[sdiy] SG3821 Transistor array

[thx1138]

On 9/10/09 5:18 PM, "John Henson" <synthnerd at eircom.net> wrote:

> Hi Terry and list,
> I remember reading an interview with Dave Hemsath of Moog.
> I cannot recall whether it was the text file on Analogue Heaven or the book
> Analog Days, but the gist is that the Moog engineers looked at the LM3046 as
> Expo converters but didn't think they were good enough. A company called
> Silicon General (sic) gave them samples of the SG3821 which in Bill's words
> were very tightly matched, and the Mark 2 Minimoog Oscillator board was the
> result.
> I rebuilt a Mini with a serial number in the 1600's and it had the 2
> original SG3821's in it which is interesting as every other Mini I've worked
> on has had one of the 3046's replaced at some point.
> The newer 3046's are probably far better than the early 70's versions and
> should be a quite adequate substitute.
> Regards
> John
> ----- Original Message -----
> From: "thx1138" <thx1138 at earthlink.net>
> To: "SDIY List" <synth-diy at dropmix.xs4all.nl>
> Sent: Thursday, September 10, 2009 5:49 PM
> Subject: [sdiy] SG3821 Transistor array
> 
> 
>> Hi SDIY folks.
>> 
>> I am rebuilding the Universal Active Filter Module designed back in 1973.
>> 
>> I am looking for a Data Sheet on the SG3821 Transistor array.
>> 
>> It has been a long time singe I used this part and if anyone has a better
>> replacement suggestion I would be interested in your comments.
>> 
>> I was looking at the CA3046 and CA3086 devices and these type of parts.
>> 
>> We used them at Oberheim for the SEM1-A for Osc. 1 & 2 designs.
>> 
>> I just have not been able to get a data sheet on the SG3821. It would be
>> nice to keep the same part in the design but I am afraid it may be hard to
>> find these days.
>> 
>> Regards,
>> 
>> Terry
>> 
>> _______________________________________________
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>> Synth-diy at dropmix.xs4all.nl
>> http://dropmix.xs4all.nl/mailman/listinfo/synth-diy
>> 
>> 
> 
> 
Hi John,

My alternative is to use LM194/LM394 type of Matched transistors and I think
ADI has a matched Pair still available.

The other alternative is to match my own transistors but what a chore.

What is irritating me more than anything is the lack of good Analog discrete
suppliers these days. I feel like I am scrounging for parts and thwarted on
all fronts.

I guess it is time to look at bulk buys and hampstering away parts in my
garage for rainy day projects.

When I build stuff, I at least like to build up a batch to make it worth my
while.

Software guys just laugh at me at work. They think a DSP guy with my
background is nuts to go back to good ol' analog processing.

Software synths just don't have any soul like a good ol' Modular synth.

I don't even care if it is polyphonic with a 24 track ProTools system here
at the house to record multi-track.

Just some more Non-sequitor rambling

Regards,

Terry