The DoubleDeka Ultrasonic VCO

sduck · Posted: Mon Jul 06, 2009 7:45 pm Post subject:

Another question -

Switch polarity. I'm using the bridechamber panel, with the 2 switches. I realize that if I get the polarity wrong, I can just spin them 180 degrees, but I tend to wire things pretty tight and getting things right the first time is nice.

S1 - I connect S1a to the middle lug, and S1b to which lug to make it work correctly with the panel?

The Lin cv ac/dc switch - which way should I wire this? One direction the signals being routed through a cap, the other way it's straight - which one's ac, which is dc?

Thanks!

frijitz · Posted: Mon Jul 06, 2009 8:55 pm Post subject:

sduck · Posted: Tue Jul 07, 2009 7:43 am Post subject:

Thanks!

johans121 · Posted: Thu Jul 09, 2009 12:31 am Post subject:

I just built #1 out of 2. This is one amazing module! The different timbres you can get out of it as a VCO are awesome, but I found that using it as a mod-source more than doubles its value. Audio rate modulation is amazing with this thing. Hooking one of its two VCO's outputs up to the V/O input on a filter and then tweaking the sliders creates some wicked sounds!

Great job Ian! Can't wait to get my second one built! Let the Audio Maelstrom begin!

(someone is going to have to put me away after I get these and my teezers going!)

ALSO several things of note regarding the PCB and the copy of the documentation that I received in 09/2008 (don't know if it has been updated):
1) The outputs on the PCB are labeled incorrectly. The pad marked OutA is really OutB & vice versa
2) The BOM lists a TL074 for U9 when it really calls for a TL072
3) On the BOM R30 is listed TWICE, the first value as 10kOhm & the second 1MOhm. R30 is supposed to be (according to the schematic 10KOhm)
4) R31 is not listed on the BOM, it is supposed to be 1MOhm (once again, according to the schematic)

-Jim

frijitz · Posted: Thu Jul 09, 2009 6:55 am Post subject:

frijitz · Posted: Thu Jul 09, 2009 7:51 pm Post subject:

sduck · Posted: Thu Jul 09, 2009 7:55 pm Post subject:

Just finished mine! Very cool sounding vco - haven't had a chance to do more than scratch the surface yet.

I didn't have any of the problems Johan had with the parts and docs I got from The Bridechamber. I was a bit worried about the out A and out B, but mine are labeled correctly. The way I had mine wired, if it needed fixing, it was going to be a big problem, and of course I did that bit of wiring the night before Johan posted about his problem.

The one thing I had to go back and fix is something that could be clarified a bit in the comments section - the wiring for the octave switches. For some dumb reason I assumed the letters on the pcb would correspond to the numbers on the switch - a=1, b=2, etc. But that's not how they work - it's backwards. Oh well, it didn't take long to fix.

fluxmonkey · Joined: Jun 24, 2005 Posts: 708 Location: cleve

almost done... anybody have a mouser part number for the 2 rotary switches?

b

sduck · Posted: Mon Aug 31, 2009 9:34 am Post subject:

I used 105-SR2612F-18-21RN from mouser for the ones in the pictures above.

Scott Stites · Posted: Sat Sep 05, 2009 9:39 am Post subject:

Hey Ian,

What is the frequency range of the undivided core HF output?

Tnx,
Scott

frijitz · Posted: Sat Sep 05, 2009 10:13 am Post subject:

Scott Stites · Posted: Sat Sep 05, 2009 10:30 am Post subject:

120 kHz

That's plenty!

Oh, someone expressed a wish over at MW for an SH3 type VCO, and I'm pretty sure the DoubleDeka core could easily pull it off using the HF output to drive the (very simple) shaping function of those synths. Even the PWM (Roland calls it chorus), which is just PWM derived from the shaped 8' sawtooth. In this case, one could just put the derived waveforms on sliders with a waveform selector for each slider. It wouldn't look all that different from the DoubleDeka we see today.

Cheerios,
Scott

frijitz · Posted: Sat Sep 05, 2009 11:31 am Post subject:

sduck · Posted: Mon Oct 05, 2009 2:56 pm Post subject:

Ack! A major problem has occurred. Why, I don't know. I hadn't used my doubledekka for a while, in fact had removed the power cable, as I'm short of power cables and needed it elsewhere. Plugged it back up, and I'm only getting one pitch out of it - the knobs and pitch cv ins aren't doing anything. The sync and ring in jacks do work, and the sliders are affecting the sound, so my guess is a chip has decided to die on me - but which one? Or something else? Any ideas are welcome.

Edit - a quick look at the scematics makes me suspect the OPA2227 is to blame - ? I used the part kit from Bridechamber - are these chips tempermental or anything?

frijitz · Posted: Mon Oct 05, 2009 3:12 pm Post subject:

sduck · Posted: Mon Oct 05, 2009 3:32 pm Post subject:

Yup, I'm getting a flatline from that chip. I've put one in my basket for my next mouser order. They have several different kinds - a OPA2227P, a OPA2227PA, and several others - any kind that's recommended?

frijitz · Posted: Mon Oct 05, 2009 3:44 pm Post subject:

sduck · Posted: Mon Oct 05, 2009 5:08 pm Post subject:

I put a TL072 in, and it works - at least the knobs and cv's work. I'll wait until I get the OPA2227 to calibrate it - that's what I was hoping to do today, but it can wait.

frijitz · Posted: Mon Oct 05, 2009 6:25 pm Post subject:

Well, you nailed it down pretty quick. thumleft

Don't see why that should have burned out -- the converter circuit is totally standard.

Ian

druish · Joined: Jun 23, 2009 Posts: 91 Location: New Paltz NY

HOLY @#$%! This thing is sooo badass! Just playing with the FM alone, this badboy RIPS!

KUDOS to Fritz! Very Happy

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Abby Normal · Joined: Feb 20, 2010 Posts: 66 Location: USA Audio files: 2

I can't help but this that this D-Deka module would look fantastic using those illumintated sliders, like the one in this link:

http://2.bp.blogspot.com/_FMBJEkaC8Lw/R7J5yYEgPCI/AAAAAAAAO_I/i8uoOUPaDs4/s1600-h/f5d0_1.JPG

synchroton · Joined: Mar 02, 2010 Posts: 20 Location: Milwaukee, WI USA

I'm wondering: would it be an easy mod to add sync to this oscillator? I'm thinking this might have some potential video synthesis application, given the high frequency of the core... But immediately it seems most useful if it could be sync'd to the horizontal or vertical refresh pulse...

frijitz · Posted: Sat May 01, 2010 1:40 pm Post subject:

synchroton · Joined: Mar 02, 2010 Posts: 20 Location: Milwaukee, WI USA

Heh! Guess I didn't look so closely. Just got excited when I saw how fast it was running...

Abby Normal · Joined: Feb 20, 2010 Posts: 66 Location: USA Audio files: 2

What size screws are needed for the front panel to slider mounting? I have 2-56 size screws, but they don't seem to fit. It seems like the wrong thread pitch.

I'm also wondering if I'm missing any documentation. All I have is the dd_board_doc.pdf. Is there anything else that I might be missing?

Thanks for any help...