Ok I jumped the gun a bit, the sinkpad samples arrived today. Great stuff!
I got 6xhp70 coppers, 1xhp70 alu and the rest a mix of copper and alu xhp50 stars.
—
First impressions:
I don’t like the tiny traces they used to accommodate the 6v/12v configuration on these stars. They’re really wimpy and even in the 6v config much longer than they should be.
As we’ll likely never need to run these LEDs at anything other than the 6v config in a flashlight, that makes these traces an unnecessary complication.
Shorting the LED pads out with copper strips soldered across and running 10Amps through in the 6v Config I measured a 0.124v drop across the traces!
That works out to a resistance of 0.0124Ohm, really not great. We wouldn’t touch a DD mosfet with that high of a resistance for example.
at 15A it’s 194mv
at 20A it’s 285mv (you know someone will run 20amps through one of these suckers soon enough! )
Based on this, I’d say stick with the MKR variant sinkpads (only 6v compatible) or wait for a 6v optimized noctigon with beefy traces.
This is off topic, but this is why even with the best of meters and short heavy gauge test leads, it is impossible to get accurate current reading of the draw on these high amp lights. Those meters use a 0.01 ohm shunt resistor. Much voltage is dropped across it and effecting greatly the actual current draw during the reading. These LEDs are greatly affected by that slight voltage drop and why I posted about that 0.001 ohm external current shunt.
Yes good point, standard multimeters really shouldn’t be used to measure high current accurately. Best thing you can do is measure current and output at the same time, then just output in the assembled light. If there are any differences in the measured output then that would show a false current reading.
I use a Turnigy 100A watt meter that has a 0.001ohm internal shunt and beefy 6mm bullet connectors but even then I still have to take it’s influence into account.
These are not punched on the back like the old sinkpads, so there is quite a cavity that needs to be filled with solder on the thermal pad.
It’s basically like when we scrape the dielectric layer off cheap copper pcbs and have a hole to fill underneath the emitter.
They claim there’s very little difference in performance but I think there’s more of a chance to mess up a reflow for us by not applying enough solder to fill the gap. I dunno if that’s really a problem in practice, but I don’t like it.
Has anyone considered using a piece of Cu foil to fill the divot instead of a pool of solder?
Also even easier would be to use 96% silver solder, that should be even better than Cu foil since there’s only two material transitions then (LED to silver solder, silver solder to Cu MCPCB). With a piece of Cu foil there would be four (led to solder, solder to Cu foil, foil to solder, solder to MCPCB). Even if you had the foil pressed against one of the two (LED or MCPCB) there would still be those 2 additional transitions. Seams like silver solder will be the best method for dealing with MCPCB’s manufactured like this (or cheap ones we scrape).
From looking at the recommended solder pads for XM vs XPH50 it looks like you could just use an XM Noctogon or SinkPad with a Zener mod driver for 6V use. I’m thinking of trying this out since I never loaded the XM pill for last years contest light due to lack of a potent enough 2-cell driver. Would love to get one in an F4.
I think it’s sintered. Looks smooth to the bare eye, unlike the base; although both feel smooth. The gap is quite big as in quite visible without magnification, not an optimal design. I don’t have any tools to measure its exact depth.
I don’t know what you mean by beam. If you mean the cutout, it seems like it’s a bit more shallow on the XHP50 version.
If you mean the +/- pad for the LED, this one is for XHP50 http://i.imgur.com/I1BhEaY.jpg and this one of the XPH70 variant http://i.imgur.com/Cmv8WdO.jpg.
I also received a few 70 and 50 sinkpads. But I think they are not that good, while reflowing the coating turns brown very fast even if you keep the temperature low. Also the coating starts to get little cracks and the + and - pads are very easy to pull off.
Not so impressed
agreed…I think the onesies and twosie freebies are ok…but hammering them by getting 10 at a time is uncool…maybe a “business level” freebie of 10 sure…but for individuals…sinkpad should limit their giveaways to 1-2 at a time.
It really does help getting samples…but 10 isn’t “sample” for some that is a full on order…I have maybe 15-20 sinkpads in my stock…I bought them…but wouldn’t need to if I just got em for “free”
I absolutely agree. Didn’t really think about it until Cereal_killer brought it up. That’s also why I think a giveaway on six of them would be “good karma”
I got mine in, and at least I made good use of one XHP70 board by redoing the integrating sphere XHP70 test (to be found in OL's XHP50/70 thread, post #575)
Can we give Sinkpad some credit and assume that they know how to run a business?
As far as I’m aware their minimum order quantity is something like 70 dollars. That says to me it doesn’t make financial sense for them to process any orders smaller than that, ie they’re more than likely losing money on small orders. Nothing unusual for large companies to do that, also not unusual for them to offer free samples to interested potential customers.
They’ve obviously felt it was appropriate to send out free samples (10) in order to get the new product out there and hopefully attract more business. I’m sure they’ve put aside a certain “marketing” budget and it will be up to them to call quits on the free sample offer.
Also, we may not be their primary customers. But getting their product into the hands of us enthusiasts (provided the product works as expected) can only have a positive knock on effect for the company as a whole. Since we may end up recommending the pcbs to others or ordering 5 or 10 or 20 more sinkpads from their resellers and so on.
Not to mention any mod carried out using these free samples and posted on a forum will have the Sinkpad branding plastered all over it. Essentially free web advertising.
-
I’m personally not that impressed with these pcbs so I think for me it hasn’t swayed me to buy any more. However that’s just the flip side of advertising a product and allowing the customer to try it out before they buy.
Ever taken a free test driver at a car dealership? I’m sure you didn’t feel you needed to have your karma adjusted after that right?
)
