Fonik LPG: modifying it ( with more CV inputs and others )

Funky40 · Last edited by Funky40 on Wed Apr 02, 2008 3:04 pm; edited 1 time in total

hi, i need some help to modify the Fonik LPG.

how can i make more CV inputs ?
The regular CV input has not only an input Resistor,
it has also a crossconnection to the Offsetpot with a Resistor and a cap. ( R4 , C5 )
so i think it is not enough to just add another CV input with a inputresistor.

the schematic: ( side 2 )
http://modular.fonik.de/pdf/low%20pass%20gate.pdf

i have a dual Fonik LPG running, and i'm often miss more CV inputs.
got now new boards and like to modify it with some cludging

fonik · Posted: Mon Mar 31, 2008 1:06 am Post subject:

if i ever would built one again i'd tried to leave off R5, C5. as you can see from the redrawn schematics i just did a layout for p grenaders version of this LPG. in fact i don't know what R5, C5 is actually used for... any idea anyone?

Posted Image, might have been reduced in size. Click Image to view fullscreen.

Posted Image, might have been reduced in size. Click Image to view fullscreen.

Funky40 · Posted: Mon Mar 31, 2008 4:14 am Post subject:

good Info fonik ! thanks !
so i will try just to sum another input with input resistor

a.b.o.z. · Posted: Mon Mar 31, 2008 5:26 am Post subject:

what is low pass gate and what does it do?

sneakthief · Joined: Jul 24, 2006 Posts: 569 Location: Berlin

fonik - did you ever try the resonance option?

a.b.o.z. - it's the vactrol-based filter/gate that gives the buchla it's infamous plucked / "banjo sounds" Very Happy

more info & samples:

http://www.cyndustries.com/modules_quadgate.cfm
http://www.doepfer.de/a1012.htm

fonik · Posted: Mon Mar 31, 2008 11:11 pm Post subject:

loss1234 · Posted: Tue Apr 01, 2008 4:13 am Post subject:

im confused
it looks like your old docs have 2 vactrols in the schematic, while the new doc has only one.

which one is correct? or am i reading this wrong

thanks

sneakthief · Joined: Jul 24, 2006 Posts: 569 Location: Berlin

thanks fonik - i thought so.

loss1234 - yes, you're reading it wrong. schematics often "visually" split up the single vactrol into individual LED and resistor components.

loss1234 · Posted: Tue Apr 01, 2008 4:43 am Post subject:

no i am pretty sure the old schematic shows two-i think i figured out the difference though. the old one shows two vclt5's and the new one shows one vtcl3/5

thanks

sneakthief · Joined: Jul 24, 2006 Posts: 569 Location: Berlin

oh the "old" schematic - yes, you're right: it does show V1 & V2 as an ersatz vtl5c3/2

fonik · Posted: Tue Apr 01, 2008 4:50 am Post subject:

one VTL5C3/2 instead of two VTL5C3 is much more economic...

Funky40 · Posted: Tue Apr 01, 2008 11:15 am Post subject:

I gonna build one LPG for a Friend ( ACA ), he is running it at 12V .
Does i have to change something ? ( i build again the old one )

I assume that it will have less Gain on 12V, whats not so good as it anyway has not too much
i don't know whats to change.

btw.:
i built my (old) Fonik LPGs also with the dual Vactrol VTL5C3/2
Fonik has made a wiring diagramm

krisp14u · Joined: Nov 11, 2006 Posts: 206 Location: uk

fonik · Posted: Wed Apr 02, 2008 12:54 am Post subject:

Funky40 · Posted: Tue Apr 08, 2008 11:00 am Post subject:

here is the schematic fonik has drawn,
which shows how to put one dual Vactrrol ( VTL3C3/2 ) into the old version of the fonik LPG

Posted Image, might have been reduced in size. Click Image to view fullscreen.

Funky40 · Posted: Wed May 28, 2008 5:22 am Post subject:

fonik · Posted: Wed May 28, 2008 5:28 am Post subject:

Funky40 · Posted: Wed May 28, 2008 5:36 am Post subject:

hmmm, i don't understand trimmers Embarassed

what Value should i solder in ?

fonik · Posted: Wed May 28, 2008 5:59 am Post subject:

Funky40 · Posted: Wed May 28, 2008 10:35 am Post subject:

ok, i will test it out.

I have a board here which can take also a Trimmer for R14.
The Board is allready populated, exept R14.
I'm just waiting for some stuff to make Faceplates.

thanks alot !
the Fonik LPG is allways the most important module in my System for my sound.

Funky40 · Posted: Fri May 30, 2008 2:29 am Post subject:

fonik · Posted: Fri May 30, 2008 2:34 am Post subject:

Funky40 · Posted: Fri May 30, 2008 7:43 am Post subject:

Ok, thanks

CJ Miller · Joined: Jan 07, 2007 Posts: 368 Location: 127.0.0.1

Regarding the choice of 2x single vactrol vs 1x dual vactrol - I read on the SDIY list a post from Peter Grenader who said that he by far prefers using two singles. Dual for VCA type use and reduced noise, but two singles for filtering and plucked sounds. He said he's built hundreds of these circuits and tinkered with them quite a bit over the years, so I trust his opinion here.

Meanwhile, my beautiful LPG boards are lost in the basement here! I have been looking for them for weeks. When my Klee boards arrived I collected them and my LPG together and decided to put them in some special place so nothing would happen to them. Now only if I could remember where!

Funky40 · Posted: Sat Jun 07, 2008 8:21 pm Post subject: