Buchla 259 schematics HELP!

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Frekkia
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Buchla 259 schematics HELP!

Post by Frekkia » Thu Mar 26, 2020 4:40 pm

Hi guys I need a hand with the electronic schematics of the Buchla 259 Complex Waveform, I have circled the things I do not understand in the diagram, it is a bit of stuff I hope you can make me understand.
First page 1A:
1-red: I don't understand if it is a switch that changes I don't know in what, but I have a hypothesis that gives the + 5v regardless of how you change it.

2-Blue: I don't understand all those circles where they connect, maybe some have entered CV and I'm just not convinced.

3-yellow: what is the value of the r19C resistor? A, B is written.

4-purple: which diodes are they? all those not marked? there are not only these.

5-green: are they switches with a diode? if yes, what value is the diode?

Second page 2A:
1-violet: I don't understand if + 5v goes in the entries in the ic 13,8,9

2-red: do outputs 14, 15 have to be connected to something?

Page 3A:
1-red: +6 -6 where does it go?

2-green: index control current where is the input and output connected?
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tarandfeathers
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Re: Buchla 259 schematics HELP!

Post by tarandfeathers » Fri Mar 27, 2020 5:09 am

First page 1A:
1-red: I don't understand if it is a switch that changes I don't know in what, but I have a hypothesis that gives the + 5v regardless of how you change it.
This is the remote enable switch which determines whether the 259 will use the front panel controls, external computer control, or a combination of both. The output of the switch "EN A" is connected to all other points on the schematic labelled "EN A" and likewise for "EN B". In a schematic these are called net labels and they allow you to indicate that things should be connected without having to draw wires between them which can help to keep things clear.
2-Blue: I don't understand all those circles where they connect, maybe some have entered CV and I'm just not convinced.
These are connection points for CV coming from an external computer control system. Under normal circumstances they are not used for anything.
3-yellow: what is the value of the r19C resistor? A, B is written.
This is the trim pot. The value isn't super critical as it's just acting as a voltage divider, but 20k is typically used.
4-purple: which diodes are they? all those not marked? there are not only these.
Generic small signal silicon diodes. 1N457 or 1N4148 are fine.
5-green: are they switches with a diode? if yes, what value is the diode?
Yes, these are switches, and the diodes provide logic steering. Again, 1N457 or 1N4148 is fine.
Second page 2A:
1-violet: I don't understand if + 5v goes in the entries in the ic 13,8,9
The 5V generated by this amplifier is the power supply for these ICs, they are not powered from the 15V rail.
2-red: do outputs 14, 15 have to be connected to something?
No, these outputs are not used
Page 3A:
1-red: +6 -6 where does it go?
To the power supply pins of the CA3130 op amps - again, these are labeled +6 and -6
2-green: index control current where is the input and output connected?
The control current is generated by part of the circuit on page 4, and the LEDs of all vactrols used for modulation index must be conected in series. Again, this is kind of a net label.

If you're just learning to read schematics, Buchla is not a good place to start - lots of unlabelled parts, mistakes, etc. It would be better to look at circuits that are well documented to get a feel for things which will help you to intuit some of the missing information.
Dunnington Audio - Various Buchla accoutrements available

Frekkia
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Re: Buchla 259 schematics HELP!

Post by Frekkia » Fri Mar 27, 2020 7:44 am

Yes it is quite difficult, but the idea of building a Buchla on my own is something fantastic, and I know that I have other things to ask if it is not too much for you :mrgreen:

Page 2A:
1-red: how is resistance used? what does the phrase mean?

2-purple: what waveform is it? do you use it for something?

Page 3A:
blue: where should I connect output 8?

Page 4A:
yellow: I understand that the vactrol entries must go here, but there are two female entries. If I should connect vactrol in series I can only connect to one of the two females

and then I wanted to ask you the square output of the main oscillator where does it come out?

sorry for all these questions but I probably think they are not the last XD
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tarandfeathers
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Re: Buchla 259 schematics HELP!

