kevin gilmore

goldenreference low voltage power supply

369 posts in this topic

Just a heads up that 7v reference and 1.07kOhm RN60 worked fined for 12V output. I powered it up and +11.98 and -12.00 dead steady on the board. Only need the +12 half for my purposes but I figured if I ever repurpose it later, it's easier to swap around a couple resistors than hunt down some transistors that might be OOP years from now.

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Posted (edited)

Got my spare parts GRLV PSU all finished up for the mini stax amps today. Wiring is a little ugly since I left the transformer leads long in case I ever want to repurpose the transformer again and left the other primary intact for 220V. Used an inline fuse because there wasn't really a good spot on the back panel that wouldn't look weird or collide with the board. The Kemet caps were nice and short enough for me to put in the case but since they're fat required adjusting some of the other bits before soldering to make sure they fit.

Had some decent little heatsinks on the pass transistors originally, but even though the amp only pulls about 300-400mA, they got way too hot too quick. The bottom plate worked fantastic though and once assembled, the whole chassis spreads heat to all parts pretty well. And I just noticed in the picture that I forgot to scrub all the flux off those when I remounted them. Well, better go fix that.

Hope you guys enjoy this particular combination of spare parts pile and overkill. Only cost me about $70 to put together with what I had laying around and half that was the case.

Hs76qfO.jpg

EJFMMtS.jpg

x7tdebV.jpg

YsUSVJ1.jpg

Edited by Tinkerer
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22 hours ago, Tinkerer said:

Got my spare parts GRLV PSU all finished up for the mini stax amps today. Wiring is a little ugly since I left the transformer leads long in case I ever want to repurpose the transformer again and left the other primary intact for 220V. Used an inline fuse because there wasn't really a good spot on the back panel that wouldn't look weird or collide with the board. The Kemet caps were nice and short enough for me to put in the case but since they're fat required adjusting some of the other bits before soldering to make sure they fit.

Had some decent little heatsinks on the pass transistors originally, but even though the amp only pulls about 300-400mA, they got way too hot too quick. The bottom plate worked fantastic though and once assembled, the whole chassis spreads heat to all parts pretty well. And I just noticed in the picture that I forgot to scrub all the flux off those when I remounted them. Well, better go fix that.

Hope you guys enjoy this particular combination of spare parts pile and overkill. Only cost me about $70 to put together with what I had laying around and half that was the case.

Hs76qfO.jpg

EJFMMtS.jpg

x7tdebV.jpg

YsUSVJ1.jpg

Nice.I would do this 12v version in the future too.Now i don´t even need to calculate the right value for the resistor .i will use yours ;)

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22 hours ago, Tinkerer said:

Got my spare parts GRLV PSU all finished up for the mini stax amps today. Wiring is a little ugly since I left the transformer leads long in case I ever want to repurpose the transformer again and left the other primary intact for 220V.

 

 

 

You didn't wire the primaries in parallel for 120V? I guess I've never heard of that being done (not that that means anything).

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1 hour ago, Pars said:

You didn't wire the primaries in parallel for 120V? I guess I've never heard of that being done (not that that means anything).

The toroid came from some other big amp. I bought it second hand awhile back. The setup for the primaries is weird. The 220 is a fully separate winding.

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On 4/27/2017 at 2:24 PM, Kerry said:

Here's a new layout I'm working on.  It's a GR HV/LV, Bias and Delay circuit (with LED flasher) all on one 4 layer board (3.5" x 5.5").  The pass devices can mount to the bottom plate or a heatsink.

Mostly SMD parts and uses the GR78/9xx modules.  Once tested I'll make this all available.

 

GRPS.jpg

GRPS-B.JPG

Got the boards back.  I should have this tested in the next week or two :)

IMG_0481.thumb.JPG.a0a103d5e81d911a3a951b07324a4503.JPG

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Cool! Man, you're like the energizer bunny with all these projects going on! Where do you find the time?

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Posted (edited)

Fedex came trough today. Got my first GRLV up and running. I think / hope the left multimeter is more accurate will replace the right one soon. With the small load, I did not burn trough the Fuse but I burned trough the first one. Was thinking a little bit too small one the fuse side I guess XD

20170511_223715 (Medium).jpg

Edited by masamoto

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Posted (edited)

^ Looks good. Interesting measurement technique with load from V+ to V-.

Mounting pass devices to heatsink

For the GRLV for my dynafet, I need to mount the pass devices to one of the heatsinks. Since I am using a modushop/hifi2000 3U pesante, the mounting rails for the heatsink are preventing me from getting the GRLV close or right up to the heatsink, and I think the distance is more than I care to bend the leads for the MJW21193/4s. Since the amp boards are drawing ~0.8A, I don't think that mounting these to the bottom panel is sufficient.

Should I:

  1. Go ahead and bend the leads
  2. Drill holes in the mounting rail to accommodate the standoffs and position the board close to the heatsink
  3. Shorten 2 of the standoffs by the thickness of the mounting rail so it can sit on top of it
  4. Remove the standoffs by the heatsink and let the output devices support that end of the board

I don't have any angle brackets wide enough for these devices, and there is not any provision on the PCBs for these anyhow.

Pics of how you have done it appreciated! I did look, but didn't find much with this case type problem.

 

Edited by Pars

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attach the pass transistors to short wires

its done a lot more often than you think on big expensive instruments

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Ah is there something I did wrong or is bad :unsure:

I also measured relative to ground as well.

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That had occurred to me Kevin, thanks! I might go with that.

masamoto: no, nothing wrong with that. I usually am more interested in relative to ground to see the balance between +/- though.

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I got the HV sections and bias up and they work perfectly :) 

Here's the board...

592cd4f19cbaf_FullSizeRender1.thumb.jpg.fd2d370d58ead9370258abb57b520f82.jpg592cd4f32c8f3_FullSizeRender2.thumb.jpg.0a97f7b357080c8fe74e10003c3e91de.jpgFullSizeRender.thumb.jpg.d6dba2defc64b5b80bdae8bd25a2be81.jpg

I've already tested the GRLV boards and they work.  I just have to build another set for this supply. 

The thermals above the IXCY10M90S regulators don't go above 99 deg. F.  Very happy with the board so far.

 

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Agree, very impressive. Can't be done much smaller.

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Got the LV supplies done now.  All good 😊 

IMG_0585.thumb.JPG.0353923b8907d0fce1d432285b300606.JPGIMG_0590.thumb.JPG.19a6a2e42b83d2de4954ec920416f86b.JPG

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Posted (edited)

An everything in one PS PCB with a footprint not much different than my iPhone 6 Plus. Incredible design and work Kerry! 

Edited by Laowei

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This is terrific work. I wonder if I have the SMT skills to stuff a board like that. 🙃

Could you explain the heat sinking story here? I always made sure to attach GRLV's MJW21194 and 93 to an external sink or at least the chassis. Doesn't seem like you're doing that here. Is the expected dissipation need really low? Same question about all devices needing a sink on the HV side. Run them to a sink with wires, as Kevin suggested?

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This supply is going into a carbon so the current draw is very low.  For a higher current use you should mount the LV supplies to a heat sink.

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