Elektor Formant Modular

As my Formant was built pretty much as close to the manual as poss, 
the only way of triggering the ADSR's is via the keyboard. Always 
thought it strange that a gate input was not included on the front. 
As I want to get my panel design correct for any mods I may do.. I'd 
like to ask... how hard is it to add a gate in to the circuit? I can 
see where the keyboard attatches (via the weird little module that I 
dont know what it does) is there a suitable place to bring a wire to 
a jack on the front panel, so i can trigger from pulses, lfo's etc??

Cheers MArk...

PS:Despite the expense I decided to go with the Shaeffer method.. 
just seemed quick, simple, and high quality. finished the ADSR 
design, looks good. When I have finished and recieved the panels, 
Ill upload the Schaeffer files, so all can use if they wanna go that 
route?
PPS: Of course if someone has already used Shaeffer and has some 
files, then gimme gimme gimme!! Its a lot of work! Anyone got 
Shaeffer horror stories?.. Anyway now I'm making my usual mistake of 
posting too many Q's in one post. The SUB questions get answered and 
my MAIN query gets lost.. so reminder.. ADSR.. Trig in's?? Anyone? 
Buhler? Anyone?

Hi,

Depending on which circuit you have the modification should be very simple. 
On the original circuit there is a wire bridge on the PCB which is the 
largest to the right of D3. Simply using this junction would allow you to 
input a gate voltage from the front panel. However this would mean that the 
noraml input at the rear of the PCB will need to be removed.

Another option is to use a mono socket with a switch which I found to be the 
comon part you could buy anyway and I use them troughout. Now where to 
connect it is the issue. The circuit would be required to have the original 
Gate path interupted. This can be done by simply removing the previous 
bridge connection (Gate to R5) and then.....

Socket used!
_______  __(Output of socket)
|           |
|           |
------------  __(Internal input)
  |(Ground)

The existing wire connected to switch B should be cut and soldered to the 
output of socket this will allow any of the Gate voltages to flow into the 
switch so AD mode can still be selected. A second wire is required from this 
connection (Output). This will connect to the removed bridge, at the lower 
point that is connected to R5 (The one in line with D3) This is important as 
this is the actual gate input to the circuit.

Now to allow the Internal Gate to connect the Connection B of the PCB should 
be connected to the Internal input pin of the socket. Now normally the old 
gate voltage from the Keyboard will still work as it always has. But when an 
exrternal gate signal is plugged into the socket which will be mounted on 
the front panel the socket acts as a switch and only allows the external 
signal to flow giving an option of having a different gate control.

Hope this is what you were looking for.
Kris Bishop

>From: "markfrancombe" <mark@...>
>Reply-To: ElektorFormant@yahoogroups.com
>To: ElektorFormant@yahoogroups.com
>Subject: [ElektorFormant] ADSR gate In mod
>Date: Sun, 17 Apr 2005 13:33:23 -0000
>
>
>As my Formant was built pretty much as close to the manual as poss,
>the only way of triggering the ADSR's is via the keyboard. Always
>thought it strange that a gate input was not included on the front.
>As I want to get my panel design correct for any mods I may do.. I'd
>like to ask... how hard is it to add a gate in to the circuit? I can
>see where the keyboard attatches (via the weird little module that I
>dont know what it does) is there a suitable place to bring a wire to
>a jack on the front panel, so i can trigger from pulses, lfo's etc??
>
>Cheers MArk...
>
>PS:Despite the expense I decided to go with the Shaeffer method..
>just seemed quick, simple, and high quality. finished the ADSR
>design, looks good. When I have finished and recieved the panels,
>Ill upload the Schaeffer files, so all can use if they wanna go that
>route?
>PPS: Of course if someone has already used Shaeffer and has some
>files, then gimme gimme gimme!! Its a lot of work! Anyone got
>Shaeffer horror stories?.. Anyway now I'm making my usual mistake of
>posting too many Q's in one post. The SUB questions get answered and
>my MAIN query gets lost.. so reminder.. ADSR.. Trig in's?? Anyone?
>Buhler? Anyone?
>
>
>

Yeah... Schaeffer horror story. I had to pay them money. They sent the
panel in timely fashion and it was exactly what I ordered.  :^P

I'll look at the ADSR for you (if I can find the sch)

H^) harry

markfrancombe wrote:

