Grounded: March 2008 Archives

AMP D-SUB Crimping tool for sale

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amp_58074_tool_9pin.JPGI was going through my tools last night, and I came across this gem that some of the more serious builders might appreciate for wiring up a bunch of serial or parallel connectors. I even have a 25 pin male and female connetor to through in (I also had a male 9pin, but I crimped a wire in it to test the tool - works beautifully). Other then trying it out, I have never used it, and after seeing what they sell for new, I figure the few times I need to make a d-sub connector I'll just solder the wires manually. I could use the cash to buy plane parts.

Both Digikey and Jameco still stock these, so I'm thinking there are people out there who would appreciate one for less then full blown retail.

Total price from Digi-Key $266 plus taxes & shipping (Jameco was over $400! Yikes, who shops there???).

In the end, this tool is a time / money trade off. Those with money and little time will appreciate it, those like me with little money and (hopefully) more time can't justify the cost - hence the reason I'm looking to sell it.

As for the cost of the connectors, based on this page from Digi-Key,

The 9 pins seem comparable (male connectors are the same price), however, they do get quite expensive compared to the soldered connectors as the number of pins rise.

Any takers for $100 US plus shipping? Theres a good chance it will be put up for sale on eBay over the next few days.

Binary Clock project - Using an obscure MC838

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I'm trying to build a binary clock with some surplus digital logic chips I have laying around. The chip of choice it seems would be the 7490, of which I have 1 that works properly and 1 that seems to only work if I leave it in the default mode of counting from 0 to 9. I also have a number of chips stamped with MCC838, which turns out to be a decade counter like the 7490.

The main exception is the 838 has 4 inputs to explicitly set the bits with and a single reset line. I need to configure 3 counters to reset after reaching 5 (on 6 reset to 0). With the 7490, just tie the second bit to one reset and the third bit to the other reset and assuming the chip works, it counts 0, 1, 2, 3, 4, 5, 0, ....

Studying the spec sheet I could find on the MC838 leads me to believe that by using a NAND gate on bits 2 & 3 the result should nicely drive the CD (reset) line from High-to-Low and hence reset the counter back to 0. However, that is not what is happening. Hear is the observed output:

1 2 4 8 NAND

0 0 0 0 1

1 0 0 0 1

0 1 0 0 1

1 1 0 0 1

0 0 1 0 1

1 0 1 0 1 - at this point, the next clock should create 0110 (6) and the NAND goes low (0) which should reset the 838 counter and start over. However, the counter just skips 6 & 7 and carries on with 8 as follows...

0 0 0 1 1

1 0 0 1 1

0 0 0 0 1

Any ideas?

Happy Pi Day!

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Today is none other then Albert Einstein's birthday (happy 129th birthday!), noted as 3/14 (or 3.14) and hence Pi Day. So, make sure tonight for dessert you have a big piece of pi[e]!

ATI Radeon 9600 for sale - sold!

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ati_9600.jpgI am currently selling an AIT Radeon 9600 All-in-Wonder video card complete with drivers, remote and cables. This is the one with the built in TV tuner and video capture hardware. I never did end up using the TV tuner part and when my computer received an unscheduled upgrade last month to PCI-X, the AGP card quickly had no useful value to me any more. The card is (was) for sale on eBay. Thanks to all who bid!

Start of a new day^h^h^hsite

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Well, here's something I've wanted to do for quite some time. Start using a real blogging tool. So this short and sweet post is just to get things started. I will leave all the pages, pics, etc. where they are for those deep linking in from other sites.

The original start page is still available - I'll leave it around for a while (I rarely delete anything).

For those that might have missed it, I'm asking for help in identifying an old airspeed indicator I purchased off eBay a few years ago. Here's some photos:


airspeed1.jpg  airspeed2.jpgairspeed3.jpg




UPDATE - March 7, 2008

Thanks to Ed (a member of the group), I have some more information regarding this instrument. A site call has a Lancaster ASI about 3/4 down the page dated 1943 that looks identical to mine (except theirs doesn't have a broken mount).

SpitfireSpares has theirs listed at 115 British pounds, or about $225CDN. I think I'll put mine in a safe place for now.