That's the thing! When cycling it does produce around 5v. But when triggered externally it can get right up to 15v. But only with long fall times. Its like each successive trigger adds to the voltage when using long fall times.
--- In cgs_synth@yahoogroups.com, Richard Brewster <pugix@...> wrote:
>
> It is not functioning right if the output swings to +15V when cycling.
> Ken's notes:
>
> Adjustments on the VCS board are set to obtain a 0 to +5 volt level when
> the unit is cycling, producing a 100Hz triangle wave. An oscilloscope is
> required for this adjustment. In an oscilloscope is not available,
> adjust for the least distorted sounding waveshape.
>
> I guess that he means the single trimpot by "adjustments on the VCS
> board". I built two of these and did not have any problems.
>
> Richard Brewster
> http://pugix.com
>
> On 9/22/11 6:29 PM, scozbort wrote:
> > Cheers Laurie, I appreciate you input!
> >
> > Its the main OUT that gets hot. And I'm using a REV1.0 PCB so the 220k resistors should be correct. I thought about sticking a resistor on the output but that would affect the cycle out as well, which does not need attenuation.
> >
> > Its sounding more like its functioning perfectly. Am I being over-cautious worrying about throwing (potentially) 15V slopes around the system?
> >
> > - Kevin
> >
> >
> > --- In cgs_synth@yahoogroups.com, "Elby Designs"<elby_designs@> wrote:
> >> The END OUT output should be clamped to 5V because there is a zener diode in
> >> that line. If that is the output you are having problems with then the zener
> >> is either faulty, not fitted, or the wrong value.
> >> The OUT output doesn't have any such protection and it is feasible for the
> >> output to approach power rail levels as it is driven directly from the
> >> output of an opamp. I will need to study the front end more to determine if
> >> there is any internal clamping but it might be worth asking Ken what are the
> >> normal output levels to be expected. Maybe this output needs a simple
> >> resistor divider.
> >> The transistors are standard and should fit the pcb as is.
> >>
> >> The only other problem I can see is that Ken has 4 x 220K listed in his BOM
> >> and then says in the text that they should be 22K. I have supplied 220K
> >>
> >> Best Regards
> >> Laurie Biddulph
> >> Mobile: 0400 257 645
> >> Web: www.elby-designs.com
> >>
> >> -----Original Message-----
> >> From: cgs_synth@yahoogroups.com [mailto:cgs_synth@yahoogroups.com] On Behalf
> >> Of scozbort
> >> Sent: Friday, 23 September 2011 6:43 AM
> >> To: cgs_synth@yahoogroups.com
> >> Subject: [cgs_synth] Re: cgs75 hot voltage outputs
> >>
> >> OK here is some more info.
> >>
> >> Most people seem to have difficulty with the transistor pin-outs not
> >> matching the circuit. I don't think this is the problem here. The module
> >> functions perfectly (except for hot output), and the transistors were
> >> supplied in an Elby kit. I have emailed Laurie to see if the transistors he
> >> supplied are correct (can't seem to find a datasheet for them).
> >>
> >> Also the calibration trimmer does offset the hot output voltage, but no
> >> where near enough. I was wondering if a 20 turn trimmer here would allow me
> >> to drop the voltage of the output right down whilst still maintaining the
> >> correct triangular waveshape?
> >>
> >> Like I said it only outputs high voltages when its being triggered.
> >>
> >> It's completely useful as it is, I just have to attenuate the output. Not
> >> comfortable send 15v signals around the modular. Or do I not need to worry
> >> about this at all? I know it distorts my VCAs pretty quick.
> >>
> >> Any help much appreciated!
> >> - Kevin
> >>
> >> --- In cgs_synth@yahoogroups.com, "scozbort"<kevin.babbage@> wrote:
> >>> Hi!
> >>>
> >>> Can't believe I only just found this place...
> >>>
> >>> I'm having an issue with my VCS build and hoping someone has come across
> >> it before.
> >>> When I use the trigger in and slow fall times the module outputs very hot
> >> voltages - I think it would go to 15v if I let it.
> >>> But in cycle mode it outputs normal voltages.
> >>>
> >>> I suspect a wiring fault but I can't see any mistakes, unless of course I
> >> have misunderstood how to wire it up - which is likely!
> >>> Hoping its an easy fix and thanks in advance
> >>> - Kevin
> >>>
> >>
> >>
> >>
> >> ------------------------------------
> >>
> >> The CGS Modular Synth home page: http://www.cgs.synth.net/
> >> Yahoo! Groups Links
> >>
> >
>
>
>
> [Non-text portions of this message have been removed]
>