Post by tarandfeathers » Sat Mar 28, 2020 7:03 am

Frekkia wrote:
Fri Mar 27, 2020 7:44 am
Page 2A:
1-red: how is resistance used? what does the phrase mean?
It means that if, once the module is built, the timbre circuit cannot be adjusted to work correctly, you can add this resistor to bring it into adjustment. You will need to select the specific value by testing it in circuit.
2-purple: what waveform is it? do you use it for something?
This is indicating that this point should be connected to the sine wave output from the principle oscillator.
Page 3A:
blue: where should I connect output 8?
It should be connected to the high/low range logic from the modulation oscillator
Page 4A:
yellow: I understand that the vactrol entries must go here, but there are two female entries. If I should connect vactrol in series I can only connect to one of the two females
I suppose you could call this a drawing error. Look at what the circuit does, think about how an LED works and connect the LEDs together in a string accordingly.
and then I wanted to ask you the square output of the main oscillator where does it come out?
I'm not entirely sure I understand your question?

What are you trying to achieve? Are you building a 259 using one of the several available PCB sets?
Dunnington Audio - Various Buchla accoutrements available

Frekkia
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Re: Buchla 259 schematics HELP!

Post by Frekkia » Sat Mar 28, 2020 11:57 am

tarandfeathers wrote:
Sat Mar 28, 2020 7:03 am
Frekkia wrote:
Fri Mar 27, 2020 7:44 am
Page 2A:
1-red: how is resistance used? what does the phrase mean?
It means that if, once the module is built, the timbre circuit cannot be adjusted to work correctly, you can add this resistor to bring it into adjustment. You will need to select the specific value by testing it in circuit.
2-purple: what waveform is it? do you use it for something?
This is indicating that this point should be connected to the sine wave output from the principle oscillator.
Page 3A:
blue: where should I connect output 8?
It should be connected to the high/low range logic from the modulation oscillator
Page 4A:
yellow: I understand that the vactrol entries must go here, but there are two female entries. If I should connect vactrol in series I can only connect to one of the two females
I suppose you could call this a drawing error. Look at what the circuit does, think about how an LED works and connect the LEDs together in a string accordingly.
and then I wanted to ask you the square output of the main oscillator where does it come out?
I'm not entirely sure I understand your question?

What are you trying to achieve? Are you building a 259 using one of the several available PCB sets?
I want to make a PCB for myself, and then adapt it to my Eurorack system.

I still don't understand very well where I have to connect the output 8 of ic4, do I have to connect it to the low hi tune switch?

By square wave I mean where do I find the final exit of principle oscillator? which is located on the module panel, because I only see the sine wave output and the triangle

tarandfeathers
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Re: Buchla 259 schematics HELP!

Post by tarandfeathers » Sun Mar 29, 2020 5:44 am

A few suggestions:

You will get more help with a project like this in the DIY section than in the Buchla/EMS/Serge subform.

If I was you, I would have a look at the Feedback Two59, it already does what you want:

https://feedback-modules.myshopify.com/ ... o-diy-kit1
https://feedback-modules.myshopify.com/ ... r-diy-kit1

No point in reinventing the wheel if your goal is not primarily to gain a deep understanding of the circuit design. The chances of making a properly working module based solely on the available schematics are very slim, and slimmer still if you are going to run it from a 12V power system rather than a 15V one. Even if you are determined to make your own PCBs for whatever reason, I would probably buy a set of Two59 boards as I believe these are known to work so they can serve as a reference to compare with the schematics. I should say however that I have neither built nor used any of the Feedback modules so do some research in the DIY subforum to see if there are any known issues.
Dunnington Audio - Various Buchla accoutrements available

Frekkia
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Re: Buchla 259 schematics HELP!

Post by Frekkia » Sun Mar 29, 2020 7:22 am

tarandfeathers wrote:
Sun Mar 29, 2020 5:44 am
A few suggestions:

You will get more help with a project like this in the DIY section than in the Buchla/EMS/Serge subform.

If I was you, I would have a look at the Feedback Two59, it already does what you want:

https://feedback-modules.myshopify.com/ ... o-diy-kit1
https://feedback-modules.myshopify.com/ ... r-diy-kit1

No point in reinventing the wheel if your goal is not primarily to gain a deep understanding of the circuit design. The chances of making a properly working module based solely on the available schematics are very slim, and slimmer still if you are going to run it from a 12V power system rather than a 15V one. Even if you are determined to make your own PCBs for whatever reason, I would probably buy a set of Two59 boards as I believe these are known to work so they can serve as a reference to compare with the schematics. I should say however that I have neither built nor used any of the Feedback modules so do some research in the DIY subforum to see if there are any known issues.
I believe that no module built to date Eurorack version has followed the original Buchla scheme, if not with modifications or removing something, I am not an expert in electronics but I am sure that the sound changes. From 12v to 15v, I think a boost lm2577 is enough, so as to have a PCB true to the original. I see that you understand the schematics, if it is not a problem for you give me a hand to understand the schematic, maybe even in private!

