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CGS 87 outputs

CGS 87 outputs

2016-07-22 by phijel

Hello


I'm currently building a TPS and successfully completed the 16 steps sequencer part (including the vertical sequence with a CGS 28)


This panel is really amazing, much more powerful than the TKB as a pattern generator IMHO.


But I'm running it currently from +/- 15V, and I realized the outputs at their max are quite high (between 14-15 V) so I'm afraid it might be harmful for the Serge in some cases.


Would there be an easy way to address this ?


Would a simple voltage divider on the outputs do the trick or is there something else I might change to lower it ?


Thanks !

Re: CGS 87 outputs

2016-07-22 by Ken Stone

It shouldn't worry the Serge at all. Serge inputs (according to the Gold Book) can take up to 25V in, and I've seen nothing to contradict that. These voltages are turned into tiny currents by the input resistors. In the case of mixed inputs, the current from two 7.5 volt signals would be the equivalent to that of a 15V signal.
The worst that might happen would be an op-amp going into phase-inversion lock-up, and that can be solved by powering down and up again.
Show quoted textHide quoted text
On Fri, Jul 22, 2016 at 6:32 PM, philippe@... [cgs_synth] <cgs_synth@yahoogroups.com> wrote:

Hello


I'm currently building a TPS and successfully completed the 16 steps sequencer part (including the vertical sequence with a CGS 28)


This panel is really amazing, much more powerful than the TKB as a pattern generator IMHO.


But I'm running it currently from +/- 15V, and I realized the outputs at their max are quite high (between 14-15 V) so I'm afraid it might be harmful for the Serge in some cases.


Would there be an easy way to address this ?


Would a simple voltage divider on the outputs do the trick or is there something else I might change to lower it ?


Thanks !




--
Ken Stone otherunicorn@...
Modular Synth PCBs for sale <http://www.cgs.synth.net/>

Re: CGS 87 outputs

2016-07-22 by phijel

Thanks Ken, good to know (I remember blowing my DUSG zener by accidentally sending 15V to it, but it was probably into one output)


It was also to conform with the Serge "standards" of 0-5 V for the sequencers, but maybe it's not that important, and just a matter of habit.


So, not sure I'll do it, but just in case, would the voltage divider do the trick you think ? Any drawback to this ?


Thanks

Re: CGS 87 outputs

2016-07-22 by Ken Stone

Yes, that zener is on an output, and was a poorly thought-out modification. My version addresses that weakness by protecting the zener with a resistor.
Show quoted textHide quoted text
On Fri, Jul 22, 2016 at 7:38 PM, philippe@... [cgs_synth] <cgs_synth@yahoogroups.com> wrote:

Thanks Ken, good to know (I remember blowing my DUSG zener by accidentally sending 15V to it, but it was probably into one output)


It was also to conform with the Serge "standards" of 0-5 V for the sequencers, but maybe it's not that important, and just a matter of habit.


So, not sure I'll do it, but just in case, would the voltage divider do the trick you think ? Any drawback to this ?


Thanks




--
Ken Stone otherunicorn@...
Modular Synth PCBs for sale <http://www.cgs.synth.net/>

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