Shunt Regulated Salas Hotrodded DCB1 Build

[jls001]

The layout for magma's DCB1:

 

[keith_correa]

In Magma's DCB layout, wouldn't it be better if the positions of the transformer and PS board were interchanged? Wouldn't that result in a shorter path for the DC to the main board?

 

[omishra]

In Magma's DCB layout, wouldn't it be better if the positions of the transformer and PS board were interchanged? Wouldn't that result in a shorter path for the DC to the main board?

Yes, agree.

But here r-core within vicinity of no gain circuit may not make any effect.

 

[jls001]

The DC leads are barely 6-8 inches long from OPS board to DCB1. I can use thicker gauge silver-coated copper if that helps reduce potential losses across this distance.

Edit: on second thought, inserting a larger lead into the holes in the DCB1 board is not possible unless one substracts some of the strands (and defeating whatever advantage the larger lead may provide). Of course one can solder the lead onto the board without inserting into the lead hole. Looks a bit untidy, but I have done it when adding power rail caps.

Edit 2: if the holes for mounting the R-Core and OPS board have not been already drilled, swapping their positions makes sense. I guess the present layout follows the usual practice of having the transformer closest to the IEC socket (though I admit there's no real advantage).

 

[omishra]

The DC leads are barely 6-8 inches long from OPS board to DCB1. I can use thicker gauge silver-coated copper if that helps reduce potential losses across this distance.

It does not make sense to me. it okay, if you put twisted wires.

Edit: on second thought, inserting a larger lead into the holes in the DCB1 board is not possible unless one substracts some of the strands (and defeating whatever advantage the larger lead may provide). Of course one can solder the lead onto the board without inserting into the lead hole. Looks a bit untidy, but I have done it when adding power rail caps.

Anyway, on larger holes, solder pads on copper plain have heat spreaders around it. Its minute gap with surroundings connected with smaller tracks. So observe they have always finite contact with surrounding and thus in any return path of current.

Edit 2: if the holes for mounting the R-Core and OPS board have not been already drilled, swapping their positions makes sense. I guess the present layout follows the usual practice of having the transformer closest to the IEC socket (though I admit there's no real advantage).

I am not happy with these "EMD" r-cores. They are not true to theoretical R-Core. Ideally they should be build like - primary and secondary on separate bobbin around core. But EMD guys are dividing primary and secondaries on both bobbins, overlapping them. So its another step brother of toroidal. . Need to take this with them.

 

[jls001]

I am not happy with these "EMD" r-cores. They are not true to theoretical R-Core. Ideally they should be build like - primary and secondary on separate bobbin around core. But EMD guys are dividing primary and secondaries on both bobbins, overlapping them. So its another step brother of toroidal. . Need to take this with them.

Do you have any pictures or links? I can ask my usual transformer guy if he has such separated bobbins. He can probably source it or already have it.

BTW, the 130VA toroidal transformer I received from Jaibir as giveaway has two primaries:

PRI 1 Blue-White 0-120V
PRI 2 Violet-Grey 0-120V
SEC 1 Black-Red 0-15V
SEC 2 Yellow-Orange 0-15V

Brand is "Miracle". Product Code is M - 16030.

I am confused about the primary part since Indian primary is 230V. How do I connect the primaries? I am guessing I need to connect the two primaries in series to make it 0-240V. Is this how it must be done? Please advise.

The 120 VA toroidal I ordered for Rikhav's Salas DCB1 build is a simple 0-230V pri and 15-0-15V sec.

 

[captrajesh]

I am not happy with these "EMD" r-cores. They are not true to theoretical R-Core. Ideally they should be build like - primary and secondary on separate bobbin around core. But EMD guys are dividing primary and secondaries on both bobbins, overlapping them.

Oh!! That is bad news. Even FM Hydrovac has mentioned that their transformers are not up to the mark. Is there any other alternative source where we could get the R Cores made?

 

[omishra]

I am not telling about material. They have good quality core and bobbin. But while winding - primary winding must be finished on one, secondary must be finished on another one. But what I am looking is primary wire is coming from both bobbins, expecting it from only one. Same thing for secondary. So method of winding is wrong which must not overlap primary and secondary.

 

[anilva]

Joshua, finally what happened to your Salas DCB1?

 

[jls001]

Joshua, finally what happened to your Salas DCB1?

Hehe

Still a work in progress.

 

[doors666]

Whats the logic behind using a 200v 20a fet for a load that needs less than 10v and 10ma.

 

[doors666]

Oops, my mistake, didn't realize it was the part of the psu, just saw the schematic for this project.

 

[jls001]

What started in Sep 2014 finally saw completion

This build is for Rikhav.

All wired up and ready to be fired up for the first time:

Glowing:

Rear Panel: the cabinet fabricator misread my drawing and flipped the power socket and the signal connections. The front panel was correctly made, so the buffer ended up having a very long signal cabling to make up for the mistake.

Front fascia: 8 mm thick acrylic

I will request Rikhav to give his listening impressions once he's logged some hours.

 

[rikhav]

Not sure if it is the parts selection, the shunt supply or the hot rodding but the Initial impression are very good. Extremely good

Let me do atleast 20 hours

Thanks again to Joshua to help me build it. On the outside it looks a simple build. But I sat through with johsua when he was fixing the heatsinks and soldering wires at tight places

This sure is not easy.

Assembling the board is one thing and designing the cabinet another

 

[omishra]

Nice build, congratulations.
But i am confused with pictures of toroidal transformer fitting. Rubber pad must be at bottom over which transformer rests and metal washer at top with curved shape inside. None of the picture showing this correctly.

 

[jls001]

@Om: bottom of transformer has 2 layers of soft rubber so I utilized the one meant for bottom at the top

 

[omishra]

@Om: bottom of transformer has 2 layers of soft rubber so I utilized the one meant for bottom at the top

Thanks for the information.
Still last but one, picture showing metal plate upside down.

 

[jls001]

Thanks for the information.
Still last but one, picture showing metal plate upside down.

With the round indentation facing up it's actually easier to tighten the nuts I have been following the conventional way and have the indentation facing down but I find spanner reaches more easily when put upside down. Luckily I have sufficient height inside to play around.

 

[omishra]

Actually you are pressing winding at one circular path. Otherwise if indentation is inside then winding is pressed from inside out. Anyway your choice.

See this image -Tortran - High Efficiency Toroidal Electrical Transformer Design Guide - Bridgeport Magnetics Group

 

[prasen_b]

This is timely. Have been waiting for this build to be complete for quite some time. I already have a DCB1 using kit from sachin/omishra. Was wondering if a salas hypnotize will be better than the existing DCB1 + shunt regulated supply.