Eagle Files - VCO, Filters, Touch, and SeqSw

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AlanP
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Eagle Files - VCO, Filters, Touch, and SeqSw

Post by AlanP » Sat Oct 17, 2020 10:31 pm

No commercial use! Don't PM or email me for help (you can ask in this thread, but don't expect miracles.)

'Arpad Touch' is a PCB layout (including panel) for the Synapse touch controller schematic.

'korg34 ms10' has two PCBs -- one is a small board to replace the KORG35 module (thank you to Crazy Patroche for this), and a V/Hz based MS10 VCF to run it on. The audio input needs work done on it, seriously loud and touchy.

buchla291 is a layout for the Buchla 291 Bandpass VCF, with mods from Scott Stite to include LP and HP as well. One of the few filters to include a 'Bandwidth' control... it does need four VTL5C3 vactrols, however.

buchla 258 is a layout for the Buchla 258 Dual Oscillator. Version 0.1 uses the THAT340 transistor array, while Version 0.2 uses BCM857 and BCM847 (the dual-transistor type, not the single transistor type.) 0.2 is harder to solder, but 0.1 uses spendier parts. Be VERY careful when selecting the FET for the waveshaper part of this circuit.

seqsw962 is a three stage sequential switch, modelled after the Moog 962, except that this one is bi-directional and can handle bigger signals.
Attachments
arpad touch.zip
(43.86 KiB) Downloaded 104 times
korg35 ms10.zip
(58.34 KiB) Downloaded 67 times
buchla291.zip
(57.26 KiB) Downloaded 99 times
buchla 258.zip
(129.15 KiB) Downloaded 124 times
seqsw962.zip
(62.23 KiB) Downloaded 70 times

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HighLordFixer
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Re: Eagle Files - VCO, Filters, Touch, and SeqSw

Post by HighLordFixer » Sat Oct 17, 2020 11:00 pm

Thank you so much for posting these Eagle files!

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Re: Eagle Files - VCO, Filters, Touch, and SeqSw

Post by vladosh » Sun Oct 18, 2020 3:48 pm

Thanks for sharing these Alan :)

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Re: Eagle Files - VCO, Filters, Touch, and SeqSw

Post by Ayab » Mon Oct 19, 2020 1:34 am

AlanP - Thank you your designs are beautifully laid out.

Haven't heard of the synapse touch controller but sounds interesting,

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Re: Eagle Files - VCO, Filters, Touch, and SeqSw

Post by julios » Mon Oct 19, 2020 8:52 am

Nice work!
About the vco, is it running até +/-12?

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Re: Eagle Files - VCO, Filters, Touch, and SeqSw

Post by AlanP » Mon Oct 19, 2020 9:00 am

Yep, +/- 12V for all the modules.

On the 258, for 0.1 you need a through-hole jfet (selected for sine shaping), for 0.2 you can use either a through hole, or try your luck with a MMBFJ201 or MMBF5457. (Don't use both SMD *and* TH on the same side, the two footprints are electrically paralleled.)

The absolute worst one to actually solder is the KORG35 module -- it is a small PCB, and some of the parts on it are tiniest damn things I've ever soldered in my life. I strongly suggest anchoring the board you're working on to something solid, like a spare metal enclosure, and hitting it with a hot air rework station when done.

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Re: Eagle Files - VCO, Filters, Touch, and SeqSw

Post by julios » Mon Oct 19, 2020 9:08 am

Thanks!
One more thing, how many usefull octaves with the BCM857/4? Should i go straight for the That3340 for a more acurate tuning?

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Re: Eagle Files - VCO, Filters, Touch, and SeqSw

Post by Bamboombaps » Mon Oct 19, 2020 11:46 am

thank you, im looking to put together a euro buchla like system, this will help loads

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Re: Eagle Files - VCO, Filters, Touch, and SeqSw

Post by AlanP » Mon Oct 19, 2020 6:06 pm

I'm not sure on the octaves thing, I still have to do some (read: any) measurements on their accuracy. (If I want accuracy, I use Braids.) But the BCM transistors are a pig to solder, compared to the THAT, and the THAT is placed so that you can solder the tempco resistor on top, if you want.