>
> As my Formant was built pretty much as close to the manual as poss,
> the only way of triggering the ADSR's is via the keyboard. Always
> thought it strange that a gate input was not included on the front.
> As I want to get my panel design correct for any mods I may do.. I'd
> like to ask... how hard is it to add a gate in to the circuit? I can
> see where the keyboard attatches (via the weird little module that I
> dont know what it does) is there a suitable place to bring a wire to
> a jack on the front panel, so i can trigger from pulses, lfo's etc??
>
> Cheers MArk...
>
> PS:Despite the expense I decided to go with the Shaeffer method..
> just seemed quick, simple, and high quality. finished the ADSR
> design, looks good. When I have finished and recieved the panels,
> Ill upload the Schaeffer files, so all can use if they wanna go that
> route?
> PPS: Of course if someone has already used Shaeffer and has some
> files, then gimme gimme gimme!! Its a lot of work! Anyone got
> Shaeffer horror stories?.. Anyway now I'm making my usual mistake of
> posting too many Q's in one post. The SUB questions get answered and
> my MAIN query gets lost.. so reminder.. ADSR.. Trig in's?? Anyone?
> Buhler? Anyone?
>
>
>
>
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> Hope this is what you were looking for.
> Kris Bishop

Holey Moley.. It sure was Kris.. I dont know what all this means right 
now as my FORMANT is, as is, still in old crumbling box.. but when I 
start to take it apart I will sure as hell make this mod. I MAY just 
remove the keyboard totally, I dont use it at all.. so your 
suggestions were great!

I am assuming that FORMANT responds to standard modular trig voltages 
and CV's??? IE: I can fire the ADSR's from a oh.. I dont know.. MOTM 
analog seq? (not that I have one?

Save the hassle and look at the midijack from synhouse, I'm just building 
one just now with the midijack which means I can use any of my synths to 
control my Formant. Save buying and housing yet another keyboard.

I can help you with the connections of that too. Infact I will probably post 
my Report on building the synth in the next couple of weeks.

Kris

>From: "markfrancombe" <mark@...>
>Reply-To: ElektorFormant@yahoogroups.com
>To: ElektorFormant@yahoogroups.com
>Subject: [ElektorFormant] Re: ADSR gate In mod
>Date: Sun, 17 Apr 2005 15:17:58 -0000
>
>
> > Hope this is what you were looking for.
> > Kris Bishop
>
>Holey Moley.. It sure was Kris.. I dont know what all this means right
>now as my FORMANT is, as is, still in old crumbling box.. but when I
>start to take it apart I will sure as hell make this mod. I MAY just
>remove the keyboard totally, I dont use it at all.. so your
>suggestions were great!
>
>I am assuming that FORMANT responds to standard modular trig voltages
>and CV's??? IE: I can fire the ADSR's from a oh.. I dont know.. MOTM
>analog seq? (not that I have one?
>
>
>

Are there anyone here who knows where I can get a list of old Formant 
PCB numbers, and what they refer to?
I know that i.e. "EPS. 9723-1" is the PCB number for the Formant VCO.
But what about "EPS. 9949-1"? What is that?
Anyone?

-- 
tw.  :)

Hello everyone,
I have finally been able to continue building the (original) Formant 
VCOs again this summer.
These VCOs are build with original parts (uA726 and all), but with the 
updated Fet opamps (LF356H).

VCO #1 - everything works just fine!

VCO #2 - the core works (CCO, Exp conv., summing amp), and sawtooth and 
"spaced sawtooth" works fine.
However; the triangle (and hence the sinus) converter does not work as 
it should. It looks fine on the scope after the two diodes (the 
clipping part), but then something goes wrong, and all I get is a very 
weak (like 0.1V amplitude) semi-sawtooth. I have changed diodes, 
changed transitors, tripled-checked all components, solderjoints and 
connections. Putting in the optional cap (C13) does not change 
anything. It´s a fairly simple little circut, that triangle shaper, so 
there shouldn´t be much wrong. Any hints as to what I can do?

VCO #3 - the core does not work. Or start at all. Tomorrow I will try 
to put in the trimmer (P10) that was not needed because of the updated 
FET op-amp. It mentions in the text that inproper balance/level with 
the original FET transistors could lead to the VCO core not to start, 
hence the trimmer. However, this should be redundant with the new FET 
opamp. There could of course be something completely else that is 
wrong.
The summing amplifier for CVs (fine and course pots, offset trimmer, 
external CV etc.) seem to work.
The exponential converter seems to work.
All components gets the correct power (+15V, -15V, +5V, gnd)
I have used quality timer caps (polypropylene)
The transistor has been tested (I build the testing rig as explained in 
the book) to spec
Checked all components etc.

Any help appreciated.


Terje Winther
terje.winther@...
http://www.wintherstormer.no/