Just got the Murata OKR T/10-W12 DC-DC converters delivered. They’re amazingly small for something that’s rated to deliver 50W! Only a tenner each, too.
Being small is a problem though: see those pins? 1.7mm pitch, not the standard 2.5mm (0.067in vs 0.1in). Very thick and stiff, not long enough to bend down 90° and poke through a board. They need a trim pot to set the voltage, so I need to mount them on a board—dead-bugging everything is a little too dodgy for me, especially with the currents involved.
For the life of me I can’t find any kind of socket or 1.7-to-2.5mm adapter.
Aside from soldering wires directly to the pins, has anyone got any ideas how I might mount these flat to veroboard?
Might be worth drawing up some little PCBs — it’s not too expensive and perhaps if you make a universal design as a breakout board others could use it too.
I’ve got one of those in my modular synth power supply.
Wow rated at 50W, cool. That looks great, minus the 1.7 pitch trickiness. For your build do you need to On/Off Control (pin 1)? If not, can you cut that off and perhaps spread the pins out enough for the veroboard?
Nuts, seems like there would be at least some sort of 1.7mm pitch plug out there. I’m not seeing anything either
You have to wire 16 of these, one in each light stick, right?
@marmil , yeah, 16 of the little buggers. I don’t need the on/off pin but that doesn’t help in any case—the leads aren’t long enough to bend down into the holes in perfboard anyway.
Desoldering the existing pins on 16 of these is a hell of a job and fraught with danger, I don’t want to go there.
You said you wanted to mount them flat to the board so vertical is out, but just for my own knowledge, do you think the pins are long enough that it /could/ mount vertically? (Assuming pin 1 cut off, could the remaining four pins bend/separate out enough go into veroboard?)
I’d take a standard 0.1" right angle male header and remove the gold pins from it. Solder them to this converter so that they are pointing down, but fanning out. And then with some pliers and patience, spread out and bend the new pins back to 0.1" pitch. Dunno if my description is clear, but hope it helps.
@marmil Maybe with judicious application of a Leatherman I could do that and only destroy about half of them in the attempt. Maybe. I’m literally a hack with this stuff.
@Anool_Mahidharia I understand where you’re going and think that’s the next best option to making a proper board. I’m currently asking around to see who might be able to mill me a board locally in Amsterdam; theoretically I have the time for OSH or similar to turn me around a board, in practice I have to get it right the first time which I doubt I will be able to.
@Giligain_I I came across those, but I don’t think they really help me, the “socket” on those mounts to a kind of blade receptacle (not pins). I literally can not work out what “real” EEs do with these things.
@Kasper_Kamperman The data sheet is here (http://power.murata.com/data/power/okr-t10-w12.pdf) but the renderings don’t really give you a sense of scale. I was quite surprised by how tiny they were when they arrived. Possibly the Mouser and Farnell pictures are older revisions? The pins don’t bend down far enough to put on a board, unfortunately.
Thanks for the help though guys—any further suggestions gratefully received!
@Robert_Atkins This morning I took a stab at making a breakout board for you. https://oshpark.com/shared_projects/nDspkFIv
I’m not exactly happy with it but I can’t afford to put anymore time into it. I thought maybe you could lay the pins flat onto smd pads routed to standard pin headers.
I made the traces as wide as I could and added vias to transfer some current to the back but I still wouldn’t feel comfortable pulling ten amps through it. The biggest problem I have with it however is that it’s twice the size of the converter which defeats the whole purpose. Anyway, hope it helps give you some ideas at least.
I had resigned myself to having to spend some serious hours with Eagle this weekend (never even touched it before) and just in a couple of sentences there you’ve clued me in to a bunch of things I never would have considered. My approach as you suggest was going to be to mount it SMD-style on the edge of the board, with the +ve input going through a fuse holder, and adding space for a trim pot, plus a 4-position screw terminal housing (Vin, 2x ground, Vout).
Will either OSH Park or Eagle warn me if I tell it the traces are too thin for the current I wish to draw?
Nope, but the smoke will. You can do the math yourself but a quick google of “trace width current” will give you some calculators. I was maybe a bit conservative with my estimates. The board as i made it might be able to handle 10 Amps but would “run a bit warm”. The pin headers are the other bottle neck. I allowed a max 3A/pin. So you’d want to check the rating on the screw terminal you plan to use.
The best I could find still is these, but not sure about current/voltage limits. Only SMT at that 1.7mm pitch too…no through holes.
CONVERT TO 5 PIN SIP ON .1 in. CENTERS http://www.capitaladvanced.com/33115.htm
Oh, cool. Someone had pointed me to a vague reference to those Surfboards before (electronics Stackexchange I think), but wherever it was they had no stock.
Because I need the trim pot, fuse and terminal block I think I’m going to have to go with a custom board for this one. Big step up for me
