flyfisher Posted June 12, 2012 Share Posted June 12, 2012 [quote name='BRANCINI' timestamp='1339496313' post='1689188'] I understand your point, but I think you'll find said sparkie is obliged to only use certified equipment. So dont forget to ask the insurance company and the fire officer if they are happy with you using a non CE certified power supply, built by the local sparkie, and connected to the mains, just so long as he puts a PAT label on it.... . For the sake of the cost of two 'Battery Eliminators' it just aint, imho, worth the risk. [/quote] Sadly, in these increasingly litigious days, those are very good points. DIY electronics is fine for personal use but once things become commercial then such complications can raise their ugly heads - especially when safety-critical components such as mains PSUs are involved. I wouldn;t think twice about building an effects pedal powered from 12v, but I'd still buy in the mains PSU to power it because it will have been tested and certified as meeting all the required safety regulations. I suppose it's technically possible to argue that a DIY PSU doesn't legally need to be CE-marked or certified for electrical safety (and EMC standards) because it's not being "placed on the market", but it's not an argument I'd like to have while combing through the smoking remains of my last gig venue. Also, because there's no real financial savings to be gained by DIYing a mains PSU and there's no significant technical or functional advantages either, I really can't see any practical reasons for not just buying a commercial PSU. Quote Link to comment Share on other sites More sharing options...
BILL POSTERS Posted June 12, 2012 Share Posted June 12, 2012 [quote name='flyfisher' timestamp='1339497407' post='1689209'] Sadly, in these increasingly litigious days, those are very good points. DIY electronics is fine for personal use but once things become commercial then such complications can raise their ugly heads - especially when safety-critical components such as mains PSUs are involved. I wouldn;t think twice about building an effects pedal powered from 12v, but I'd still buy in the mains PSU to power it because it will have been tested and certified as meeting all the required safety regulations. I suppose it's technically possible to argue that a DIY PSU doesn't legally need to be CE-marked or certified for electrical safety (and EMC standards) because it's not being "placed on the market", but it's not an argument I'd like to have while combing through the smoking remains of my last gig venue. Also, because there's no real financial savings to be gained by DIYing a mains PSU and there's no significant technical or functional advantages either, I really can't see any practical reasons for not just buying a commercial PSU. [/quote] Flyfisher - The voice of reason. Thanks very much, nice to see somebody else living in the real world. Quote Link to comment Share on other sites More sharing options...
daflewis Posted June 12, 2012 Author Share Posted June 12, 2012 (edited) [quote name='daflewis' timestamp='1339496870' post='1689195'] It's kind of gone full circle - I'd been hoping to find a way to power them from one psu (or at least one psu each) but it looks like that's just not feasible... [/quote] Why do people have to get so self-righteous - I was simply exploring all the options! Edited June 12, 2012 by daflewis Quote Link to comment Share on other sites More sharing options...
BassBod Posted June 12, 2012 Share Posted June 12, 2012 (edited) Daf - there is a Talk*ass post that recently showed how to do this with a Raven Labs unit - but I'm too stupid to do the link. It was using two outputs from a T Rex Fuel Tank power supply and a "custom" cable to provide the mini jack connection. Have a read..then show it to your theatre tech? [attachment=110255:PMBPScable.jpg] Edited June 12, 2012 by BassBod Quote Link to comment Share on other sites More sharing options...
LukeFRC Posted June 12, 2012 Share Posted June 12, 2012 [quote name='daflewis' timestamp='1339489604' post='1689044'] Hi Luke, Who? - please excuse my ignorance... Is he like OBBM for cables? - I'll check out some of his posts... Thanks for that, Daf [/quote] http://www.sfxsound.co.uk/ He knows his stuff and is a nice guy, send him a PM maybe? Quote Link to comment Share on other sites More sharing options...
daflewis Posted June 12, 2012 Author Share Posted June 12, 2012 Hi Bassbod, Thanks for that - it looks very doable (I'm sure I can find the thread) will definitely check it out! Luke, yeh, I searched members for him after your post and his stuff looks really well made! Though, as has been mentioned, an off the shelf supply is probably a safer and cheaper bet... But thanks anyway - it's good to have another option (and I'll certainly try him if I need anything custom making) thanks for that Quote Link to comment Share on other sites More sharing options...
