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Author Topic: Oil Can Echo Schematic Questions  (Read 26231 times)

Andy Peters

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Re: Oil Can Echo Schematic Questions
« Reply #60 on: July 27, 2009, 07:38:57 pm »

Scott Raymond (Scott R) wrote on Mon, 27 July 2009 07:39

John Roberts  {JR} wrote on Sun, 26 July 2009 08:52



Ah yes Ciacira's cellar..  The MacGuyver of circuit design...   A digital memory will have only two output states for full white or full black pixels. Remarkable that it worked at all. Many semiconductors are light sensitive.  

My comment was that I didn't recall Micron working with CCDs, while there were other companies than Reticon messing with CCD for other than analog shift registers.



I don't recall Micron being involved with CCDs, either, although they did have a CMOS image sensor operating which was recently spun-off into something called Aptina.


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Yes, I really looked forward to his articles every month.  I think I almost came to the point of building this camera back then.  Getting greyscale out of it was possible with the method of varying the "Soak" time of a series of exposure cycles and then averaging the results of each "pixel" (capacitor cell or memory location) to come up with a grey level.  The capacitor cells would discharge at a rate proportional to the brightness of the light so it was a relatively straight forward process of writing 1's to all the cells (memory locations) letting them soak for a period of time and then start refresh cycles to lock the values in while they were read out to create the image.  Those above the threshold voltage were one's, those under were zero's.


Ah, a clever trick. One could call "soak" time simply the integration time, although you do multiple "exposures."

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It's really mind blowing to look back at this 256 x 128 sensor and see where things have gone now with the 10, 12 and higher magapixel camera's (apostrophe fail)!!!  Cool


Only 12 Mpix? Hah.

Quote:

EDIT...Added Note:  Most of the chips back then weren't suitable for image detection as the physical layout wasn't suitable for easy imaging.  The Micron device was designed as (2) 256 x 128 arrays only one of which was used in this camera.  It also had a quartz window installed over the chip.  I expect they were exploring a new and changing market but where it went for them I don't know.


Sounds like that Micron part had a frame-transfer readout. Basically, half of the sensor is exposed to light and the other half is kept in the dark. You do your integration, then transfer the entire frame to the "dark" side. Then you can read out the dark side while starting a new integration on the light side. That's useful if you need to minimize dead time between exposures (you overlap integration and readout) at the cost of having half of your sensor area unusable for imaging.

(EDIT: I just read the article. It's not a frame-transfer device. It appears as if the part is built with two die in the package, side-by-side.)

Nowadays you can do what's called a "rolling reset" which means that you reset a row immediately after reading it, which makes the integration time effectively the frame readout time, and readout and integration overlap.

-a
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"This isn't some upside down inverted Socratic method where you throw out your best guess answers and I correct your work." -- JR


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Scott Raymond

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Re: Oil Can Echo Schematic Questions
« Reply #61 on: July 29, 2009, 09:49:46 pm »

Andy Peters wrote on Mon, 27 July 2009 18:38


(EDIT: I just read the article. It's not a frame-transfer device. It appears as if the part is built with two die in the package, side-by-side.)

Nowadays you can do what's called a "rolling reset" which means that you reset a row immediately after reading it, which makes the integration time effectively the frame readout time, and readout and integration overlap.

-a


Soooo... Are you ready to go back to the good ole days?  Smile
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Andy Peters

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Re: Oil Can Echo Schematic Questions
« Reply #62 on: July 29, 2009, 10:10:00 pm »

Scott Raymond (Scott R) wrote on Wed, 29 July 2009 18:49

Andy Peters wrote on Mon, 27 July 2009 18:38


(EDIT: I just read the article. It's not a frame-transfer device. It appears as if the part is built with two die in the package, side-by-side.)

Nowadays you can do what's called a "rolling reset" which means that you reset a row immediately after reading it, which makes the integration time effectively the frame readout time, and readout and integration overlap.

-a


Soooo... Are you ready to go back to the good ole days?  Smile


No effin' way.

-a
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"This isn't some upside down inverted Socratic method where you throw out your best guess answers and I correct your work." -- JR


"On the Internet, nobody can hear you mix a band."

Paul Reid

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Re: Oil Can Echo Schematic Questions
« Reply #63 on: January 25, 2011, 09:18:32 pm »

Art Welter --

Are you still looking at this oil-can?

> the signal to noise ratio is about 1/1

S/N is about the media, the Drive Level, and the recovery losses.

The tube circuit has oddities but is not hard to read.

The input is two HIGH-gain stages. The obvious intent is to bring e-guitar up to about 100V rms into a very high impedance load (prehaps less than 50pFd, plus some megs of trim-pots). You won't get this level from line-amps or line transformers; indeed transformers work poorly into such loads. The "simple" answer is to build the tube-amp. If you have Line (not e-guitar), only the 2nd stage is needed. Set peak level near clipping.

The recovery amp is very specialized, and may be your bigger problem. The 4.7Meg grid resistor is boot-strapped by the cathode, and a second cathode. Counting on thumbs it looks like 50 MEGS input impedance. Chewing the computer, I get numbers like 30Megs with less than 1pFd(!) input capacitance. It's odd, and surely necessary to recover signal from such a hi-Z source.

