No-chip analog delay

[ExpAnonColin]

So here's an idea.
We all know that BBD chips are basically just a whole lot of capacitators wired in a specific way....  So....  Let's see.  You could probably get a 10"x10" circuit board, and say that every square inch out of 100 would have about enough room for 10 little nonelectrolyte caps.  That's ABOUT 1000 per circuit board... 3 capacitators makes 1 stage, basically, so if we had 3 boards we'd have a 1024 stage BBD, perfect for chorus!  12 boards and we'd get a good ol' 4096 stage BBD for about 200ms of delay...  24 boards and we'd get even more delay!  Oh, the possibilities.  Plus, the box would probably only have to be abuot 1 foot cubed!  Now, let's calculate cost...
24,000 capacitators: about $1200... on ebay you could get lucky and probably get them for around 400 after a few auctions.  Come on now, that's pretty cheap.  Who's with me?






-Colin

[puretube]

...plus at least 2 transistors per capacitor (or tubes, like done so in the late thirtees...), wired in a specific way...



//www.puretube.com

[ExpAnonColin]

...plus at least 2 transistors per capacitor (or tubes, like done so in the late thirtees...), wired in a specific way...



//www.puretube.com

Hmph... In the datasheets, in the circuit diagrams, there aren't any trannys at all.
-Colin

[puretube]

but they are in the BBD-chips...I can even hear them switching thousands of times per second... maybe they might be called FET`s or CMOS switches (or triodes for discrete BBD), but they are in there... (sampling and holding). (Except in the oil-can/storage-disk technique...).

Or ask Mark H.


//www.puretube.com

[Peter Snowberg]

I would go surface mount for such insanity. The noise would probably render it useless after a coulpe hundred stages at most, unless you use really low noise transistors.

Either that or if you can scrape together a little more cash, you could always draw a chip up in VHDL and have it fabbed by Mosis. It would only come to about $300 per chip if you get 15.

-Peter

[idlefaction]

i like the tube idea.  512 12AX7s plus sockets and a power supply with enough juice would probably be about $100,000.....  mmmm......

anone have a schem for ENIAC?  

[Gus]

look up the ABC computer.  Atanasoff Berry Computer.   This was built before Eniac.  The memory was a type of DRAM caps were mounted to disks radial center was common for the caps the other end of the cap was brought to a point on the rotating cylinder the caps were charged recharged if needed sensed etc.

Now lets think preformance art. You make an mult stage cap array you build it and stagger the contact points.  there is the time delay sample for your effect.  now you build electronics that filter the input and ouput (maybe by sensing the rpm of the cylinder by an absoulute encoder or a two phase with a once around etc.......) for antialising.  You build a charge, sense, discharge circuit etc.............

now the fun part run the cylinder from a variable speed control you can have all types of inputs controlling it.

O the madness and the fun.

Look at old computer circuits.   memory storage mercury delay lines,  CRTs using the decay time of Phospherus(sp) for strorage.

Gus

[brett]

While you're at it (you've already got 3 caps and 2 transistors per stage, right?) you might as well put in an LED display driver (e.g. LM3915) at every 10th or 50th stage.... the idea being that you use 15 slightly different coloured LEDs for different levels (say blue for lowest, green for mids, amber for high levels, and red for near-clipping).   Then you'd get this great, flashing, multi-coloured visual effect too :!:  Wow :twisted:

Send us a picture when you get it done!

[ExpAnonColin]

While you're at it (you've already got 3 caps and 2 transistors per stage, right?) you might as well put in an LED display driver (e.g. LM3915) at every 10th or 50th stage.... the idea being that you use 15 slightly different coloured LEDs for different levels (say blue for lowest, green for mids, amber for high levels, and red for near-clipping).   Then you'd get this great, flashing, multi-coloured visual effect too :!:  Wow :twisted:

Send us a picture when you get it done!

That'd be a lot of fun.  The case would be big enough to accomidate all of the LEDs, that's for sure

-Colin