Cgs synth

From: "sasami@..." <sasami@...>
To: cgs_synth@yahoogroups.com
Sent: Saturday, August 3, 2013 9:44 PM
Subject: Re: [cgs_synth] CGS76 Serge 1973 Env Gen question

>Hi Ken and all
>
>I'm building up the OCB for the Serge 1973 Env Gen.
>
>There are three resistor i'm unclear on.
>
>33K# x 2 (Window size CV and Hold Input) , 22K# x 2 (Duration pot CW and

CCW) and the 2.2K and 1.8K in the 6V regulator section.

>I'm assuming the 22K's are there if you are using a 25K pot for Duration.

yes. Use 100k with 100k pot, 22k with 25k pot.

>Just need to know if the 2.2K and 1.8K in the 6V regulator section are

supposed to be put in or left out. I'm not installing in a Vintage Serge.

They are needed. They are marked so people know which resistors to change if
they wish to adjust the regulator for 15 volt use. It is mentioned in the
notes at the bottom. It isn't critical.

>The 33K's have me stumped.

Origianlly 33k on the Serge units. 100k would be more appropriate for modern
synths.

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




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From: Dmitri SFC <dankedout415@...>
To: cgs_synth@yahoogroups.com
Sent: Saturday, August 3, 2013 10:01 AM
Subject: [cgs_synth] Re: CGS76 Serge 1973 Env Gen question




I populate 73EG per the solder mask with all 100k pots & it works great.
d

--
<http://www.facebook.com/dmitri.sfc>

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[Non-text portions of this message have been removed]

> 33K# x 2 (Window size CV and Hold Input)

They are pull down resistors.

>22K# x 2 (Duration pot CW and CCW)

They are part of two voltage dividers that feed the + and - inputs of a summing amplifier (the LM3900). They must be there.

> Just need to know if the 2.2K and 1.8K in the 6V regulator section are supposed to be put in or left out. I'm not installing in a Vintage Serge.
>

Yes you need them to get 6V out of the 15V input. The 6V "regulator" is just a buffered voltage divider.

Best regards
Gaston