sparky out every time I build a low voltage box of something would be a nightmare, and realistically it still wouldn't legally entitle me to sit around plugging it in and working on it for prototyping/testing purposes or anything anyway.

author: ondreji
author_rank: Contributor
timestamp: March 23, 2012, 11:40:03 am
content: I think you gan get special license in AU. Special in sense that you can plug your stuff in to the mains...Ok, it's called "Restricted electrical work licence" and you have to one of the recognised trades:http://www.justice.qld.gov.au/fair-and-safe-work/electrical-safety/electrical-workers-and-contractors/licencing/classes-of-licences#restricted

author: David Aurora
author_rank: Frequent Contributor
timestamp: March 23, 2012, 01:26:29 pm
content: Quote from: ondreji on March 23, 2012, 11:40:03 amRestricted licenses can allow you to replace certain parts under certain conditions, but don't allow you to build your own stuff or modify things

author: G7PSK
author_rank: Super Contributor
timestamp: March 23, 2012, 06:40:25 pm
content: Can you not use a site isolation transformer, Like they use on building sites here in the UK 240 in and 110 with center taped earth out, so only 55 volt above earth potential.Here's a link.http://www.wattbits.com/catalogsearch/advanced/result/?search_category_id=717&extended_range=0&order=price&dir=asc

author: ondreji
author_rank: Contributor
timestamp: March 23, 2012, 11:12:54 pm
content: Quote from: David Aurora on March 23, 2012, 01:26:29 pmStrange... Anyway, I had subject on uni and after passing final exam I was allowed to- work on mains but I have to be supervised and after few years (2 or 3) I can get full license- "design mains powered prototypes" or something like that-- basically it allows what you wantI think there must be a way -- how can researches / students / startups create innovative devices?

author: Rerouter
author_rank: Super Contributor
timestamp: March 24, 2012, 12:45:55 am
content: I will just say what i have seen as something that passes most of there crap,having an isolation transformer that is fused on the mains side and put to an IEC socket so that no cord leaves the device and in a way that the mains cannot be accessed unless done deliberately (e.g. someone cant poke something into a hole by accident and hit bare wire on the mains side)basically fuse and isolation tansformer means you cant hurt the power grid, and there is a limit on the supply of how much power can be passed,the socket and protection against stray pieces of metal means that you don't have to worry about all the BS of getting your cord certified and makes it so the only way an accident can occur is of someone deliberately tampered with it, (also the socket means your cord cant be chopped and is likely to be salvaged later on, keeping it alive)if the case is metal, tie it to mains earth, and being a power supply bring earth to another binding post on the front, and tie your internal earth to mains with a 1M resistor or higher, this covers all sorts of BS about charge equalisation of floating supplies,as for the internals, the same old basics, make sure if there is something able to produce lethal or hazardous voltages make it so they cant be accidental bumped, or have a stray piece of copper come through a vent and short them out to external parts, and making sure there is some limit of current so you cant have it start fires with shorts,and as a final note, if the heatsink is going to get F'ing hot, put a warning label or something near it, or a shroud to stop people touching it by accident, e.g trying to unplug it after hard use,

author: gregariz
author_rank: Frequent Contributor
timestamp: March 24, 2012, 02:22:28 am
content: Quote from: David Aurora on March 23, 2012, 03:16:30 amMy understanding is that in Aus paying a sparky to sign off is actually your only option. There are no alternatives to the apprenticeship route. There have been many discussions over the years.It wasn't clear to me whether you wanted to sell the amplfiers or not but if you are interested in sale to the public in some quantity, you'd probably be better off doing it in asia and seeking product certification through a test lab to import. Also if you are manufacturing amplifiers to sell you would also need C-Tick (EMC), also tested through a test lab.You could offer it for sale as a kit, however the rules have changed in europe so that many kits now also require EMC certification through a test lab as well. Kits are still exempt from EMC in the US and Aus (AFAIK at last look).If its not for sale ie just for yourself EMC is usually exempted.Remember its always easier to ask for forgiveness than permission.

author: David Aurora
author_rank: Frequent Contributor
timestamp: March 24, 2012, 03:18:10 am
content: No dice on iso transformers. I can't be bothered running through the discussion I had about them, but just trust me that when I said I discussed every option with them I meant it. I'm 99.999999999999999% sure there is no workaround here guys, hence the search for the chunky plug packs. If someone can give me a direct quote from the licensing authorities showing a suitable workaround that's fantastic, but short of that I can tell you with pretty good certainty that none of the obvious workarounds are going to pass here so I'd rather focus on the plug pack option.Yeah unfortunately that's the same conclusion I came to- it looks far easier to design something (though the prototyping is illegal if you wire up your own power supply from mains...), have it made overseas and import it back in. Ridiculous.The sales question is pretty much not right now, but one day that's the plan (though I do already sell some battery powered/9 volt wall wart type things). I'm mostly building stuff for myself at the moment, learning more and more about it all, but one day I'd like to be able to sell the bigger stuff. Which is why I got in contact with the licensing people in the first place, to ask what steps I need to take now to make that happen later. I shudder to think how far behind we'd be with technology right now if these laws had applied in the past.

