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Uncle Krunkus
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Joined: Jul 11, 2005 Posts: 4761 Location: Sydney, Australia
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Posted: Tue Sep 23, 2008 3:06 am Post subject:
Precision +/-15V @ 1A PSU Subject description: What I'd like to know is,...... |
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I'm working on a new precision +/-15V @ 1A PSU and I thought I'd share some pics and info on the process.
It's based on the LM723 (*2) regulator chip with MJE3055 transistors to carry the current load.
The schematic is freely available on the Elby Designs site. Here
I've done a stripboard layout of my own which I'll post if anyone is interested.
Please Note:
This DIY project involves the wiring of a mains transformer and associated IEC socket, fuse and switch. Attempting this without the proper precautions can be lethal!
If you have any doubts about your ability with mains potential wiring,... Do Not Attempt this Project.
No responsibility will be taken by myself or electro-music.com for anyone's ability or lack thereof to attempt a project of this nature.
I'll be posting some pics soon. _________________ What makes a space ours, is what we put there, and what we do there. Last edited by Uncle Krunkus on Fri Oct 10, 2008 4:28 am; edited 1 time in total |
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etaoin
Joined: Jun 30, 2005 Posts: 761 Location: Utrecht, NL
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Posted: Tue Sep 23, 2008 5:42 am Post subject:
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Thanks for reminding me of that one.
How easy would it be to pull out more amps? The MJE3055 can handle up to 10A so I guess the design is limiting in other places. I have some 2N3055 lying around that can do even more current. _________________ http://www.casia.org/modular/ |
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fonik
Joined: Jun 07, 2006 Posts: 3950 Location: Germany
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Posted: Tue Sep 23, 2008 7:03 am Post subject:
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the limitation is obviously the heat dissipation. take a look at these gorgeous heatsinks!
i thought about a 1.5A PSU using the units case itself as heatsink. thoughts? _________________
cheers,
matthias
____________
Big Boss at fonitronik
Tech Buddy at Random*Source |
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frijitz
Joined: May 04, 2007 Posts: 1734 Location: NM USA
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Posted: Tue Sep 23, 2008 7:57 am Post subject:
Re: Precision +/-15V @ 1A PSU Subject description: Build and Pics |
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Uncle Krunkus wrote: | I'm working on a new precision +/-15V @ 1A PSU and I thought I'd share some pics and info on the process.
It's based on the LM723 (*2) regulator chip with MJE3055 transistors to carry the current load. |
Interesting! How much better is this design than the LM317/LM337 regulator approach?
Ian |
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Peake
Joined: Jun 29, 2007 Posts: 1113 Location: Loss Angeles
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Posted: Tue Sep 23, 2008 9:11 am Post subject:
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fonik wrote: | i thought about a 1.5A PSU using the units case itself as heatsink. thoughts? |
So long as the case doesn't flex at all, know that it's been done (with extra dissipation hardware). The Prophet 5 comes to mind, but that's where I saw the problem- the regulator ICs were bolted to the case, and the length of the case allowed for flexing- and the leads eventually break off at the PCB.
My knowing "it's been done" doesn't mean that it was totally successful. You'd have to look into any tales of the reliability of the P5 power supply to confirm. _________________ We are selling emotions, there are no emotions in a grid. -mwagener
"IC 741. Sometimes you don't want fidelity." -Small Bear Electronics Catalog |
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bugbrand
Joined: Nov 27, 2005 Posts: 846 Location: Bristol, UK
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Uncle Krunkus
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Joined: Jul 11, 2005 Posts: 4761 Location: Sydney, Australia
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Posted: Tue Sep 23, 2008 2:59 pm Post subject:
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I was going to elaborate on that.
This design will actually allow me to up the Amps later.
I'm putting in an 18-0-18 @ 4A4 per rail transformer.
Initially I'll use the 1A per rail circuit, but I'm also looking at a way of beefing up that circuit using a TIP29 and a 2N3055 on each rail. And yes, the trick is to fit the right heatsinking in. It should end up being able to deal with about 3A per rail.
Right from the start, I'm putting it all in a 2U rack case, and designing the layout with the upgrade in mind.
That's why I thought you guys might be interested. _________________ What makes a space ours, is what we put there, and what we do there. |
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Sine
Joined: Sep 10, 2007 Posts: 111 Location: Netherlands
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Posted: Tue Sep 23, 2008 4:20 pm Post subject:
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I have built this thing and it is really rock solid with minimal drift
The only change I made is using darlington transistors so the 723 doesn't have to supply as much base current, something like the TIP140 or BDV65 would do nicely, or a MJ3001 if you must have a TO-3 in there |
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Uncle Krunkus
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Joined: Jul 11, 2005 Posts: 4761 Location: Sydney, Australia
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Posted: Tue Sep 23, 2008 4:24 pm Post subject:
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That's one of the reasons for going with the TIP29/2N3055. I'm going to do them as a discrete darlington pair. _________________ What makes a space ours, is what we put there, and what we do there. |
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Uncle Krunkus
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Joined: Jul 11, 2005 Posts: 4761 Location: Sydney, Australia
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Uncle Krunkus
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Joined: Jul 11, 2005 Posts: 4761 Location: Sydney, Australia
Audio files: 52
G2 patch files: 1
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Uncle Krunkus
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Joined: Jul 11, 2005 Posts: 4761 Location: Sydney, Australia
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Posted: Sat Sep 27, 2008 5:46 am Post subject:
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Two shots of the power socket and fuse holder. Note the lug for attaching the chassis earth. Check with a meter that there is 0R from the lug to the other end of the panel.
