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 Forum index » DIY Hardware and Software » The layout factory
APC BUILD Help
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Project_2501



Joined: Jan 31, 2018
Posts: 35
Location: Los Angeles

PostPosted: Mon Feb 05, 2018 6:57 pm    Post subject:  APC BUILD Help
Subject description: Need some advice
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Hello everyone Smile

Just got into soldering and drooling over schematics just weeks ago.

Need some love.

I only have a small sawtooth oscillator working at the moment with a 2n3904 transitor from Lookmumnocomputer, but I'm hungry for more.

Does anyone have a simple layout for an APC, or help understanding layouts google to get my feet more wet.

https://paulinthelab.blogspot.com/2014/02/atari-punk-console-stripboard-veroboard.html

This layout looks fun but vr2-3,3 means what for the pots????? I know the middle leg on a pot is the swiper or (2) but vr??? I don't have a clue to finish the wiring. I did solder together an layout of an APC but I messed up and the source of that layout is meh.

Also, after this, I know I will want more, cause we all do. Does anyone have any recommendations for a VCO this is generally simple and a vcf to get my feet wet. I'm very new to layouts and schematics. At the moment I can only build off a stripboard layout. I'm planning to build a Baby 8 to try everything together for music from outer space... Don't worry I have Ray's book on my night stand.
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PHOBoS



Joined: Jan 14, 2010
Posts: 4032
Location: Moon Base
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PostPosted: Mon Feb 05, 2018 7:17 pm    Post subject: Reply with quote  Mark this post and the followings unread

welcome party!

VR probably stands for Variable Resistor and the numbers are the connections [1,2,3 where 2 is wiper, 1,3 are the two outer connections].
There seems to be an error though: VR1-3 should be VR1-1 and VR2-3 should be VR2-1.

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Grumble



Joined: Nov 23, 2015
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PostPosted: Tue Feb 06, 2018 12:14 am    Post subject: Reply with quote  Mark this post and the followings unread

And one more error: out should be VR4-2
Oh and the components names don't match:
VR1 = R2, VR2 = R3, VR3 = R4
C3 is backwards Rolling Eyes

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Project_2501



Joined: Jan 31, 2018
Posts: 35
Location: Los Angeles

PostPosted: Wed Feb 07, 2018 7:08 pm    Post subject: Reply with quote  Mark this post and the followings unread

Oh, I see where some of my confusion is coming from. This design has 3 Potentiometers, 2 for the sound, the other for volume. Can I ignore the the 3rd pot for volume to save parts? I only have (2) 500k's on hand for the build.

How the potentiometers are lined is the only thing stopping me from firing off some sound.

Just to clarify, rows (a,b,c,f,g) are where the leads are going from and to the pots? Is there a simpler way to say how to wire all the pots. I'm lost here :/
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Ayab



Joined: Oct 27, 2015
Posts: 108
Location: London, UK

PostPosted: Thu Feb 08, 2018 8:56 am    Post subject: Reply with quote  Mark this post and the followings unread

I was confused to start with but it will all make sense soon. Don't worry it is normal to take a little time to understand!

The stripboard drawing you posted just has a,b,c,d,e, etc.. down the side and numbers at the top just as a reference to help you place components on your own stripboard. For instance (yes) you can replace the volume pot with a wire or better a fixed resistor if you have any (say 100K) between I1 and J1.

Pot wiring will be easy if you rename the stripboard picture according to the advice given by Phobos and Grumble. They have compared the schematic diagram (usually accurate) with the stripboard picture and advised you accordingly. Those guys know their stuff and design and build their own original sound circuits so you are really lucky that they are helping you!!

First rename so that the stripboard and the schematic are the same:

"VR1 = R2, VR2 = R3, VR3 = R4"

Then the changes, first "VR1-3 should be VR1-1" = so that is R2-3 should be R2-1 = so just swap the outer connection on R2 keep the wiper the same

Next: "VR2-3 should be VR2-1"

"Out should be VR4-2"

"C3 is backwards" = look at the schematic the plus sign on the capacitor symbol is on the half before the chip (going to IC2 pin 3). The stripboard C3 has a greyed out top half denoting the positive (easy to remember that the long leg, as with led's, is positive) and that is wrong it should be the other way round.

Have a read about pots being set up as either voltage dividers or variable resistors to understand them better. MFOS is a good website for beginner explanations.

post if you need some help (i am not on here every day but should see it soon or someone will help)
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PHOBoS



Joined: Jan 14, 2010
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PostPosted: Thu Feb 08, 2018 9:44 am    Post subject: Reply with quote  Mark this post and the followings unread

Ayab wrote:
"C3 is backwards" = look at the schematic the plus sign on the capacitor symbol is on the half before the chip (going to IC2 pin 3). The stripboard C3 has a greyed out top half denoting the positive (easy to remember that the long leg, as with led's, is positive) and that is wrong it should be the other way round.