BassBod Posted June 13, 2012 Share Posted June 13, 2012 Keep us updated? I've got a RL DI box, and am probably acquiring a red blender box soon, so I've got a keen interest in how this works out. Funny thing is, from what I remember from that Talkbass post, even though it works fine, the original poster still seems pretty unsure of exactly why it works?? I've always used batteries with my DI - they last a long time and I don't use it too often. But from what I've read, the issue with the RL stuff is really the mini jack plug connection - that can short out the supply quite easily if its connected/pulled with the power on. Quote Link to comment Share on other sites More sharing options...
daflewis Posted June 13, 2012 Author Share Posted June 13, 2012 Will do... It's very good to know about the mini jack shorting! Doesn't seem very good design given how good the raven labs stuff is in general... It makes me think that powering it through the battery connectors is the best option - I've already made some wooden blanks the same size as 9v batteries to keep the connector in place and i've cut a small notch out of the face of the battery boxes for the leads - this has worked well, so if the power supply you mentioned is suitable it may be i'm/we're in business! (especially if I can run the 2 units from that 1 supply) I'll get in touch with the company and check it out. Cheers! Daf Quote Link to comment Share on other sites More sharing options...
flyfisher Posted June 13, 2012 Share Posted June 13, 2012 [quote name='BassBod' timestamp='1339581863' post='1690807'] But from what I've read, the issue with the RL stuff is really the mini jack plug connection - that can short out the supply quite easily if its connected/pulled with the power on. [/quote] Yes, it's certainly not an ideal power connector for this very reason. It can be protected against, of course, by the PSU design but it then complicates things for 3rd party PSUs so I can't really see the point. Thing is, the lack of any real standards for low voltage DC power is a real pain for equipment manufacturers. In this case, there are plenty of 3-pin alternative connectors but you can never guarantee they're not also used by something else - e.g. an XLR would do a good job for a 9-0-9 PSU but someone, somewhere, sometime will end up plugging the it into a mic input! The PC industry has done a pretty good job with all their various connectors and it's pretty much impossible to connect things in the wrong way, especially with the colour coding of audio jacks, but I guess the music business has a longer history. Quote Link to comment Share on other sites More sharing options...
Silent Fly Posted June 13, 2012 Share Posted June 13, 2012 I am pretty sure the two batteries are used to generate +9V and -9V power rails. There are a few ways to address the problem: 1. Use two power supply units. This post explains how to do it: http://forum.allaboutcircuits.com/showpost.php?p=389259&postcount=13 I would probably reverse the blue and green wire instead of reversing the polarity of the PSU connector but it should work either way. 2. It should be possible use a 18V power supply adaptor and split the voltage using two resistors and a couple of capacitors. It depends how much current the MDB-1 uses but it should work. 3. Build a small unit that generates -9V from +9V. The unit would have a standard Boss-type power input and a +9V/-9V/GND output. Regardless the solution, it is very important to double-check the polarity of the connections and the type of connection on the MDB-1 uses as any reverse voltage may (and probably will) damage the MDB-1. Quote Link to comment Share on other sites More sharing options...
BassBod Posted June 13, 2012 Share Posted June 13, 2012 Well, I like option 3....but with battery clips for connection, rather than the mini jack??? Quote Link to comment Share on other sites More sharing options...
flyfisher Posted June 13, 2012 Share Posted June 13, 2012 Interesting device here: http://www.dimensionengineering.com/datasheets/Negatron.pdf It will operate with +9v in and can be adjusted to give -9v out at a maximum of 290mA. Would still need a small box and suitable cables but no safety-critical mains voltages to deal with. Loads of similar devices/circuits out there, so plenty of choice. (I'd still go for two PSUs though, for sheer simplicity and ease of carrying a spare). Quote Link to comment Share on other sites More sharing options...
daflewis Posted June 13, 2012 Author Share Posted June 13, 2012 Hi flyfisher, Good point! Actually I am a little surprised that the raven labs can't be phantom powered through the xlr send on the back anyway. Quote Link to comment Share on other sites More sharing options...
