New DMX dimmer pack

**ukewarrior** · 05-29-2012, 06:21 PM

Yep, finding a transformer will be a trick. I tried and couldn't locate one.
Nuts.
Without a viable alternative, it makes the design unusable going forward and that would be a shame.

Originally Posted by james1095

I should add that the PCB mount XLR connectors are available from All Electronics http://www.allelectronics.com Cat# XLR-3FC and XLR-3MC. The power transformer is the only other potentially tricky bit. It's a standard current production part that I found on ebay. Digikey lists it but doesn't normally stock it. You can of course use any power transformer with similar specs, but a different one may not fit on the PCB.

**james1095** · 05-29-2012, 06:28 PM

Originally Posted by n1ist

Looks nice. One issue; on the mains connector, you have L and N reversed in the silkscreen.
/mike

Damn! I just checked and you're right, good catch! L should go to the fuses, N is the common bus along the back.

I'll fix this when I have a chance and upload a new set of files.

**james1095** · 05-29-2012, 06:38 PM

Originally Posted by ukewarrior

Yep, finding a transformer will be a trick. I tried and couldn't locate one.
Nuts.
Without a viable alternative, it makes the design unusable going forward and that would be a shame.

So modify the layout to use whatever transformer you like, KiCAD is open source so the tools are freely available.

Alternately, mount the transformer off-board in the case. There's nothing mandating that it be included on the board, I just did it that way because I wanted a very compact, monolithic design.

All you need is a single secondary (or two that can be paralleled) producing 6.6-12V at about 180mA. It does have to be a conventional iron (line frequency) transformer because the zero cross signal is derived from this.

The transformer I used is a DST2-12B42 made by Pulse. Digikey lists it but you have to buy 200. Mouser has them but the minimum there is 80 units. I did a bit of searching and found at least one cross reference available, but I haven't done much serious looking. I don't see this as an insurmountable obstacle, even if one can't be found, the hard work has already been done.

EDIT:
Here is one that claims to be a substitution:

http://premmagnetics.com/Products/Details/SPW-351-D

Double check the mechanical aspects prior to purchasing though to make sure it will fit.

**n1ist** · 05-29-2012, 06:45 PM

It looks like Pulse is getting out of the small power transformer business; RJ got burned by them on the Lynx SSR4DMX and splitter. The best I have found is 3FD-312, but that won't fit due to the DIP switch...

**james1095** · 05-29-2012, 06:50 PM

Originally Posted by n1ist

It looks like Pulse is getting out of the small power transformer business; RJ got burned by them on the Lynx SSR4DMX and splitter. The best I have found is 3FD-312, but that won't fit due to the DIP switch...

That could be why I got the tray of them cheaply on Ebay. I've made several different designs using them, when I need more I'll use something else. Being able to get small batches of PCBs ridiculously cheaply from Seeed makes it trivial to revise a layout to make use of whatever parts I can get.

Either way SPW-351-D looks like a drop in replacement that ought to clear the DIP, but I don't have KiCAD on this machine to double check. Space was tight since exceeding 10cm*10cm would have bumped me into a higher price bracket for the PCBs, but it made for a nice compact board with the parts I used.

**james1095** · 05-30-2012, 12:11 AM

I fixed the silkscreen error, flipped the rotation of the over-temp adjustment pot since it was technically reversed from what I had intended, and added a BOM. After a lot of 404 errors I managed to upload the new zip in the files section. Hopefully this clears up most remaining questions.

**ukewarrior** · 05-30-2012, 10:12 AM

By any chance did you confirm if this IS a drop in replacement or not?

Originally Posted by james1095

Either way SPW-351-D looks like a drop in replacement that ought to clear the DIP, but I don't have KiCAD on this machine to double check. Space was tight since exceeding 10cm*10cm would have bumped me into a higher price bracket for the PCBs, but it made for a nice compact board with the parts I used.

**ErnieHorning** · 05-30-2012, 12:28 PM

Prem's website lists the SPW-351-D as a replacement but I don't see anyone but Prem that has it.

The Triad Magnetics FS12-090 seems to match the Prem dimensions. Mouser part number 553-FS12-090.

**james1095** · 05-31-2012, 07:27 PM

Originally Posted by ErnieHorning

Prem's website lists the SPW-351-D as a replacement but I don't see anyone but Prem that has it.

The Triad Magnetics FS12-090 seems to match the Prem dimensions. Mouser part number 553-FS12-090.

Best way to tell is to study the datasheets and compare dimensions. As long as the pins line up there is some leeway with the length and width of the core. The space between the base and the bottom of the iron core is somewhat important though since the core hangs over the DIP switch. This still may be worked around by not inserting the pins all the way down into the board or locating a shallower DIP switch. Another thing worth mentioning is don't rely on the photos Mouser shows. Frequently they are a stock photo and may be another product in the series rather than the one you're actually ordering.

I'll help out where I can, but please remember that I designed this thing for myself around my own needs and the parts that I had. I'm providing the design for free so that anyone who wishes to duplicate it may do so, but to some degree you are on your own as far as locating suitable parts or altering the design to accommodate parts you can get.