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Re: Eagle Files - VCO, Filters, Touch, and SeqSw

Post by Bamboombaps » Tue Oct 20, 2020 11:46 am

can i just check that the 258 main pcb 01 is compatible with the controls pcb 02?

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Re: Eagle Files - VCO, Filters, Touch, and SeqSw

Post by AlanP » Tue Oct 20, 2020 5:53 pm

It is, only difference for the control was that v0.1 of the control PCB had no power lines going to the TL072.

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Re: Eagle Files - VCO, Filters, Touch, and SeqSw

Post by Ayab » Wed Oct 21, 2020 8:00 am

Re: Touch -

A couple of questions:

- Can you please confirm the type of jack socket your footprint is for. If easier just post a picture.

- Does the panel need piezo discs soldered on?

Thank you again so much AlanP you rock!

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Re: Eagle Files - VCO, Filters, Touch, and SeqSw

Post by AlanP » Wed Oct 21, 2020 8:33 am

PJ301BM -- what I think of as 'Erthenvar Jacks'. The ones with metal wrapped around three sides. https://www.thonk.co.uk/shop/3-5mm-jacks/

You could possibly redesign it for thonkiconns. I have lots of both lying around.

No, no piezo discs -- the copper layer on the front of the panel acts as a capacitive pad, and the two 3 pin headers connect the capacitive touch pads to the rest of the circuit. (The touch panel MUST be made using normal FR4 PCB material, you cannot use aluminium when ordering!)

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Re: Eagle Files - VCO, Filters, Touch, and SeqSw

Post by Ayab » Wed Oct 21, 2020 12:35 pm

Thank you for the reply Alan P

Erthenvar jacks is fine - I can get some.

I suspected that it was just the capacitative touch pads. That is so amazingly excellent.

:hail: :hail: :yay: :sb:

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Re: Eagle Files - VCO, Filters, Touch, and SeqSw

Post by Ayab » Thu Oct 22, 2020 4:46 am

For anyone interested this is the original touch controller article by Arpad Benares (see AlanP's panel) from Synapse Magazine.
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Arpad Touch.gif

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Re: Eagle Files - VCO, Filters, Touch, and SeqSw

Post by Ayab » Sun Oct 25, 2020 9:47 am

I want to mod the Korg 35/MS10 VCF to configure as an HPF. Is similar but not the same as the MS20 VCF (where an HPF input can be added by switching jack inserted between the 1nf cap [C6 on Rene Schmidt version] and ground).

Assuming pin 7 of the K35 is equivalent to the MS20 Schematics OTA output maybe the HPF jack should be from the capacitor C6 also?

Little bit unsure as C6 to ground on the K35/MS10 is attached to the opamp inverting input (whereas on MS20 is the non-inverting opamp input)

Am sure this would be useful for others who wanted to build this early MS10 filter.

I'll get the boards made and then will test the mod out and hopefully will not damage anything.
Attachments
Korg MS Schematic HPF input.png
Rene Schmitz MS20 VCF with HP wiring.png
Rene Schmitz MS20 VCF with HP wiring.png (22.77 KiB) Viewed 567 times

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Re: Eagle Files - VCO, Filters, Touch, and SeqSw

Post by Ayab » Mon Nov 09, 2020 3:27 pm

I sent gerbers off to JLCPCB

Maybe because my version of Eagle (7.5.5) is bit old but I had some issues with the panels.

I ran the excellon drill thing to generate the gerber drill files.

Anyway the problem is that the gerbers didn't seem to show actual cutouts (i.e. holes) for the panel controls. Luckily they asked me about it.

Also they said there was no boundary for cutting out the outline of the panel so they used the silkscreen outline.

Hopefully it will be ok - difficult to know from a gerber viewer if a cutout is correctly indicated (I am a newb with gerbers).

