DIY Filter Question...

Keyboards, Synths, Samplers and Groove Boxes.

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Re: DIY Filter Question...

Postby gregwar » Thu Nov 15, 2012 1:14 am

here's the schematic and discussion of adding cv inputs to a 40106

there's some slightly more advanced uses of CMOS chips in synths like the edp wasp and dk synergy. here's the edp wasp's schematics.

for the dk synergy there's like 100 CMOS chips to make up the oscillators and such but those can be programmed into a PIC chip and take up considerably less space and cost.

PIC lunettas are an advanced project i might consider in the future when i have a better grasp of the basics.

here's the humble PIC synth which sort of gave me the idea of using PICs for this sort of thing. electric druid makes a sweet digital osc from a PIC chip

@metroid jurgen's wasp vcf clone is a sweet sounding and relatively simple project for a diy filter
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Re: DIY Filter Question...

Postby ElectricPuppy » Thu Nov 15, 2012 1:41 am

gregwar wrote:here's the schematic and discussion of adding cv inputs to a 40106


Ah. OK, see, I don't know everything. :lol: I see what they're doing there; The transistor across the cap drains the cap by more or less of a short across it. The amount of current it shorts is dependent on the voltage on the transistor's base.

That's gonna make like some seriously short pulses though, probably nearly inaudible. Which is fine if you're using the pulses as clocks for driving other things.
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Re: DIY Filter Question...

Postby ElectricPuppy » Thu Nov 15, 2012 7:57 am

Found this link in my bookmarks, you might find it interesting if you want to know more theory. http://www.allaboutcircuits.com/
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Re: DIY Filter Question...

Postby Plink Floyd » Thu Nov 15, 2012 10:39 am

ElectricPuppy wrote:
gregwar wrote:That's gonna make like some seriously short pulses though, probably nearly inaudible.
At the trigger out, yeah. It also has a "falling ramp" output, but I suspect it might not be "pretty" all the way through the freq range.

NERDS!
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Re: DIY Filter Question...

Postby gregwar » Sat Nov 17, 2012 4:12 am

here's a picture journal of building a modular in one month: http://experimentalistsanonymous.com/siam/journal.html

experimentalists anonymous also has a treasure trove of schematics and data sheets:
http://experimentalistsanonymous.com/di ... Schematics
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Re: DIY Filter Question...

Postby Veracohr » Fri Jan 11, 2013 8:03 pm

In case any DIY'ers are interested, I found something good a while back for PCB transfers. Don't mess around with trying to print on photo paper or anything like that.

These are plastic sheets, like old-school overhead projector sheets, with a blue coating on one side. You print on that side with a laser printer, iron on to the copper, then etch. Designed specifically for DIY PCB etching. I've found it to work pretty well.

Press-n-Peel Blue Transfer Film
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Re: DIY Filter Question...

Postby ElectricPuppy » Fri Jan 11, 2013 8:25 pm

I really, really, wanted that stuff to work. Photo etching has enough variables in it to make it kind of a touchy method for those once-in a-while uses. I bought some PnP Blue several years ago, and I just could NOT get it to cooperate. I don't know what I was doing wrong. It printed OK, but trying to transfer it to the board was fraught with problems.

Of course, the stuff I bought was years ago, maybe they've improved it.
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Re: DIY Filter Question...

Postby gregwar » Tue Jan 15, 2013 11:34 pm

i thought this was kind of cool

http://www.youtube.com/watch?v=utFhGX0X ... oBpT8pLTkg

*edit: can't remember how to poast utubz
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Re: DIY Filter Question...

Postby Plink Floyd » Wed Jan 16, 2013 5:23 am

Huh, that guy used a CNC mill to make his PCB. I guess that's one way, if you've one handy.

I hope to get started making a drum pad gizmo sometime in the next few months; I'll be trying the laser printer / FeCl3 method for the pcb.
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Re: DIY Filter Question...

Postby ElectricPuppy » Wed Jan 16, 2013 6:03 pm

Take photos, Plinky! I'd love to see progress shots.
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Re: DIY Filter Question...

Postby Veracohr » Wed Jan 16, 2013 11:17 pm

And for my next DIY suggestion:

Plink Floyd wrote:I'll be trying the laser printer / FeCl3 method for the pcb.


