Making Music with the 566 now available

[Tim Servo]

Hey everybody!

Sorry for the delay, I was taking a week off and hangin' with my homies... well, with my kids and wife and cats (which for me counts as My Homies).

Here's the latest Parts List for the 566 VCO. I'll also be sending this, along with a schematic and parts placement diagram to customers. The first batch of boards sold very quickly (thanks to all!) and a second batch is on the way.

I'd also like to thank Dave Brown, who not only did a lot of work on the board and the parts list. Dave definitely gets a "Friend of Smoke" award. One thing I did change was the cap for the LFO range, listing a 0.47uF polyester film cap. The main timing cap (Audio Range) is a polypropelene unit, which will have better performance and temp stability. I chose a polyester cap for the LFO timing because it has the desired value in a reasonably sized package, and should be more than adequate for LFO applications. You may want to experiment with an even larger cap to lower the LFO range. I'm going to try a 1uF, and I'll report on the results.

Anyway, take a look and ask away if you all have any questions.


Tim (I'm back, baby!) Servo

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566-01 Parts List--2007-DEC-30.pdf
Description:	Magic Smoke 566 VCO. For Version 01 board. December 30th, 2007	Download (listen)
Filename:	566-01 Parts List--2007-DEC-30.pdf
Filesize:	552.07 KB
Downloaded:	786 Time(s)

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[davebr]

I tried a 1 uF, then a 2.2 uF and then settled on a 4.7 uF for the LFO cap. It gives me a range of 0.02 to 120 Hz. The VCO has poor linearity at low control voltages, so with the 4.7 uF, the waveform shapes up nicely at about 0.33 Hz.

Dave

[loss1234]

thanks dave
but i was under the impression that these pcbs would come with a schematic.
i appreciate you posting your modified version and this is the first parts list i have seen for the board.

i will definitely check it out as soon as i have the original to compare it to.

happy new year

[6079smith]

Just so I'm clear, Q6 (the FET) is rotated 90° anticlockwise? That portion of the schematic doesn't seem to be in the 566 book, unless I'm blind...

Anyhow, nice work Dave, I'll probably take a leaf out of your book for the front panel design.

[davebr]

It's almost visible in the photo on my page.

The flat portion of the FET points directly towards the cathode of D2. The middle pin goes into the upper left hole closest to the Q6 silkscreen nomenclature. The other two pins go on either side and fit normally into the other two holes. So yes, I would say it is rotated 90 degrees counter clockwise

I annotated the orientation in the photo of my noise modifications.

Dave

[Tim Servo]

The doc package for the TH-101 566 VCO boards has gone out, so you all should have a corrections document that shows how C4 and Q6 are mounted. Also, thanks to Dave Brown for posting some nice clear photos!

More docs are on the way (connector wiring, calibration), but all TH-101 owners should now have the schematic, parts list, parts placement and corrections docs. Thanks to all who have bought boards so far, and to those of you who are waiting for more boards, the next batch is on it's way!


Tim (workin' on the docs, Boss) Servo

[Tim Servo]

Just a note: we have a new batch of 566 VCO boards in stock, so they're available again for those who were waiting! Also, the doc package is finished, so all that info is ready to go.

BTW, thanks again to all who have placed orders!


Tim (working in the shipping department today) Servo

[philpeery]

Hey Tim,

How does one get their hands on a couple of these boards? I went to the magic smoke web site, and do not see any info on ordering the 566 oscillator boards.

Thanks!
Phil

[Tim Servo]

Hey Phil,

Well, first you have to know the Secret Handshake. Then there's the matter of a "donation" to the 'send Servo to Tahoe for the weekend' fund...

Okay, the web site update is coming, but it's just not quite here yet. In the meanwhile, just contact us at magsmoke@gmail.com The boards are $16 each + shipping (1 or 2 = $3.50 US/Canada, $4.50 EU/UK/Aus; 3 or 4 = $5.50 US/Canada, $6.50 EU/UK/Aus). For payment, we take PayPal at magsmoke@gmail.com We also stock the 2K tempcos if you need them. Thanks!

BTW, just got the prototype boards for the Thomas Henry Super LFO (from the AS21C book). Hopefully I'll test it tonight or tomorrow and let eveybody know how it goes.


Tim (soldering like mad) Servo

[philpeery]

Tim,

Cool! Now that I know the secret handshake.....
Sending an email for a few 566 boards shortly! Can wait for the LFO, that's one I'd love to have too!

Phil

[Danno Gee Ray]

Any news on the Super LFO?

[espressogeek]

Can someone point me to where I can purchase a quantity of the LM566's at a reasonable price? I tried arcadechips but paypal said they were unable to receive money at this time.

[Appliancide*]

Check the bay. 10 packs of the cans for $40 and single dips for $9 a piece.