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_________________ What makes a space ours, is what we put there, and what we do there. |
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fluxmonkey
Joined: Jun 24, 2005 Posts: 708 Location: cleve
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Posted: Sat Sep 27, 2008 7:34 am Post subject:
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i cant tell from the pics what kind of ventilation scheme you're using? big heatsinks help conduct the heat away from the regulators, but it's still got to have someplace to go... vent holes and/or forced air. _________________ www.fluxmonkey.com |
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Sine
Joined: Sep 10, 2007 Posts: 111 Location: Netherlands
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Posted: Sat Sep 27, 2008 7:49 am Post subject:
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Great work on the case Krunkus,
Yes, a step drill is a MUST for anyone that does diy electronics.
I build mine on matrix board
Originally for +-12V, but later modules needed +-15V so I did a "upgrade" on it a few months later |
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Uncle Krunkus
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Joined: Jul 11, 2005 Posts: 4761 Location: Sydney, Australia
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Posted: Sat Sep 27, 2008 7:58 am Post subject:
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bbob wrote: | i cant tell from the pics what kind of ventilation scheme you're using? big heatsinks help conduct the heat away from the regulators, but it's still got to have someplace to go... vent holes and/or forced air. |
I'm not putting any ventilation holes at this stage, as this board is just 1Amp per rail. The 3A version (when it goes in) will have larger heatsinks and holes top and bottom. I'll sort out where to best place the holes once I have the larger heatsinks in place. _________________ What makes a space ours, is what we put there, and what we do there. |
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Uncle Krunkus
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Joined: Jul 11, 2005 Posts: 4761 Location: Sydney, Australia
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Posted: Sat Sep 27, 2008 8:03 am Post subject:
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I don't want to cut holes at the moment, 'cos I don't know where the larger heatsinks will be mounted. I've never built a PSU this size before, so I want to do a bit of testing under load and find out just how hot it gets. _________________ What makes a space ours, is what we put there, and what we do there. |
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Sine
Joined: Sep 10, 2007 Posts: 111 Location: Netherlands
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Posted: Sat Sep 27, 2008 8:13 am Post subject:
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Personally I would ( and I have on my version ) mount the heatsinks on the back of the unit. |
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Uncle Krunkus
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Joined: Jul 11, 2005 Posts: 4761 Location: Sydney, Australia
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Posted: Sat Sep 27, 2008 5:44 pm Post subject:
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Here's the distribution board.
I used stripboard, as I'm going with the .1" pitch molex style keyed headers and plugs.
The screw terminals are reverse mounted, and jumpered over with a piece of .7mm tinned solid copper wire. I continued this along the stripboard to maintain the cross section and keep the resistance as low as possible. I thought about adding an extra 2 caps at the other end of the distribution board, but decided that would be overkill and would just up the inrush current. What do you guys think? I could still add them later if needed.
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_________________ What makes a space ours, is what we put there, and what we do there. |
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Uncle Krunkus
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Joined: Jul 11, 2005 Posts: 4761 Location: Sydney, Australia
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Posted: Sat Sep 27, 2008 5:48 pm Post subject:
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Then I mounted it in the slot with 6mm threaded plastic spacers. These are great, as they eliminate the "now, just hold on to those 5 things while I get this one in place,....doh!" effect.
8 mounting points might seem a bit much, but it wasn't much harder than 4, and it means the board won't flex at all when connecting/disconnecting plugs.
I also kept it to one half of the panel depth, so I can add a second one later if need be.
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_________________ What makes a space ours, is what we put there, and what we do there. |
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blue hell
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Joined: Apr 03, 2004 Posts: 24075 Location: The Netherlands, Enschede
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Posted: Sat Sep 27, 2008 6:22 pm Post subject:
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Uncle Krunkus wrote: | 8 mounting points might seem a bit much |
When you'd space them differently you could use less ... irregular placement is better than regular and having them at the end of the board is not the best position re. flex reduction .. funny thing is that it's really a musical problem of sorts, the eigen frequencies of the mounted board should be optimized for max stability at least cost sorry, good morning is what I really meant to say _________________ Jan
also .. could someone please turn down the thermostat a bit.
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Uncle Krunkus
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Joined: Jul 11, 2005 Posts: 4761 Location: Sydney, Australia
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Posted: Sat Sep 27, 2008 7:54 pm Post subject:
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Blue Hell wrote: | When you'd space them differently you could use less ... irregular placement is better than regular and having them at the end of the board is not the best position re. flex reduction .. funny thing is that it's really a musical problem of sorts, the eigen frequencies of the mounted board should be optimized for max stability at least cost sorry, good morning is what I really meant to say |
Yeah, didn't you notice the gap in the middle is bigger? _________________ What makes a space ours, is what we put there, and what we do there. |
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bugbrand
Joined: Nov 27, 2005 Posts: 846 Location: Bristol, UK
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Uncle Krunkus
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Joined: Jul 11, 2005 Posts: 4761 Location: Sydney, Australia
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Posted: Sun Sep 28, 2008 6:03 am Post subject:
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bugbrand wrote: | Uncle K -- good work on the rectangular holes --- nice and tidy!! |
Yeah, that nibbling tool is one of the handiest things I've ever bought. Even more vital than a step drill IMHO. You hardly need to clean up the edges either, you can come right up to a line within less than .25mm. It does prefer aluminium to steel though, which is to be expected, but on a nice quality rack enclosure like this one, the front and back are aluminium which makes it easy. _________________ What makes a space ours, is what we put there, and what we do there. |
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Luka
Joined: Jun 29, 2007 Posts: 1003 Location: Melb.
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Uncle Krunkus
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Joined: Jul 11, 2005 Posts: 4761 Location: Sydney, Australia
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Posted: Wed Oct 01, 2008 6:02 pm Post subject:
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Yeah,
Hold on, I'll just tidy it up a bit. _________________ What makes a space ours, is what we put there, and what we do there. |
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