You will not get this level of light loading from any common studio preamp. A condenser mike head-amp could work, or something like that simplified to bootstrap JFET on 18V-24V supply. Or the tubes. The teeny grid capacitance suggests that (like a condenser mike head) the stray wiring capacitance must be VERY small, the recovery amp should be up-against the tank, and room-buzz will be a problem.

There were, however, 25V transistor versions:
http://www.el34world.com/charts/Schematics/files/effects/tel ray_delay_echo_reverb_oilcan.pdf
http://www.el34world.com/charts/Schematics/files/effects/tel ray_echovolume_evo-1_oilcan.pdf
http://www.el34world.com/charts/Schematics/files/effects/tel ray_electrostatic_delay_line_oilcan.pdf

The disk surface must be a thin insulator on a conductor. VERY low self-leakage. Preferably with high dielectric constant. Your disk is Aluminum. The obvious surface treatment is anodize, Aluminum Oxide, much like an electrolytic capacitor except without (necessarily) a conductive liquid electrode. Indeed patent 2,892,898 cites aluminum oxide on aluminum. (Patent 3,072,543 rubs glycerine into AlO... dang-near an electrolytic cap.)

Surface must be DRY. Oil must be dry.... high-voltage oil is commonly heated above the boiling point of water for a few hours before final use. Scratches do little harm. Water on a soft cloth with a good dry does no harm. Harsh scrubbing will remove the anodize film, and the raw aluminum in everyday air will grow-back a coarse self-anodize which will work poorly or not at all.

Oil VooDoo may be the trick which raised the can from a toy into a product. Dry-rub wears the surface or wipers, and upsets electrons. Lubrication helps life, and also can improve dielectric coupling.

In addition to the basic delay, there is system-stuff. Input audio is tapped to a "Direct Signal" pot and mixed to output. Recovery amp is tapped for "Echo Level" pot mixed to output. Basic stuff, though the 0.01u+5K in the echo out path suggests EQ.

And then there is regeneration. The double cathode follower second plate (to bypass Miller trouble) has a high-gain output potted onto the same line used for Direct output. This works because the input first stage plate is very high impedance. The regen pots look to be wired backward (wiper-in), it works better this way.

The "mudflaps" should touch the surface more like "windshield wipers". The contact area must be large for good energy transfer. The length in direction of motion must be small for good high frequency response. Same as tape: the gap is 0.1" one way and 0.001" the other way. And like tape, the play azimuth must be aligned with the record azimuth. This must be difficult with rubber mudflaps.

http://www.google.com/patents  -- 2892898 - 3072543 - 3215911
http://web.archive.org/web/20050419134852/http://www.geociti es.com/tel_ray/pictures.html

http://www.el34world.com/charts/Schematics/files/effects/tel ray_ad_n_echo_oilcan.pdf
http://www.el34world.com/charts/Schematics/files/effects/fen der_echoreverb_II_oilcan.pdf
http://www.el34world.com/charts/Schematics/files/effects/fen der_echoreverb_III_oilcan.pdf
http://www.el34world.com/charts/Schematics/files/effects/tel ray_deluxe_organtone_oilcan.pdf
http://www.el34world.com/charts/Schematics/files/effects/tel ray_echo-ver-brato_oilcan.pdf


Side-note: "I don't think ESD conductive rubber was around in the 60's"-- in the 1962-1965 timeframe I was shown a bumpy rubber plate the size of a punch-card, told it was mildly conductive, and that it was part of a card-reader. Also patent 2,892,898 speaks of "elastic conductive" material and "neoprene impregnated with graphite"; patent 3,072,543 mentions "conductive rubber".  Tire-rubber has been doped with powdered carbon since forever; not to the point of great conductivity (they put other stuff in also), but enuff so that sorta-conducting rubber would be obvious.
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Art Welter

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Re: Oil Can Echo Schematic Questions
« Reply #64 on: January 26, 2011, 05:36:52 pm »

Paul,

Thanks for the reply, the high input voltage needed, and the specialized recovery amp  would certainly explain why the S/N was so bad when I tried using pre amps and small power amps, even with transformers.

Oil can echos sound really low-fi even in pristine condition, so I really have no interest in building a special amp for it, but glad to finally hear why I couldn't get it to work as well as it should.

Patents are interesting too, thanks for clearing up the details!

Any amp builders wanting this goofy thing are welcome to PM me, I’d be happy to trade or sell it.

It would have to ship with the special oil taken out though, the thing leaks if it is laid motor side down  Laughing .

Art Welter
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Scott Raymond

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Re: Oil Can Echo Schematic Questions
« Reply #65 on: January 26, 2011, 10:16:43 pm »

Art Welter wrote on Wed, 26 January 2011 16:36



It would have to ship with the special oil taken out though, the thing leaks if it is laid motor side down  Laughing .

Art Welter


You can't put "This Side UP" stickers on it? Wink

Scott
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Art Welter

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Re: Oil Can Echo Schematic Questions
« Reply #66 on: January 27, 2011, 12:26:41 pm »

Scott Raymond wrote on Wed, 26 January 2011 20:16

Art Welter wrote on Wed, 26 January 2011 16:36



It would have to ship with the special oil taken out though, the thing leaks if it is laid motor side down  Laughing .

Art Welter


You can't put "This Side UP" stickers on it? Wink

Scott


I'll do that for you, Scott, and include one free oil change kit.
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