author: gregariz
author_rank: Frequent Contributor
timestamp: March 24, 2012, 07:49:42 am
content: Your real problem is that Amplifiers are a consumer item.If you stick to plug packs (wall warts) you are free of electrical licensing as you know, so I think you are on the right track there. I bought a rather large 55 watt 18VAC 2.2Amp plug pack recently for a radio application that cost me less than $20 at Jameco. However it is a US only voltage. So I suspect they must be out there.Maybe something likehttp://www.jaycar.com.au/productView.asp?ID=MP3045&form=CAT2&SUBCATID=1000#12If you stick to designing test equipment, R&D equipment, unfinished products, boards and kits you are generally also exempt of EMC/FCC requirements. ie all of the kits, boards and modules you see people selling all over the net without any regulatory hurdles. If it were me, and I wanted to do a consumer item, as I said above I would probably do it in Asia.I'm digging into some long lost memory here but I thought that one way around plugging into the mains was to use an isolation transformer. Something like the followinghttp://www.flanagan.com.au/isolation.htmTechnically then you are not plugging into the mains. I wouldn't run the idea past the electrical board because their standard answer is no but my guess is that you wouldn't find anyone who could tell you that was legal or not - but at least if they did find out and crack a fat about it you could demonstrate that you had a good dig to do the right thing. Again, its easier to ask for forgiveness.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: March 24, 2012, 11:57:23 am
content: QuoteNo normal (i.e. not medical or other specialist areas) in Europe requires EMC certification by a test lab - manufacturers can self-certify that a product meets the requirements

author: nukie
author_rank: Frequent Contributor
timestamp: March 24, 2012, 02:29:51 pm
content: David Aurora - if you become a politician one day I will definitely root on ya.

author: harnon
author_rank: Regular Contributor
timestamp: March 24, 2012, 02:43:18 pm
content: Quote from: mikeselectricstuff on March 24, 2012, 11:57:23 amFrom my reading of the CE certification directives its one of those lovely legal situations where you aren't required to go to a lab but if you self-certify and then get audited, if you can't provide documentation to say you are compliant (e.g. lab test results) you'll get shafted.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: March 24, 2012, 03:51:30 pm
content: Quote from: harnon on March 24, 2012, 02:43:18 pmIn theory, but in practice the system is complaint driven, so you won't get ranomly checked (except possibly in Germany), and even then ISTR you have something like a couple of weeks to come up with documentation.

author: gregariz
author_rank: Frequent Contributor
timestamp: March 24, 2012, 07:16:23 pm
content: Quote from: mikeselectricstuff on March 24, 2012, 03:51:30 pmYes you are right, if I were a small business in europe the only way forward would be to try my best to produce some kind of self certification document. In the US the only people we really see getting actively pursued by the FCC are people selling intentional radiators (ie wireless devices). There's usually a regular list of ebay sellers on the FCC's database who have been fined or warned. As a general rule I doubt they care about much else unless they get a complaint.

author: gregariz
author_rank: Frequent Contributor
timestamp: March 26, 2012, 07:59:54 pm
content: I was just looking through my doc folder and I found this. Maybe it gives another perspective from that of a test lab. They would probably give you better advice than the electrical authoritiesEdit: I thought about this for some reason and something seems funny in the whole thing to me. Most of the arguments about this topic that have occured over the years have to do with whether electrical engineers should be able to do fixed wiring, ie change a socket in their house. (The result has always been no) I've never heard of the electrical authority shutting down an electronics manufacturing enterprise because they used a power transformer in a piece of consumer electronics. The reason that I would typically use a plug pack is not because of the electrical regulations not allowing me to wire it but because it relieves me of having to get product certification testing at a test lab which is very expensive. Australian manufacturers do use minimally trained people to do electrical wiring and assembly as long as they work to an instruction prepared by an engineer/competant persons. Queensland has always been a bit funny but they've gone to the extreme of restricting the changing of plugs and cords (IIRC) which all the other states allow the public to do.see the following exemptions for nsw (QLD is the same apart from the plugs and cords (Ithink?));http://www.legislation.nsw.gov.au/fragview/inforce/subordleg+674+2011+ch.4-pt.4.7-div.1-sec.146+0+N?tocnav=y

author: e100
author_rank: Frequent Contributor
timestamp: April 09, 2012, 01:54:33 am
content: Re-sell bench power supplies instead of plug packs, remove the voltage/current control knobs to stop people changing the settings and connect the suitably insulated low voltage outputs to your custom electronics.Market the thing as a two distinct products that are sold as a pair, one part 'certified mains safe', the other extra low voltage electronics.

author: mobbarley
author_rank: Regular Contributor
timestamp: April 09, 2012, 12:28:50 pm
content: how about series / parallel strings of plug packs.....