[sdiy] sync circuit woes

[Dan Snazelle]

FIXED IT

turned out i just needed to use an inverter.

not sure why (maybe due to interfacing cmos to +/-rails) but whatever...it works very well now!

now on to troubleshooting all 20 other portions!

when this things is all done i will be posting samples over at electro music .com and some block diagrams of how the thing works.




the only real issue (and its not too big of a deal) is some OVERLOADING in the mixer (audio summmer) circuit.

its just a typical 100k summer like you would see on a vco but with a 50k pot before each sum. it seems that with all the inputs being quite loud (except the clean guitar which seems quiet in comparison even though it has almost X10 of gain) when they all get past 5 there is some distortion that results.

is this typical of an opamp mixer? 

thanks so much

it really is almost done!

--------------------------------------------
check out various dan music at:

http://www.myspace.com/lossnyc  


http://www.soundclick.com/lossnyc.htm


http://www.indie911.com/dan-snazelle
(or for techno) http://www.myspace.com/snazelle 




> From: subjectivity at hotmail.com
> To: subjectivity at hotmail.com
> Subject: RE: [sdiy] sync circuit woes
> Date: Thu, 20 Nov 2008 13:08:46 +0000
> 
> 
> Ok
> 
> scratch that
> 
> I have narrowed down the problem more.
> 
> CMOS into a sync input. is there something i need to do to make this work?
> 
> When i connect a regular square wave (from say another vco) the sync  works fine. BUT (the main reason i wanted SYNC) i am using a guitar through a high gain amp into a divider section into my sync. It worked on breadboard but now (maybe because i added a diode before the input of the divider board) it isnt.
> 
> So could the problem be that the divider board output is only on + 15 and gnd and the rest of the circuits are on +15 and -15?
> 
> and if so, how could i remedy this? an inverter? a diode?
> 
> 
> at least my sync kind of works now!
> 
> seriously though, i am trying to figure out if i should put a diode on the dividerboard out (this is where the squared guitar comes from) or if this is going to be more complicated. it is a high volume signal and it is squared up very nicely. so thats why i started thinking its got the wrong swing.
> 
> thanks
> 
> 
> 
> --------------------------------------------
> check out various dan music at:
> 
> http://www.myspace.com/lossnyc  
> 
> 
> http://www.soundclick.com/lossnyc.htm
> 
> 
> http://www.indie911.com/dan-snazelle
> (or for techno) http://www.myspace.com/snazelle 
> 
> 
> 
> 
>> From: subjectivity at hotmail.com
>> To: synth-diy at dropmix.xs4all.nl
>> Date: Thu, 20 Nov 2008 12:46:29 +0000
>> Subject: [sdiy] sync circuit woes
>> 
>> 
>> working with the sync circuit that is HERE (on 2 pages)
>> 
>> 
>> http://www.elby-designs.com/asm-2/vco/vco1-summer-asm2-cct.pdf
>> http://www.elby-designs.com/asm-2/vco/vco1-cco-asm2-cct.pdf
>> 
>> 
>> I am getting the sync signal coming IN to the input. i am getting that into pin 3 of the Tl081/71
>> 
>> the resistors are getting gnd and -15v
>> 
>> i need to figure out how to test from that point on. (pin 6 and on)
>> 
>> since the output of that first opamp is a comparator, i cant check for sound. can i check for something on a scope?
>> or a DVM?
>> 
>> I had to fix the VCO to work with a 10pf timing cap instead of an 18pf..it wouldnt work without that change....could that make a difference? maybe i need to change some values?
>> 
>> are there any common issues with sync circuits i could be on the lookout for?
>> 
>> 
>> i will start checking for cold solder joints.
>> 
>> i really appreciate it
>> 
>> 
>> THANKS!!!
>> 
>> 
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