Elektor Formant Modular

I sourced my CA's from university, they had been there for years and used 
many times so I had to expect failures, we students don;t look after things 
that well.

Concentrate on getting a current in to the comparitor section, look to get 
15uA or there abouts this should kick it off. I would like you to test the 
voltages at IC5, I need to know what pins 4, 5 and 6 read. this is the 
section on mine that went wrong. On two VCO's.

For a first project you are doing well mate. Catch you soon
Kris


>From: ganesha <goaqihai@...>
>Reply-To: ElektorFormant@yahoogroups.com
>To: ElektorFormant@yahoogroups.com
>Subject: RE: [ElektorFormant] problem with formant pro vco (new design)
>Date: Sun, 9 Apr 2006 14:49:13 +0100 (BST)
>
>Hello Kris,
>I live in Belgium, My english is ok ( I hope ;-)) But
>I don't have much experience with electronics. This is
>my first project. I managed to build the powersupply
>and the tuningkeyboard (this is the small schematic
>with the 5 switches that produce 0v,1v,2v,3v and4v to
>act as a CV source to tune the VCO. =schematic 3.11 in
>the book) from the book and they both work.
>Btw, the R1 value I changed was for the
>tuningkeyboard, not for the vco. On the vco I've used
>everything like specified in the componentslist that
>is in the jpg at
>http://www.krinkel.be/formant/formantVCO.JPG
>
>I'll try to do the test what you describe. For the
>other questions:
>
>At the moment I'm only building 1 vco, but I plan to
>add some as soon as I get this one to work. I also
>want to build the vco of the ems VCS3etc. I also
>started the VCF but it is not finished yet.
>I bought the pcb + all the components from a guy in
>germany. When you say only 3 out of 5 CA3086 ic's
>worked, are you sure they got enought voltage? because
>one of the test in the book is to plug it in for
>20mins
>to let it warm up, and then at the collector from tr4
>you have to measure 1.6V to activate the CA3086. But I
>read on the internet someone who had to set it to2.4V
>before it worked so this could be what happened with
>the 2 non-working ic's you had. (I'm only guessing
>this offcourse)
>
>The cv comes from the schematic 3.11 in the book.
>
>I don't have skype yet but I'm sure I can install it
>by  thursday  so that would be great.
>
>Thanks!
>regards, Kris
>--- Kris Bishop <bishopkris40@...> wrote:
>
>
>---------------------------------
>I live in Scotland and have the strangest name,
>everyone asks where it is
>from. Can you imagine how strange this is lol
>
>Kris, First how good is your english
>second how good is your understanding of the
>electronics in this synth?
>
>
>I'm not that good and I managed this so here we go:
>
>First,
>
>Do not under any circumstances change any components
>unless you have read on
>the internet to do so. This is important as the VCO is
>based on a lot of
>electronic and electrical values that are dependant on
>each other.
>
>you were correct about r1 I have marked this as wrong
>in the book (cannot
>remember why??) but I am sure if you put the original
>value back in then we
>can work from here. (Next week I will open my synth
>and check my value, but
>moving house so please be patient)
>
>What you want with nothing other than a CV is for the
>current out of IC6 pin
>5 to double for every 1v change. This is the key to
>controlliing the synth.
>
>This said we can remove this device and insert a
>current, First you need to
>check what you are getting at pin 2 of IC 6. this is a
>voltage so is easy to
>test. make sure that you are getting something here,
>1v, 5v whatever. now if
>you can monitor the current from pin 5 of IC 6. what
>do you get and if you
>increase CV by 1V what do you get. (This section is
>only used to scale the
>input CV)
>
>ok so you get the correct operation from IC6 (CA3086)
>You must be using
>this. there is other methods but no for this circuit.
>
>no matter what happens if you get a current in to P7
>or input to IC2 then
>you should see Oscillations. I hope at this point like
>me everything is ok
>until now as this is where I had a problem. IC5 is a
>comparitor of sorts. we
