Diode Function Generator (a la Analog Computers)

Ricko

(Did I already post this?) I was looking at Analog Computers a couple of months ago, and worked up this version of a Diode Function Generator. Think of it as a more variable version of a diode waveshaper. (There is some interested archival material on the web, from the 50s and 60s!)

It would be easier to use if it could be used like a graphic EQ (like the bar display with dither circuit). As it is, each step effects every step to the right of it.

I haven't built this, just simulated it in TI-SPICE. There is a full version. (It is also a simplified version at http://electro-music.com/forum/topic-28527.html )

Cheers
Rick

DIODELADDERWAVESHAPER2.JPG

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Schematic of full shaper

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Ricko · Posted: Sun Feb 22, 2009 12:42 pm Post subject: Some references

I dug up some references for anyone interested. I cannot find the main reference, which was in a book online (it had a resistor ladder rather than a diode ladder, but I couldn't get it working in SPICE yet)

A 1952 reference from The Simulation Council
http://www.scs.org/history/SimCouncilNewsletters/1952/SCN-Dec52.pdf

A different arrangement for fixed diode function generators
http://accelconf.web.cern.ch/AccelConf/p73/PDF/PAC1973_0567.PDF

Also
http://www.scs.org/history/SimCouncilNewsletters/1963/SCN-Mar63.pdf

Cheers
Rick

andrewF · Posted: Sun Feb 22, 2009 3:47 pm Post subject:

Hi Rick
thanks for posting those. After building Ian's and others chaos circuits, i am developing an appreciation for the subtler uses of diodes.
here's an old Heath diode FG
this one has been on my list for a while

heath function gen pic.jpg

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heath funcgen schem.jpg

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loss1234 · Posted: Sat Oct 16, 2010 8:40 am Post subject:

for those into analog computers, here are ALL the archives of that newsletter

http://scs.org/history/SimCouncilNewsletters/Default.htm

frijitz · Posted: Sat Oct 16, 2010 2:38 pm Post subject:

Here's a breakpoint shaper from Jim Patchell:
http://www.oldcrows.net/~patchell/synthmodulesII/march2004/200-1002.pdf

andrewF · Posted: Sat Oct 16, 2010 10:00 pm Post subject:

Funny this shows up again
I have spent some time this week examining the diode breakpoint shapers in Mr Patchell's Vocal Filter - much the same as the circuit posted above by Ian.

and
(also this week) started point to point connections for the Heath diode function generator using a rack of hewett-packard 5725 pentodes.

100th monkey effect?