Mil spec electrolytic capacitors

Trying to figure out how to specify the caps that are in the parts drawer. They are clearly mil spec. MFR on the cases are Kemet, sometimes Sprague. Other numbers from the cases don't match any searches. One has a milspec part number M390006 on it.

What I have learned is:

Vishay does sell the M390006 ones:
http://www.vishay.com/docs/40022/40022.pdf

Sprague is now a subsidiary of Vishay. They sell caps very similar looking to the mil spec ones as series 150D which are "Hermetically Sealed" Tantalums. The datasheet says "The Military equivalent to the 150D is the CSR13 which is qualified to MIL-C-39003/01" The 150 series is available plentifully.

http://www.vishay.com/docs/40015/150d.pdf

CSR13 doesn't come up on many searches, and is apparently obsolete. However, I did find a Kemet datasheet which explains the numbering very clearly

http://www.kemet.com/kemet/web/homepage/kechome.nsf/file/Tantalum%20Hermetically%20Sealed-Axial%20Catalog/$file/F3100_TaHermSeal.pdf

Furthermore, after the first page of the above, there is an explanation of Kemet's newer numbering system, which is byzantine but the parts are available plentifully.

The difference between the M390003 and the M390006 is that the former is a solid tantalum, the latter a wet tantalum, as explained on the below surpluser's page. It appears that I have a bunch of the solid ones.

http://www.smcelectronics.com/milcap.htm

ERROR (LM-20): user/host/display not on option INCLUDE list for feature "Capture" ().

Trying to debug what happened to my OrCAD license yet again.

Google searching on the above error message, directed me to this page which does a damn fine job describing the INCLUDE list and other options file parameters:

http://www.ansys.com/products/icemcfd-tech-notes/flexuser/chap5.htm

Further digging shows that this file is just my license.dat file under C:\flexlm

Naturally, there is no "Capture" feature listed because our OrCAD is a site license. There's a bunch of Actel software features listed though, and I bet that when I installed those I somehow messed up the pointer to the OrCAD license server

iphone keyboard

Here is my first google search:

http://www.google.com/search?hl=en&source=hp&q=keyboard+for+iphone+bluetooth&aq=f&aqi=&aql=&oq=&gs_rfai=

The keyboard described in this breathless article seems not to have arrived, but one can always hope for the future.

http://www.appletell.com/apple/comment/a-bluetooth-keyboard-for-the-iphone/

The bottom line is that you have to "jailbreak" the phone to install a keyboard app, Apple will not allow installation of the bluetooth layers for keyboard interfacing. Here is a google search on the most popular hack:

http://www.google.com/search?hl=en&q=keyboard+for+iphone+bluetooth+BTStack&aq=f&aqi=&aql=&oq=&gs_rfai=

Here is a painstaking tutorial on how to download and install the hack:

http://www.iphonehacks.com/2010/01/how-to-use-a-bluetooth-keyboard-with-your-iphone.html

Scale factor

You wouldn't think this would be so hard. From now on, I'll just remember the cicadas in the following link:

http://www.learner.org/courses/learningmath/measurement/session2/part_b/

Also, this treatise was so well written that even if it didn't answer my question there's a lot to learn from it:

http://www.markcad.com/autocad/drawingscale.htm

kcore file

on a Redhat system, trying to find the cause of / filling up unexpectedly, I ran into this file named /proc/kcore that was quite big. Mysteriously, it couldn't be deleted, even by root. Which was good, since it turns out that it's actually a device. You'd think that kcore would be a core file that had to do with KDE, but in fact it's a wacky built-in that allows a person to dump active memory as though it were a file (using tools like od). Forums across the tubes are full of people who jumped to the same wrong conclusion that I did, and kind folks who explained the answer in ways interesting enough to preserve links to:

https://lists.ubuntu.com/archives/kubuntu-users/2005-May/000890.html
http://www.justlinux.com/forum/showthread.php?t=94027
http://www.linuxforums.org/forum/suse-linux-help/145869-kcore-file.html
http://www.linuxquestions.org/questions/ubuntu-63/prockcore-file-is-getting-bigger-and-bigger.-626078/
http://www.unix.com/unix-advanced-expert-users/107375-can-we-delete-kcore-file.html

Divide By 5 counter

For an FPGA, getting specific frequencies from the system clock involves things like "divide by 5". This turns out to be a little tricky if you want a real clock output with something resembling a 50% duty cycle. Some answers that I recently stumbled on include.

1. Use a PLL module if the FPGA has them, since they have multipliers and dividers built in that can make multiples or fractions of the input clock.

2. Use two binary dividers and combine them in novel ways that I don't completely understand yet. However, the following papers seem to explain it:

A SNUG paper from 2002 by ST Microelectronics, the original of which seems to not have the text contained in the still-barely-readable google cache:

http://74.125.95.132/search?q=cache:XH_x-8eBw-4J:www.scribd.com/doc/6868408/Clock-Dividers+vhdl+%22divide+by+5%22+counter+example&cd=6&hl=en&ct=clnk&gl=us

(original, seems to be working now: http://www.scribd.com/doc/6868408/Clock-Dividers)

Here seems to be some examples similar to the above, except the code makes no sense to me (particularly if x=n then x=x+1):

http://www.asic-world.com/examples/vhdl/counters.html

The first question in this quiz with answers looks interesting, but the problem in the outputs is not entirely clear:
http://www.ece.stevens-tech.edu/~bmcnair/SwTh-Sum04/quiz4-with-answers.pdf

Switching tabs

I keep futilely hitting Alt-tab to switch between browser windows, except that it's IE7 now and it uses tabs. Fortunately it turns out that IE7 responds to Ctrl-Tab to switch between tabs. Thank God.

http://www.online-tech-tips.com/internet-explorer-tips/how-to-switch-between-tabs-in-ie7-using-shortcut-key/