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from the what-will-they-think-of-next? dept.
Ras Pi foundation announces a new product: the compute module.
The compute module contains the guts of a Raspberry Pi (the BCM2835 processor and 512Mbyte of RAM) as well as a 4Gbyte eMMC Flash device (which is the equivalent of the SD card in the Pi). This is all integrated on to a small 67.6x30mm board which fits into a standard DDR2 SODIMM connector (the same type of connector as used for laptop memory). The Flash memory is connected directly to the processor on the board, but the remaining processor interfaces are available to the user via the connector pins.
While not yet what I imagined by only the name i.e a unit to build a shoebox-sized Beowolf cluster of 1K-RasPi-cores the new form factor and pin-out should make this endeavour easier (ahem... for someone skilled in PCB design, EE practician, and a soldering-fu master that has achieved enlightenment... not quite my profile).
(Score: 2) by anubi on Friday April 11 2014, @01:43AM
I can tell for sure you have been around the bush a few times! ;)
I have even used your heat gun trick to remove boardfuls of components at a time, with the exact result you reported: blown away. But I did get some SMD parts recovered to use on other things.
Love your warning about pin#1. Done that a couple of times myself. Sure made me mad when I realized what I had done wrong.
About the wide tip and bridging... that's what the rosin-soaked solder wick is for. The wick will absorb the excess solder so there isn't enough material left to make a bridge, but there will be ample left to wet the area between pin and pad. With my older iron, typically the end of the iron covers darned near a dozen pins. The solder itself is several pins wide. So I run my iron and wick along the part after I have soldered it down and its full of bridges ( sometimes a solid bridge ), using the wick to remove the bridges. The solder that wicked up between the pin and pad stays there. The remaining pins hold the part in place while I am wicking up the excess.
Thanks for the stencil link. I have really got to learn about how do do this.
You are so right about the drug store isopropyl.... I do not like to use the drug store stuff for the exact reason you stated... its got too much water in it. The best stuff I got was some stuff from the hardware store that was marked I believe as lacquer thinner and came in a gallon can.
As far as the China link to AliExpress: I have used them a few times and found them to be a decent supplier, albeit you have to watch your descriptions and shipping/pricing closely. My own findings were that buying consumer items was tricky, as my experience has shown I would have come out better just going to a retail store where I could personally inspect the thing before purchase. The expense of shipping often is more than the price of the item ( even if the merchant offers free shipping from China; if you get the item and it fails to meet your expectations, you are expected to return it at your expense. Fair enough I guess. Order a couple of samples and be prepared to just "eat it" if they are not what you thought.)
I have used their dispute arbitration system ( and in all cases I called on it, they ruled in my favor ), however I used it only as a last resort before calling on VISA to reverse the charges - also knowing I would forever be barred from any future transactions through Ali. So far, I have had pretty good experiences buying parts and assemblies such as Arduino compatibles, power converters, and LED assemblies. I have presently got an order with them for a lot of IRF510, which I intend to use in building another power supply for my METCAL. I have always wanted a small 12-volt soldering iron, and I was lucky enough to get a dozen handpieces for these at a surplus house ( the power supplies were all blown ). Being I have worked in RF a lot, to me these looked just like a 13.56 MHz CCFL ( cold-cathode fluorescent lamp ) driver to me. No biggie.
A little offtopic: I understand your reluctance to enable JavaScript. I have noted that it is darned near impossible for me to go to Amazon anymore, and I cannot help but think I am infected with something that interferes with Amazon, yet my own virus scanners tell me I am clean. I hardly ever buy from Amazon anymore, as I do not know whether or not Amazon just got a new script-crazy webmaster, or did I pick up something from China that is inhibiting Amazon. For me, the AliExpress site works, Alibris works, Amazon is slow as all getout and is apt to simply lock up at the oddest moment. I am running a WIN7 box with Firefox/NoScript.
"Prove all things; hold fast that which is good." [KJV: I Thessalonians 5:21]