I am probably going to make things more confusing but I am pretty sure the capacitor is backwards in both the schematic and
the stripboard layout. The greyed area is most likely the negative side as this is usually (but definitely not always) marked on
the capacitor. But looking at the circuit diagram the side that is connected to GND (by R4/VR3) should be the negative side. So
although I think the stripboard layout corresponds with the circuit diagram it is backwards.

Quote:
Have a read about pots being set up as either voltage dividers or variable resistors to understand them better. MFOS is a good website for beginner explanations.

+1 for MFOS. There is a ton of useful information on there and the way things are explained and drawn it is indeed great for
beginners. (thanks Ray!) Also try to understand why the parts are placed on the stripboard the way they are by comparing it
with the circuit diagram. Being able to read circuit diagrams is one of the most important things for DIY electronics.

There is also another APC thread here which might have some useful info.

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Ayab



Joined: Oct 27, 2015
Posts: 108
Location: London, UK

PostPosted: Thu Feb 08, 2018 9:57 am    Post subject: Reply with quote  Mark this post and the followings unread

Hi PHOBoS - Oops! That's why help from guys like you is great! Yes MFOS is great, RIP Ray (looks like I should do some more reading there too!!)

That is alot of mistakes for such a small circuit!

Project-2501 - (love the name am a Ghost in the Shell fan too - anime one being the best!!) best to make sure layouts have been verified as built and working.

Last edited by Ayab on Thu Feb 08, 2018 11:31 am; edited 2 times in total
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PHOBoS



Joined: Jan 14, 2010
Posts: 4032
Location: Moon Base
Audio files: 590

PostPosted: Thu Feb 08, 2018 10:54 am    Post subject: Re: APC BUILD Help
Subject description: Need some advice
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Hi Ayab Very Happy
We are all here to help eachother and it always gives me great joy when I see that happening. It's one of the reasons why I love this place.
(I hadn't made the connection with Ghost in the Shell but yeah that's definitely one of the better animes)

Project_2501 wrote:
Also, after this, I know I will want more, cause we all do. Does anyone have any recommendations for a VCO this is generally simple and a vcf to get my feet wet. I'm very new to layouts and schematics. At the moment I can only build off a stripboard layout.

Have a look at the circuits by Nicolas. They are pretty simple, often run of a single supply and have a stripboard layout.

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"My perf, it's full of holes!"
http://phobos.000space.com/
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Ayab



Joined: Oct 27, 2015
Posts: 108
Location: London, UK

PostPosted: Thu Feb 08, 2018 12:57 pm    Post subject: Reply with quote  Mark this post and the followings unread

Hi PHOBoS - Very Happy

+1 on Nicolas circuits

I just got hold of an unused betamax video tape (in the packaging!) to build the ribbon controller.
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Project_2501



Joined: Jan 31, 2018
Posts: 35
Location: Los Angeles

PostPosted: Thu Feb 08, 2018 3:45 pm    Post subject: Reply with quote  Mark this post and the followings unread

[quote="PHOBoS"]
Ayab wrote:

There is also another APC thread here which might have some useful info.


Ironically, this is the original schematic I used for my first mock up, as in I just solder it hoping for glory, but silly me cut the middle trace between the 555's. OPPS! hmmm maybe can I solder a jumper to fix my mistake. Gonna try that first.

I was kinda hoping someone would catch my reference to Ghost In The Shell. Funny thing, GITS got me into the modular synth world. Something about the GITS and the music I have found due to GITS got me into exploring sounds. I'm a jazz trombonist, but something about circuits caught my eye, so here I am.

Gonna give this schematic a go tomorrow Smile and not cut the trace in the middle Razz
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Ayab



Joined: Oct 27, 2015
Posts: 108
Location: London, UK

PostPosted: Fri Feb 09, 2018 2:14 am    Post subject: Reply with quote  Mark this post and the followings unread

Hi Project 2501 - There is some cool "Appleseed" anime too Smile

I regularly listen to John Coltrane and Miles Davis and such but don't know much about jazz especially good newer stuff. Did go to a Snarky Puppy gig not long ago that was really good.

Back to the APC - Soldering a jumper will work to join where you cut the tracks. C3 should be the way PHOBoS points out (and the C3 strip board symbol indicates the negative short leg in grey) Embarassed

Btw if you only have linear potentiometers "B" you can convert them into pretty ok logarithmic "A" if you put a fixed resistor between the wiper and the pot leg going to ground (in the APC volume control R4 {VR3}, ground is leg 1) This is when the pot is acting as a variable resistor. The fixed resistor should be approx 20% (10-20%) of the value of the pot.

I have picked up a few other tips here such as you can add resistors in series to get a higher value (solder one end together and treat as one resistor in the same space).

Lastly here is a link to the Nicolas circuits suggested by PHOBoS. They are efficient and tried and tested.

http://electro-music.com/forum/topic-34550.html

The Nicolas circuits are v/Hz which is the same voltage control system as early Korg synths such as MS20. Many analog synths use v/oct (1volt per octave). The Nicolas circuits comprise all the necessary main modules for an excellent modular synth.

As a trombonist you may appreciate a ribbon controller. I must build mine!
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