When I was looking up how to etch, I found this method:

http://www.instructables.com/id/Stop-us ... etter-etc/

I guess the general idea is that it's reusable and 'refreshable' by simply adding more acid and H202. It worked quite quickly the first time, after a few times it slows down. Next time I'll search for some way to heat it.
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Re: DIY Filter Question...

Postby ElectricPuppy » Wed Jan 16, 2013 11:29 pm

Veracohr wrote:Next time I'll search for some way to heat it.

Use a fish aquarium heater, the kind with a glass envelope.
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Re: DIY Filter Question...

Postby Plink Floyd » Thu Jan 17, 2013 4:48 am

Veracohr wrote:...CCiAHAS etchant...
Thanks! I've heard of that method, and I'd probably try it first if I didn't already have a quart of Brown on hand.

I think I might try this sponge trick:

http://www.instructables.com/id/Sponge-Ferric-Chloride-Method-Etch-Circuit-Bo/#intro

ElectricPuppy wrote:Take photos, Plinky! I'd love to see progress shots.
OK. But I thought you'd already done this?
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Re: DIY Filter Question...

Postby gregwar » Thu Jan 17, 2013 7:03 am

there's gotta be a way to just 3d print a whole synth

i'm just bitter as i took too long to activate my pre paid credit card an now ordering online is gonna be a pain. who has time for that shit ?

if i had a religion interest-charging credit cards would be illegal or whatevs

i could always get one of those debit cards that works like a credit card for online ordering but again it seems like jumping through hoops for the banks

fyi i didn't have a bank account until i was like 22, i just refused until i needed one for university. i would cash my paycheques at pawn shops and just use cash for everything.

as an anarchist i just think the finance/gov't behemoth are designed to suppress me
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Re: DIY Filter Question...

Postby Plink Floyd » Thu Jan 17, 2013 11:53 am

Gol Dangit.

But really, just get a card with no annual fee, preferably one that pays you 1% cash back, and never ever ever leave a balance on it.
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Re: DIY Filter Question...

Postby ElectricPuppy » Thu Jan 17, 2013 7:08 pm

Plink Floyd wrote:
Veracohr wrote:...CCiAHAS etchant...
Thanks! I've heard of that method, and I'd probably try it first if I didn't already have a quart of Brown on hand.

I think I might try this sponge trick:

http://www.instructables.com/id/Sponge-Ferric-Chloride-Method-Etch-Circuit-Bo/#intro

ElectricPuppy wrote:Take photos, Plinky! I'd love to see progress shots.
OK. But I thought you'd already done this?


Well, yeah, but I like to see how others get on with their projects. :thu:
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Re: DIY Filter Question...

Postby Plink Floyd » Thu Jan 17, 2013 10:32 pm

I Thank You!

and I Ask You: Any pcb tips? Like, what printer paper did you use, & did you use a clothes iron for the transfer, & stuff?
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Re: DIY Filter Question...

Postby ElectricPuppy » Thu Jan 17, 2013 11:02 pm

I haven't tried the transfer method with anything other than the PnP Blue. I've heard that you can print on glossy magazine paper and transfer that via a clothes iron, but I've never tried it. The other time I printed was directly on transparency for photo etching.

I suspect my failures with PnP blue are mostly related to the iron I was using. Not sure what, though.
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Re: DIY Filter Question...

Postby gregwar » Sun May 19, 2013 9:48 pm

I'm really digging these paper face Sergei :love:

Image

http://www.coa-modular.com/2012/06/03/w ... paperface/

there's been a few early 70s serge pcbs available from cat girl synth and some aluminum panels on muff but I'm thinking of making a paper face out of manga

would look cool with some lunettas
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Re: DIY Filter Question...

Postby gregwar » Fri Oct 11, 2013 10:43 pm

ElectricPuppy wrote:
gregwar wrote:here's the schematic and discussion of adding cv inputs to a 40106


Ah. OK, see, I don't know everything. :lol: I see what they're doing there; The transistor across the cap drains the cap by more or less of a short across it. The amount of current it shorts is dependent on the voltage on the transistor's base.

That's gonna make like some seriously short pulses though, probably nearly inaudible. Which is fine if you're using the pulses as clocks for driving other things.


what about the x-4060 osc ?

you feed an output into an input plus additional components and apparently you can make an osc that tracks pretty good :wat:

http://www.birthofasynth.com/Thomas_Hen ... -4046.html

can sum of u tech savvies have a look-see ?
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