The only queries they had was with the panels. So make sure you ask the fab house to cut out all the panel holes.

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Re: Eagle Files - VCO, Filters, Touch, and SeqSw

Post by AlanP » Mon Nov 09, 2020 11:07 pm

I use Seeedstudio's CAM file for generating 2-layer PCBs, with Eagle 7.5.0. All the holes above 3.2mm in diameter are in the Dimension layer, as is the board outline.

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Re: Eagle Files - VCO, Filters, Touch, and SeqSw

Post by Bamboombaps » Wed Nov 18, 2020 11:53 am

I have a couple spares of the buchla clones
DM if interested
IMG_20201118_163922.jpg
IMG_20201118_163854.jpg

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Re: Eagle Files - VCO, Filters, Touch, and SeqSw

Post by Ayab » Thu Nov 19, 2020 12:40 pm

Hi Alan P

Thanks for replying - I explained the cutouts to JLPCB and the result is fine. Think was glitch at their end and they were happy to sort it out.

I do have some questions on the Buchla 258 VCO:

1. There are some resistor values that I am having difficulty working out.
(R26, R25, R33, R34, R40, R72, R71, R79, R80, R86)

Mark Verbos’s schematic that you said on Electro-Music you used has values for these resistors in a table for Saw and Square. I can try and use his values but not sure getting the right ones. Would be great if you can help? (Btw does infinity mean no resistor as in no continuity?).

2. What values of the 9MM Pots worked for you?

3. What value are C4 & C16 Electrolytic caps on the Pots Board? Mark Verbos used 15uf on his schematic.
(Maybe helps to jog your memory that C4 is between the FM_IN jack/attenuator pot and the FM CV circuit. C16 is between the FM_IN B jack/attenuator pot and the B FM CV circuit.)

4. For the 2K thermistors would ppm 3300 or 3500 be better?

(5. You mentioned Polystyrene timing capacitors and I am not sure which ones these are. Can you confirm. **from your thread on E-M I note that this is the 4n7 "mica" caps**)

Sorry for all the questions but I have looked at it really carefully and thought better to try to ask in one go!

Thanks again for your kind contribution to the forum. I am really excited about building these.

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Re: Eagle Files - VCO, Filters, Touch, and SeqSw

Post by AlanP » Thu Nov 19, 2020 1:57 pm

1 - Infinity means omit the resistor entirely. I put in the values in my schematic to comply with Mark's table, and the result should match the panel. I included the omitted resistor locations in case someone wanted, say, a dual vco with ramp on both sides and no square.

2 - I used 100kB everywhere, except for the FM In pot, which from memory uses 50kA.

3 - 15uF. I ordered some low profile ones from RS, but they shouldn't be too hard to find on Mouser. Just make sure that the height of the cap is 10mm or less.

4 - not sure, I wound up just using a boring metal film in the 'ALT' resistor locations

5 - https://nz.rs-online.com/web/p/polystyr ... s/0116307/ These are the caps I used in my final build. Polystyrene caps have lower leakage than normal box caps, but you can probably get away with using almost anything.

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Re: Eagle Files - VCO, Filters, Touch, and SeqSw

Post by Ayab » Thu Nov 19, 2020 6:09 pm

Hi AlanP

That is really helpful, thank you!
Last edited by Ayab on Thu Nov 19, 2020 10:27 pm, edited 1 time in total.

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Re: Eagle Files - VCO, Filters, Touch, and SeqSw

Post by AlanP » Thu Nov 19, 2020 6:11 pm

Use the values from the 0.2 schem.

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Re: Eagle Files - VCO, Filters, Touch, and SeqSw

Post by Ayab » Thu Nov 19, 2020 6:52 pm

Oops missed your comment. Didn't notice that!

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Re: Eagle Files - VCO, Filters, Touch, and SeqSw

Post by skautkurt » Tue Nov 24, 2020 1:19 pm

Hi,
Want to build one of the 258s, how would I go about the calibration? Which parameter should be set first?
Thanks for publishing these schematics :)
Cheers

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