[krisp14u]

I haven’t that many left to sell but at 2.50 each that’s less than $4 US each at today’s prices + shipping from the UK

drop me a PM

[vtl5c3]

Is it possible to get a block diagram of this VCO? I'm not 100% clear on all of its features.

[Tim Servo]

[vtl5c3]

Hi Tim,

Thank you for the diagram! Aside from the noise source, this VCO has almost the same feature set as Tom's CEM3340 based Deluxe VCO. Very nice!

Romeo

[Sound]

Well Im coocking the Sheboygan

I have mounted the noise source in a breadboard and I noticed the crosstalk with a VCS (working like oscillator) that I had connected in the power supply.

I noticed that instead connect the Base of the transistor Q3 (the source of the noise) to -15V If you connect it to Ground it gives you noise,
but you dont have crosstalk.

I dont know why.

Regards.

[Tim Servo]

Hey Sound,

From what I understand, transistor noise sources like the one found on the TH-101 work by putting a fairly large reverse biased voltage across a transistor. The current design has 30V across the noise transistor, but it could very well be that 15V works almost as well. My guess is that the noise may be reduced in level slightly (accounting for the difference you hear), but that this avoids the interference with the -V rail. According to Dave Brown, who did a lot of detective work on this, the noise bleeding into the -V rail is what causes the crosstalk, and it could be that you've discovered a very simple solution for this. Dave also has a relatively simple fix involving a zener and a few components to better isolate the -V supply at the noise tranny. I've never fixed the crosstalk as I don't use the noise source by itself, and I wanted to keep the design of the board as close to the 566 Book schematics as possible (and I'll admit that I really like the "grit" that adding a teeny bit of noise mod adds to the sound). Thanks for the tip, and I'll check it out on my TH-101.

Tim (Mr. Teeny Bit of Noise) Servo

[Sound]

Hi Tim, the noise output seems the same: About 10V peak to peak both and 1.7VRMS both. Connecting the base of Q3 to -15 as well to Ground.
I m testing the 566 noise source in a breadboard and listening the crosstalk from a oscillator connected in the same power supply.
It is curious, if you remove the transistor, the noise stops, but you can hear the crosstalk from the oscillator. And you can hear the crosstalk connecting R9 to plus or to minus. Removing R9 the cross talk stops, as well grounding within R9 and C5.

The truth is if there is no intention of put the extra noise output this issue is not relevant. And maybe is better due that there is a little amount of self modulation?.

Only for curiosity I will try this on the pcb, seems very easy , just don't soldering the base of Q3 to the PCB, and soldering a cable in its leg to the ground leg of C8 or C15, in the components PCB side. I will post the results.
Also, if you want to solder the Q3 at the PCB, you can cut the trace that goes to the -15 and connect the base to Ground that is in all the PCB.
Although that if finally I don't put a noise output I will leave the PCB like it is. And this bring me to a new questions...

I'm considering to make a front panel like David Brown did: http://modularsynthesis.com/magicsmoke/566/566.htm (amazing site David). So, it is that noise is normalized to one of the FM input jacks in order to save front panel.
But looking at the schematics, I noticed that the internal resistor that brings the noise to the CV summer is R17 and its value is 10K. The noise level before R17 is 10V peak to peak. So if i bring this level noise to the 100k R104 ej, Seems that I will lose noise modulation amplitude.

So my question is: Do I need a 20V peak to peak noise signal for achieve the same modulation amplitude if I pass it through a 100k resistor instead the 10Vpk to pk through 10K resistor?

[davebr]

[Sound]

Yes! seems very astute solution. Thanks Dave. I'll try it.

[Sound]

oeoeoeoeoeoeoe oeoeoeoe oeoeoe

I just calibrated it. Its working. oeoeoeoeoe! Other enriching experience!

Finaly I add the noise attenuator like the original design. Also I added four noise outputs in order to fit the panel, these come from the noise generator of one VCO with the base transistor grounded and they are buffered, with 4 opams like enveloper followers. The other noise generator from the other VCO is like the original design, with the transistor base to negative rail.

The VCO fed with the original noise generator, I mean with the transistor base to negative rail, has a more "aggressive" and "unfriendly" sound when you modulate the VCO with it. I like it much more. The other is like more "clean".

And this is:

[Tim Servo]

Dang, NICE work Sound!!

That really looks fantastic. I'll bet you're the only person around with a Dual Sheboygan!

Also, I agree about the noise source - the "stock" version (without any noise crosstalk mods) has a more agressive sound to the noise mod, which I prefer. Again, that's some very nice panel work there. Don't forget to share some samples with us if you make any wacky noises.

Tim (owner of a triple Mankato) Servo

[Sound]

Thanks Tim, the Oscillator is awesome, and seems a very good friend of the klee sequencer, I mean three buses to square, square/2 and square/4 kind of arpegios.
This is a monster of the unfriendly and cracked sounds, with its noise modulation and sync.
Oh man! I will ll sample it.