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SAD1024 - Analog Delay (?!)

A project log for Random Ridiculosities and Experiments

Sometimes yah's just gots tah try somethin', regardless of whether it'll become a full-fledged "project"...

eric-hertzEric Hertz 02/06/2017 at 13:456 Comments

Just found this groovy thing in my rarely-accessed analog-ICs bin.

A variable-analog-delay!

http://www.pmerecords.com/Docs/Archer_SAD-1024_Tech_Data.pdf

I like the description: "an analog-sampled data device which lies between linear and digital"

I have yet to wrap my head around how it works... though I think it's similar to CCDs, which I also have yet to wrap my head around... (How on earth is the *entire* charge supposed to make it from one end to the other, wouldn't all the intermediate capacitors spread it out?).

Anyways, pretty cool looking.

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I also located 3 LM3914's (and a LM3915)... And, I think I might have another 3914 in another parts-box... And unless I made a horrendous mistake in a move, I should already have a wired-up 20x20 LED matrix from nearly 20 years ago (Jeeze I'm old!). So there may be some messing around with Lissajous and LEDs in my future.

Thanks #LED Oscilloscope Mk. II and #RGB LED Oscilloscope for the distraction!

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UPDATE: Bah... I can't find the matrix, and soldering 400 LEDs is a daunting prospect. Maybe later.

Discussions

Thomas wrote 02/06/2017 at 18:20 point

Oh great! In the 80s this was known as an "Eimerkettenschaltung" in German - a bucket-chain-circuit. Add some photo diodes, and you have a CCD line camera.

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Eric Hertz wrote 02/07/2017 at 02:57 point

I think they're called "bucket brigade" in english. I should look those up again and see if I can grasp it.

I dig the fact they're analog(ish).

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Ted Yapo wrote 02/06/2017 at 16:34 point

I remember those analog delay lines - they replaced long mechanical springs in reverb effects at one point.  I'm sure it's all DSP these days...

What about pre-made 8x8 displays:

8x8 red LED display ebay listing

I don't like the space between pixels, but that's a matter of taste, I guess

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Eric Hertz wrote 02/07/2017 at 02:47 point

Cheap! But I should probably save the money for something I *can't* build with supplies-at-hand. 

Lacking solder-protoboards larger than a 40-pin DIP, though--and recurringly putting off other projects due in part to this fact--this project-idea may be another "pro" in favor of placing an order. Wonder if the drilling-robots will come after me.

Rather'n file off the T1-3/4s' lips, maybe I'll space 'em wider and use cardboard "comb" light-shields. Hopefully these old guys are bright enough for a diffuser, 'cause seeing yours, that really is a nice effect.

Or, I did just buy a bunch of raster-drawn LCDs... a couple (555?) timers, a couple R/C networks for triangle-ish waves, and a comparator should give a pretty decent 'scope-like effect. Two comparators per channel, even more-so. Three colors possible... Or even the possibility for 6 channels if half-shades and two lines of the same color are acceptable. Hmm... But Lissajous would be difficult, to say the least. and full-screen scan-rates may be limited to ~80Hz *160pixels = 12.8KS/s... a bit low for audio... Maybe powerline monitoring.

Maybe I should dig out the ol' 555 Mini Notebook.

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Ted Yapo wrote 02/07/2017 at 13:18 point

Speaking of the drilling robots - I bet you could chuck a T1-3/4 LED body into a cordless drill (or lathe) to remove the lip in no time.  Just wear some good safety glasses :-)

I found some cheap solder proto boards on ebay at one point.  I have no idea how they get so many holes in there so cheaply.  I'd guess the phenolic boards were cast with holes, but then they have those little copper rings on them.

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Eric Hertz wrote 02/07/2017 at 17:25 point

Indeed, at the point of chucking'em'up, it'd probably take longer to do that than the actual "lathing" action.

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