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shoegazer86
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Re: Buchla 259 schematics HELP!

Post by shoegazer86 » Sun Mar 29, 2020 12:31 pm

Frekkia wrote:
Sun Mar 29, 2020 7:22 am
I believe that no module built to date Eurorack version has followed the original Buchla scheme, if not with modifications or removing something, I am not an expert in electronics but I am sure that the sound changes. From 12v to 15v, I think a boost lm2577 is enough, so as to have a PCB true to the original. I see that you understand the schematics, if it is not a problem for you give me a hand to understand the schematic, maybe even in private!
Nobody has built a eurorack version to the original spec of the Buchla module mainly because there are numerous changes that will need to be implemented to work in a euro environment without patching workarounds. You wont be able to send any negative voltages to the CV inputs for starters, the output would have to be amplified to euro levels, and you'd have to attack the whole v/oct standard, so you'd already be limiting your patches around that module. In short, you won't be able to really make a fully functioning eurorack version without changing SOMETHING. It just wouldn't make much sense to shoehorn an entire 259 into eurorack without doing some heavy lifting in redesign, which tarandfeathers already pointed out. It's apples and oranges.

The Two59 has already been made with all of the logistics sorted on inputs and voltages, and it's groomed to work properly in a eurorack ecosystem.
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Frekkia
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Re: Buchla 259 schematics HELP!

Post by Frekkia » Sun Mar 29, 2020 5:23 pm

shoegazer86 wrote:
Sun Mar 29, 2020 12:31 pm
Frekkia wrote:
Sun Mar 29, 2020 7:22 am
I believe that no module built to date Eurorack version has followed the original Buchla scheme, if not with modifications or removing something, I am not an expert in electronics but I am sure that the sound changes. From 12v to 15v, I think a boost lm2577 is enough, so as to have a PCB true to the original. I see that you understand the schematics, if it is not a problem for you give me a hand to understand the schematic, maybe even in private!
Nobody has built a eurorack version to the original spec of the Buchla module mainly because there are numerous changes that will need to be implemented to work in a euro environment without patching workarounds. You wont be able to send any negative voltages to the CV inputs for starters, the output would have to be amplified to euro levels, and you'd have to attack the whole v/oct standard, so you'd already be limiting your patches around that module. In short, you won't be able to really make a fully functioning eurorack version without changing SOMETHING. It just wouldn't make much sense to shoehorn an entire 259 into eurorack without doing some heavy lifting in redesign, which tarandfeathers already pointed out. It's apples and oranges.

The Two59 has already been made with all of the logistics sorted on inputs and voltages, and it's groomed to work properly in a eurorack ecosystem.
Yes now I understand why nobody did it as I said, unfortunately I'm a beginner, one of the problems should be the 1.2v octave voltage for Buchla and Eurorack 1v, but I got an idea about this problem without change anything in the diagram, an op amp at the CV input of 259, which amplifies the 1v signal that arrives from Eurorack to 1.2v, could it work? should multiply going up octaves? that is 1v euro 1.2v buchla, 2v euro 2.4v buchla etc. it's right? there should also be problems with trigger and gate signals, with those I don't know what to do.

Frekkia
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Re: Buchla 259 schematics HELP!

Post by Frekkia » Wed Apr 01, 2020 7:33 am

I created a circuit that enters a signal of 1v the output and 1.2v, going up an octave always multiplies by 0.2% therefore 2v = 2.4v 3v = 3.6v etc .. and this I think works with regard to V/Oct Eurorack in Buchla

Then I made another circuit for the Buchla pulse, the buchla trigger should be of a time of 4ms at a voltage of 10v (this we can call it trigger), followed by a "ladder" of 5v until the input signal does not stop (keyboard notes)

not having a Buchla I don't know if it can work, what do you say? can go?
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tele_player
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Re: Buchla 259 schematics HELP!

Post by tele_player » Wed Apr 01, 2020 1:17 pm

Frekkia wrote:
Wed Apr 01, 2020 7:33 am
I created a circuit that enters a signal of 1v the output and 1.2v, going up an octave always multiplies by 0.2% therefore 2v = 2.4v 3v = 3.6v etc .. and this I think works with regard to V/Oct Eurorack in Buchla
You mean that a voltage gain of 1.2 will convert 1V/octave to 1.2v/octave. That’s 20%, not 0.2%.
Yes, that will definitely work.

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