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CGS48 v1 ASM-1 Mod and the 47uF

CGS48 v1 ASM-1 Mod and the 47uF

2012-03-27 by Joachim

Hi,

oh no, it's me again. ;)

I have a question about the 'ASM-1 mod' that is mentioned for +/- 15 V operation:

First the mentioned 330K resistor seems to have gotten a 220K in V1.0.
According to the ASM-1 schematic the 240K would be replaced by a 560K and the now 220K by 200K.
But what about the 47uF capacitor? As this feeds into the waveshaper section it looks like
it cannot be simply omitted because it is 'redundant'. My guess is that I should put a link
there and omit the 100K from the second saw output to ground.

As I'm not sure if it's OK to include attachments in this list I have uploaded a picture with
the compiled changes here:
http://www.sdiy.de/pcb_cgs48_v1_vco_asm1_mod.png

Cheers
Joachim

CGS38: Do the 600K have to be 1/4W or is 1/8W sufficient?

2012-03-28 by Joachim

Hi,

as I didn't yet get an answer regarding the ASM-1 mod for the CGS48 I started
soldering my CGS38 instead. Then I stumbled across the 600K resistors
(btw. the two 100n 1206SMT are missing in the parts list):

Is 1/8W sufficient for these? Because then I could use Mouser no. 71-RN55D-F-600K for these.

(If I really need 600K for the ASM-1 mod of the CGS48, too, it would be interesting if I could
you them there also)

Cheers
Joachim

Re: CGS38: Do the 600K have to be 1/4W or is 1/8W sufficient?

2012-03-28 by Ove Ridé

On 28 March 2012 20:32, Joachim <sonicwarrior@...> wrote:
Show quoted textHide quoted text
> Hi,
>
> as I didn't yet get an answer regarding the ASM-1 mod for the CGS48 I started
> soldering my CGS38 instead. Then I stumbled across the 600K resistors
> (btw. the two 100n 1206SMT are missing in the parts list):
>
> Is 1/8W sufficient for these? Because then I could use Mouser no. 71-RN55D-F-600K for these.
>
> (If I really need 600K for the ASM-1 mod of the CGS48, too, it would be interesting if I could
> you them there also)

As a general rule of thumb, hardly any current will flow through these
high value resistors in a low voltage circuit like synth circuit. If
in doubt, imagine the worst case scenario where the resistor is
connected between the voltage rails. You can do this calculation
easily with Google:

(30 volts)^2/(600 kiloohms)

This ends up being 0.0015 watts, so about 10 times lower than the
rated wattage. Of course, under most circumstances, a resistor in a
circuit will be connected in a way that makes the current much lower
than this theoretical maximum.

--
/Ove

Blog: <http://blog.gg8.se/>

"Here is Evergreen City. Evergreen is the color of green forever."

Re: CGS38: Do the 600K have to be 1/4W or is 1/8W sufficient?

2012-03-28 by Joachim

OK, looks like that was a stupid question. Forgot about Ohm's law.
Thanks that you answered regardless of that.

Cheers
Joachim

Am 28.03.2012 21:22, schrieb Ove Ridé:
Show quoted textHide quoted text
> On 28 March 2012 20:32, Joachim<sonicwarrior@...> wrote:
>> Hi,
>>
>> as I didn't yet get an answer regarding the ASM-1 mod for the CGS48 I started
>> soldering my CGS38 instead. Then I stumbled across the 600K resistors
>> (btw. the two 100n 1206SMT are missing in the parts list):
>>
>> Is 1/8W sufficient for these? Because then I could use Mouser no. 71-RN55D-F-600K for these.
>>
>> (If I really need 600K for the ASM-1 mod of the CGS48, too, it would be interesting if I could
>> you them there also)
>
> As a general rule of thumb, hardly any current will flow through these
> high value resistors in a low voltage circuit like synth circuit. If
> in doubt, imagine the worst case scenario where the resistor is
> connected between the voltage rails. You can do this calculation
> easily with Google:
>
> (30 volts)^2/(600 kiloohms)
>
> This ends up being 0.0015 watts, so about 10 times lower than the
> rated wattage. Of course, under most circumstances, a resistor in a
> circuit will be connected in a way that makes the current much lower
> than this theoretical maximum.
>

Re: CGS38: Do the 600K have to be 1/4W or is 1/8W sufficient?

2012-03-28 by sasami@hotkey.net.au

>as I didn't yet get an answer regarding the ASM-1 mod for the CGS48 I started
>soldering my CGS38 instead.

I have never used the so-called ASM-1 mod myself.

>Then I stumbled across the 600K resistors
>Is 1/8W sufficient for these? Because then I could use Mouser no.
71-RN55D-F-600K for these.

Yes, they are sufficient. 1/8 W would be sufficient for all resistors of 10k
or higher in CGS circuits (except tube circuits).

Ken

_______________________________________________________________________
Ken Stone sasami@... otherunicorn@...
Modular Synth PCBs for sale <http://www.cgs.synth.net/>
Australian Miniature Horses & Ponies <http://www.blaze.net.au/~sasami/>

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