Buchla Source of Uncertainty 266

numbertalk · Posted: Wed Jan 07, 2009 9:44 am Post subject:

Not too late - thanks!!!!!

Scott Stites · Posted: Wed Jan 07, 2009 9:46 am Post subject:

Abra's pretty cool. They got a lot of CMOS, so stock up to meet your minimum. I think I went over $50 once, and they sent me a cool little DMM.

Scott Stites · Posted: Wed Jan 07, 2009 9:51 am Post subject:

vtl5c3 · Posted: Wed Jan 07, 2009 10:03 am Post subject:

numbertalk · Posted: Wed Jan 07, 2009 3:04 pm Post subject:

funkyfarm · Posted: Sun Jan 11, 2009 2:03 am Post subject:

SRV requires +8V +10V +12V +15V AND -15V.

TO-92 regulators are needed (7808 7810 7812) ?

vtl5c3 · Posted: Sun Jan 11, 2009 9:04 am Post subject:

All of these PCBs only require +/- 15V and GND. The +8V is a typo. +10 is provided by one of the opamps, just like on the original 266. Buchla used +12V for powering LEDs. I just used +15V since that seemed silly to me. No extra regulators required.

funkyfarm · Posted: Sun Jan 11, 2009 9:54 am Post subject:

ouf !

(I have 2n1711 trannies if you want 12V LED...)

ericcoleridge · Joined: Jan 16, 2007 Posts: 889 Location: NYC

I just got the noise ICs pulls I bought off e-bay some weeks ago. So, if you requested one, now's the time to send me your address-- if you still want it. Unfortunately, I can't guarantee that everyone who wanted one will get one-- as I had about twice as many requests as chips-- but I'll honor your requests in the order that I received them. If someone doesn't need it anymore, I'll give it to the next in line.

vtl5c3 · Posted: Sat Feb 07, 2009 12:03 pm Post subject: 266 S&H PCB (4 of 4)

OK, here it is! The last installment of the Buchla 266 press & peel layouts.

Some notes:

1) The original uses a 2N4341 for the portamento JFET. I think that they are now hard to find. I used a 2N4391 and it works just fine.

2) I added pads for optional output LED drivers. The parts are marked with * to emphasize that they are optional.

3) The expo converter on the portamento circuit originally used an AD821 matched pair, now obsolete. I think that I might have used a MAT03 in its place. It's not a critical circuit, so you could get away with 2N3906, BC560, etc... matched or unmatched.

I'll post some mp3s later. I think I still owe you some for the 266 Fluctuating Random Voltages too.

Anyway, I hope that this is of use to some of you. If you build any of the 266 sections, please share your work. I'd like to see how others interpret the SOU for themselves!

266_4_Parts_fixed_ 11132011pdf.pdf

Description:

PCB 4 - S&H and VC Slew. Fixed errors. 11/13/11

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266_4_Parts_fixed_ 11132011pdf.pdf

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266_4_PCB_fixed_ 11132011.pdf

Description:

PCB 4 - Traces. Fixed bugs 11/13/11.

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funkyfarm · Posted: Sat Feb 07, 2009 12:40 pm Post subject: Re: 266 S&H PCB (4 of 4)

Luka · Joined: Jun 29, 2007 Posts: 1003 Location: Melb.

thanks romeo!
ill be building these for sure

ericcoleridge · Joined: Jan 16, 2007 Posts: 889 Location: NYC

ericcoleridge · Joined: Jan 16, 2007 Posts: 889 Location: NYC

OK, I'm just about done populating Board 3, but I'm not sure about the VTLC3 orientation. I never really understood how to read vactrols in schematics-- so I'm not sure about placement on this PCB.

Looking at the VTLC3/4s on the parts placement PDF, I see that the slanted corner corresponds to the + pin of the LED--- but if that's true for the VTLC3, it seems to me that it needs to be placed upside down? I've never had a build where the Vactrol is placed print side down-- so I just want to double check here. Am I completely confused?

Can anyone help me with the orientation of the vactrols on Board 3? I appreciate it.

ericcoleridge · Joined: Jan 16, 2007 Posts: 889 Location: NYC

I think I got on my own. I wasn't looking close enough at the placement PDF-- it looks pretty clear now. I wasn't using my noodle. It looks like the VTL5C3 Vactrol's "LED" side is facing down when looking right side up at the placement PDF.

numbertalk · Posted: Mon Feb 09, 2009 6:23 pm Post subject:

Sorry if this is a stupid question, but do these 4 boards connect to each other/are they normalized at all, other than maybe a power buss between them?

vtl5c3 · Posted: Mon Feb 09, 2009 6:52 pm Post subject:

It's quite possible that the vactrol is upside down. I don't remember right now. You can trust the orientation on the parts layout, though.

vtl5c3 · Posted: Mon Feb 09, 2009 6:54 pm Post subject:

They don't really connect to one another. They are laid out to be independent of one another. You don't have to build a complete 266 if you don't want to. Of course they can all connect to the same power buss.

numbertalk · Posted: Mon Feb 09, 2009 6:58 pm Post subject:

Thank you and thanks for these projects!

ericcoleridge · Joined: Jan 16, 2007 Posts: 889 Location: NYC

vtl5c3 · Posted: Tue Feb 10, 2009 6:35 am Post subject:

Hi Eric,

The slanted corner is the cathode, i.e. the - side. When in doubt, check the datasheet.

As far as troubleshooting goes, have you checked to see if you're getting noise out of the MM5837? I'd start there and work my way down the line.

ericcoleridge · Joined: Jan 16, 2007 Posts: 889 Location: NYC

yep, that's where I started. So, it could possibly even be the IC. But, I only spent a minute testing it, so I'll find out more later.

ericcoleridge · Joined: Jan 16, 2007 Posts: 889 Location: NYC

I have not had an opportunity to test again yet. But I just noticed that, not my VTL5C3, but my VTL5C3/4s are incorrectly oriented. Unless I'm mistaken, the VTL5C3/4s on this PCB need to be placed print side down.

I only powered the board for a minute, could this have burned the vactrols?

I also wonder if this would explain the Noise section not working?

vtl5c3 · Posted: Wed Feb 11, 2009 7:44 pm Post subject:

I'm not sure about the vactrols, but if they're like LEDs, it's possible that they are burned out.

I kind of doubt that it would have caused the noise section to fail. If you want to test the noise ICs, you could try breadboarding something like the 5837 circuit on this page:

http://www.decodesystems.com/pink-noise.html

If you were to use that to test the chip, I don't think you'd need to include any of the stuff to the right of the IC's output resistor.

If you can wait until the weekend, I'll pull my 266 out of the cabinet and take photos of the individual boards. Maybe that will help.

R.

[Edit] Another idea: if you have another noise source, you can pull out the 5837 and inject it into the circuit. Remember that I added pads for a jack to allow an external noise input. Just be sure to pull the 5837 out first.