BILL POSTERS Posted June 13, 2012 Share Posted June 13, 2012 (edited) An option that hasnt been mentioned yet as far as I can see is a DC-DC Converter. This one would need a 12V supply, But there are probably others if you look for them, and as long as you use a certified 12V supply all should be well and it wont break the bank. [size=4][url="http://uk.farnell.com/xp-power/jah0212d09/dc-dc-converter-2w-dual-9v-o-p/dp/1859077"][u][color=#0000ff][color=#0000ff]http://uk.farnell.com/xp-power/jah0212d09/dc-dc-converter-2w-dual-9v-o-p/dp/1859077[/color][/color][/u][/url][/size] Edited June 13, 2012 by BRANCINI Quote Link to comment Share on other sites More sharing options...
daflewis Posted June 13, 2012 Author Share Posted June 13, 2012 Oops! Sorry, got a few posts behind there! Quote Link to comment Share on other sites More sharing options...
daflewis Posted June 13, 2012 Author Share Posted June 13, 2012 A dc/dc converter - would that kind of do option 3 that silent fly was talking about? Quote Link to comment Share on other sites More sharing options...
BassBod Posted June 13, 2012 Share Posted June 13, 2012 I can understand why the RL units don't use phantom power - this was explained to me by a fantastic tech a few years ago, something like the (up to 48v) voltage of phantom looks fine, but the amps (i.e. power) are very limited. The phantom system was intended to charge condenser mic diaphragms, and nothing else really. The DI boxes that run from it often have "clever ways" of working off limited juice...I don't think Steve Rabe was interested in that approach, he wanted clean headroom and quiet circuits. Having said that, my trusty Sansamp has run off phantom for years without ever behaving badly, although its always got a battery in it as well, and I've never run a high level (line) signal into it. Quote Link to comment Share on other sites More sharing options...
daflewis Posted June 13, 2012 Author Share Posted June 13, 2012 Ah, fair enough... Actually, on the subject of phantom power, that was another reason for wanting a power supply - the blender offers phantom power (perfect for my golden bullet mic) but that drains the batteries even faster! Quote Link to comment Share on other sites More sharing options...
BILL POSTERS Posted June 13, 2012 Share Posted June 13, 2012 [quote name='daflewis' timestamp='1339599925' post='1691255'] A dc/dc converter - would that kind of do option 3 that silent fly was talking about? [/quote] Not quite, you put 12V in and get two seperate 9V supplies out. All for under a tenner. But you'd need wire it to two PP3 battery clips etc. and put it in a box. Quote Link to comment Share on other sites More sharing options...
daflewis Posted June 13, 2012 Author Share Posted June 13, 2012 Sounds like that would work well... Oh dear, too much choice now!! Quote Link to comment Share on other sites More sharing options...
BILL POSTERS Posted June 14, 2012 Share Posted June 14, 2012 Two PP3 eliminators is still by far the simplest isnt it ? Quote Link to comment Share on other sites More sharing options...
daflewis Posted June 14, 2012 Author Share Posted June 14, 2012 Yes, it certainly is - so what would be perfect is if i could find a "multi" supply that has a floating ground so i could power both units (4 battery clips) from one plug - though from what has been mentioned it probably doesn't work like that... (though i will ask t-rex about theirs) Quote Link to comment Share on other sites More sharing options...
BILL POSTERS Posted June 14, 2012 Share Posted June 14, 2012 [quote name='daflewis' timestamp='1339688134' post='1692760'] Yes, it certainly is - so what would be perfect is if i could find a "multi" supply that has a floating ground so i could power both units (4 battery clips) from one plug - though from what has been mentioned it probably doesn't work like that... (though i will ask t-rex about theirs) [/quote] ........ [attachment=110400:gsmmains_adapt_large-500x500.jpg] Quote Link to comment Share on other sites More sharing options...
daflewis Posted June 14, 2012 Author Share Posted June 14, 2012 oh, very funny! Quote Link to comment Share on other sites More sharing options...
flyfisher Posted June 14, 2012 Share Posted June 14, 2012 Funny, but not so daft. Some of the multi-output PSUs I've seen would take up about the same space! Get a 4-way power strip, plug in four PP3 battery eliminators and put the whole lot in a suitable box. Spray it a nice colour, add some fancy blue LEDs and Bob's your Dad's Brother. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.