Archive for February, 2009

broken traces

2009/02/24

some how I’ve broken the traces to the jumper.

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swings

2009/02/21

vtune seems right with ~0v to 2Xv range but ~0.3v to ~2.0v for CPoutIF doesn’t seem right on the low end of the range.

small world

2009/02/20

603 == small. small enough so that the tweezers I had sitting around are so fat that manipulating them is non-trivial.

amusingly, resistors are now labelled in microdot format. I guess pros have scopes (micro that is) for this sort of thing.

can it

2009/02/20

VCOs (or the ones I got) come in packages and have a bunch of pins labelled. the reality is that there are three pins (vcc, vtune, and out) and thirteen things tied to ground (ie, the can).

maybe these are really not supposed to be hand soldered but doing the ground plane seems to be an exercise in how not to solder. pile on the solder!!

so pro

2009/02/19

I’m no soldering pro but when I buy something from a ‘factory’ I’d have expected better.

the ‘wider’ blobs on the bottom chip is where two pins were tied together. seem like a bad way to tie lines together.

fresh kill

2009/02/19

slow but non-vegetable prey.

questions

2009/02/18

when a question reads to me as:

I need to violate some constraints to test something other than what I think I’m testing. can someone help?

you know something has gone wrong between the querant and me.

ground plane

2009/02/17

this was what I was looking at as the input to the gain stage.

at 1v per division we’re looking at more than 0.5v of ‘noise’. that’s bad!!! the mic2506 is basically a switch with the 6v rail as input. I last checked the 6v rail when I soldered it so it was possible I screwed up something along the way.

then I looked down and saw the ground end of the probe was on the 4v rail.

a little futzing, and ahhh….

GIGO!

reading comprehension

2009/02/17

ad8402 looks similar (on paper) to ad8403, but a soic14 doesn’t look like a soic24.

i learned to solder when the rework guy wasnt around, but ‘dead bugs’ still suck. stop gap until I make another digikey order.

not pretty but functional (need to check if unused analog signal grounds should be tied down).

scope creep

2009/02/17

although creeping downwards. a friend has my ‘fell off the back of a truck’ scope so I got a smaller one for on-going project fun.