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slabman
Joined: Sep 01, 2005 Posts: 102 Location: UK
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Posted: Mon Jul 13, 2009 2:37 am Post subject:
Digivox Subject description: Useful PDF on the Bernie Hutchins Electronotes website |
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There's a useful PDF on the Bernie Hutchins Electronotes website.
Quote: | The Digivox one note at a time music synthesizer' uses predominantly low cost RTL circuitry with a single low voltage power supply. The circuits have been reduced to the bare minimum required to produce a reasonable variety of electronic sound effects. The digital synthesis method results in a great simplification of the pitch and timbre generating functions and ease of tuning over most any 36 note range with all notes always in tune with respect to each other. |
There are some shift-register timbre generators and a keyboard controlled master oscillator that, if translated from RTL into CMOS, might yield useful building blocks.
PDF here - http://electronotes.netfirms.com/S007.pdf |
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slacker
Joined: Nov 18, 2007 Posts: 301 Location: England
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Posted: Mon Jul 13, 2009 1:48 pm Post subject:
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Very cool, thanks for sharing that. |
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DGTom
Joined: Dec 08, 2008 Posts: 211 Location: Adelaide
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Posted: Mon Jul 13, 2009 5:16 pm Post subject:
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the oscillators & the timbre generator look really interesting.
does anyone know where to get info on RTL in order to swap them out for CMOS?
All the logic is pretty easy, but some of the ICs seem to be represented by blocks, googles not been much help so far, but woah! these RTL chips go for some serious scratch these days! |
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droffset
Joined: Feb 02, 2009 Posts: 515 Location: London area
Audio files: 2
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Posted: Mon Jul 13, 2009 7:12 pm Post subject:
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Awesome info, thanks for that.
I don't have experience with RTL, would a NAND from this family act like a NAND in another?
Only one way to find out I suppose, I think I have NAND in TTL and CMOS. MIght need to NAND it up. |
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DGTom
Joined: Dec 08, 2008 Posts: 211 Location: Adelaide
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Posted: Tue Jul 14, 2009 7:25 pm Post subject:
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richard64 posted some vital info here that seems to have dissappeared in the wake of the spam attack.
*I think* it was something along the lines of RTL using 'negative logic' whereas CMOS uses 'positive logic'
So, in RTL High = 0 & Low = 1 so the NAND gates in these ccts are actually NOR gates in CMOS.
I BB'd the transistor sine wave generator yesterday, it worked... for awhile, quite a nice sine, but, it was a very sensitive arrangment & I could not get any control of the frequency except by touching the 330k resistor, altho running a pot to ground here didn't work as expected & neither did the VR in the schem. I played for awhile & it stopped working, I decided to come back to it |
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droffset
Joined: Feb 02, 2009 Posts: 515 Location: London area
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Posted: Wed Jul 15, 2009 1:43 am Post subject:
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Whoa, thanks for bringing that up(NAND/NOR), it hadn't occured to me.
DGTom wrote: | richard64 posted some vital info here that seems to have dissappeared in the wake of the spam attack.
*I think* it was something along the lines of RTL using 'negative logic' whereas CMOS uses 'positive logic'
So, in RTL High = 0 & Low = 1 so the NAND gates in these ccts are actually NOR gates in CMOS.
I BB'd the transistor sine wave generator yesterday, it worked... for awhile, quite a nice sine, but, it was a very sensitive arrangment & I could not get any control of the frequency except by touching the 330k resistor, altho running a pot to ground here didn't work as expected & neither did the VR in the schem. I played for awhile & it stopped working, I decided to come back to it |
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v-un-v
Janitor
Joined: May 16, 2005 Posts: 8933 Location: Birmingham, England, UK
Audio files: 11
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Posted: Wed Jul 15, 2009 1:54 am Post subject:
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I may be worth mentioning here that a very rare but well used 1970's classic synth called the Davolislint used a very similar architecture to this Digivox. The Davolislint was used by Cluster/ Harmonia and Soft Machine too There's a review of the Davoli at SOS mag. _________________ ACHTUNG!
ALLES TURISTEN UND NONTEKNISCHEN LOOKENPEEPERS!
DAS KOMPUTERMASCHINE IST NICHT FÜR DER GEFINGERPOKEN UND MITTENGRABEN! ODERWISE IST EASY TO SCHNAPPEN DER SPRINGENWERK, BLOWENFUSEN UND POPPENCORKEN MIT SPITZENSPARKSEN.
IST NICHT FÜR GEWERKEN BEI DUMMKOPFEN. DER RUBBERNECKEN SIGHTSEEREN KEEPEN DAS COTTONPICKEN HÄNDER IN DAS POCKETS MUSS.
ZO RELAXEN UND WATSCHEN DER BLINKENLICHTEN. |
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richardc64
Joined: Jun 01, 2006 Posts: 679 Location: NYC
Audio files: 26
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Posted: Wed Jul 15, 2009 6:59 am Post subject:
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I built this!
Well, part of it. OK, I only used the VCA/VCF and the Envelope Generators.
http://www.sdiy.org/richardc64/rtlsynth/rtlsynth.html
The rest of the circuitry seemed to me to be too complex for a mono instrument. Using a shift register to create different tonal qualities was intriguing, but the skimpiness of information about that part of the DigiVox put me off, so I used simpler methods.
(My post about negative logic wasn't a casuality of the spam clean up: It was deleted by ME. Although I am certain that the MC724 is a NOR in the more usual positve logic, I can't be certain about the other gates in the design.)
edit: updated link _________________ Revenge is a dish best served with a fork... to the eye Last edited by richardc64 on Tue Aug 24, 2010 4:06 pm; edited 1 time in total |
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richardc64
Joined: Jun 01, 2006 Posts: 679 Location: NYC
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DGTom
Joined: Dec 08, 2008 Posts: 211 Location: Adelaide
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Posted: Thu Jul 16, 2009 12:01 am Post subject:
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richardc64 wrote: | (My post about negative logic wasn't a casuality of the spam clean up: It was deleted by ME. Although I am certain that the MC724 is a NOR in the more usual positve logic, I can't be certain about the other gates in the design.) |
sorry.
Thanks for the info & links. |
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