>need the voltages to be different to get this circuit
>to work.
>
>Sorry but I'll come back to help in the next few days.
>But please did you
>get any sound at the start. also are you trying to
>build 1 or 2 VCO's??
>Where did you get your CA3086's from? I had 5 of these
>and only 3
>worked.....
>
>I did not carry out any tests from the book as I do
>not speak German but I
>did get good results after checking all components and
>soldering. Your
>circuit looks good but what does the other side look
>like? Mine is messy but
>works so don't worry. Where do you get your CV from.
>Sorry I need more info
>for the next step.
>
>If you want when I am at work I can talk to you on
>Skype if you'd prefer but
>I hope you speak english. We can even just use the
>chat by text option if
>you want but we can arrange a time. Probably Thursday
>or Friday night is
>best, I work night shifts then.
>
>Bishop (Kris)
>
>
> >From: ganesha <goaqihai@...>
> >Reply-To: ElektorFormant@yahoogroups.com
> >To: ElektorFormant@yahoogroups.com
> >CC: bishopkris40@...
> >Subject: RE: [ElektorFormant] problem with formant
>pro vco (new design)
> >Date: Sat, 8 Apr 2006 09:43:02 +0100 (BST)
> >
> >Hi Kris, ;-) feels like I'm writing something to
> >myself.
> >
> >
> >Thanks for your reply. I'll try to descibe the
> >different steps I did.
> >
> >In the beginning everything went fine, I've build the
> >eingangsspannungaddierers, exponentiators and
>heizung.
> >I plugged it in and after 20 minutes I have set the
> >voltage at kollektor tr 4 to 1.6V with trimmer
> >p8. So far no problem,I then continued building the
> >Sawtoothoscillator without soldering Tr3 so I could
> >meassure the current between kollektor tr3 and pin3
>of
> >ic2. I also made the abgleichskeyboard (I had to
> >replace R1 with 47K because otherwise my maximum for
> >switch 5 was 2.86 V instead of 4 V) and soldered the
> >pots for range and tune to the VCO pcb. I then tried
> >to messure the current that is supposed to be 0.002mA
> >but
> >nomather what switch I used on the abgleichskeyboard,
> >or to what position I turned the range and fine-tune
> >pots, I'm allways measuring 0,000mA. I thought
> >maybe I did not solder enough components on the pcb
> >because of the difference between the book and the
>new
> >design so I continued the entire pcb except for tr3.
> >But still no result. At the end as a last resort, I
> >also soldered tr3 in position but still no current.
> >Can you tell me what measurement I can do to track
>the
> >fault? On strange thing I allready noticed is that if
> >I meassure betweent the mass and before R5 (range) I
> >have 11.84V because I set the range pot fully open.
> >But after R5 (100K) I measure 0V. I suppose this is
> >not normal and that is the cause why turning the
>range
> >pot has no influence? So is the 100K to big?
> >Also would it be a problem that after the 7812 (ic7)
> >there is only 11.84V instead of 12V?
> >
> >I've uploaded a pic of the vco to
> >http://www.krinkel.be/formant/formantVCO.JPG
> >
> >best regards,
> >Kris
> >
> >
> >
> >---------------------------------
> >I'll reply here and on personal, as the group is here
> >so that people like us
> >can search problems first then ask.
> >
> >I'll help, but moving house so I can only promise you
> >an answer by Tuesday,
> >when I go back to work. What is the problem mate?
> >
> >Regards
> >Kris
> >
> >
> > >From: ganesha <goaqihai@...>
> > >Reply-To: ElektorFormant@yahoogroups.com
> > >To: ElektorFormant@yahoogroups.com
> > >CC: synth-diy@...
> > >Subject: [ElektorFormant] problem with formant pro
> >vco (new design)
> > >Date: Fri, 7 Apr 2006 23:25:54 +0100 (BST)
> > >
> > >Hi,
> > >
> > >I'm building the formant pro vco from the book of
> > >Hans-Joachim Helmstedt. But I'm having a problem
>that
> > >I cannot solve myself. Is there anyone who has
> >already
> > >built it and who would like to assist me?
> > >Please contact me off-list so I can send you a mail
> > >where I describe the problem.
> > >
> > >Thanks in advance!
> > >regards, Kris
> > >
> > >
> > >
> >
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